Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

Oscar Vidal-Casanella; Oscar Núñez; Mercè Granados; Javier Saurina; Sonia Sentellas

doi:10.3390/app11188276

Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

Vidal-Casanella, Oscar;Núñez, Oscar;Granados, Mercè;Saurina, Javier;Sentellas, Sonia 2021-09-07 00:00:00 applied sciences Review Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols 1 1 , 2 1 1 , 2 , 1 , 3 Oscar Vidal-Casanella , Oscar Núñez , Mercè Granados , Javier Saurina * and Sonia Sentellas Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, 08028 Barcelona, Spain; oscarvidalcasanella@gmail.com (O.V.-C.); oscar.nunez@ub.edu (O.N.); mgranados@ub.edu (M.G.); sonia.sentellas@ub.edu (S.S.) Research Institute in Food Nutrition and Food Safety, Recinte Torribera, University of Barcelona, 08921 Santa Coloma de Gramenet, Spain Serra Húnter Lecturer, Generalitat de Catalunya, 08007 Barcelona, Spain * Correspondence: xavi.saurina@ub.edu Featured Application: The relevance of phenolic acids, ﬂavonoids, and other polyphenols as the biologically active components of nutraceuticals is pointed out here. The principal analytical approaches to deal with their characterization and quantiﬁcation have been introduced as well, with liquid chromatography being the technique of choice in most cases. Abstract: Phenolic compounds such as phenolic acids, ﬂavonoids, and stilbenes comprise an enor- mous family of bioactive molecules with a range of positive properties, including antioxidant, antimicrobial, or anti-inﬂammatory effects. As a result, plant extracts are often puriﬁed to recover phenolic compound-enriched fractions to be used to develop nutraceutical products or dietary sup- plements. In this article, we review the properties of some remarkable plant-based nutraceuticals in which the active molecules are mainly polyphenols and related compounds. Methods for the Citation: Vidal-Casanella, O.; Núñez, characterization of these extracts, the chemical determination of the bioactivities of key molecules, O.; Granados, M.; Saurina, J.; and the principal applications of the resulting products are discussed in detail. Sentellas, S. Analytical Methods for Exploring Nutraceuticals Based on Keywords: polyphenols; ﬂavonoids; bioactive compounds; antioxidants; nutraceuticals; analyti- Phenolic Acids and Polyphenols. cal methods Appl. Sci. 2021, 11, 8276. https:// doi.org/10.3390/app11188276 Academic Editor: Andrea Salvo 1. Introduction The consumption of nutraceutical products and functional foods has experienced Received: 20 July 2021 enormous growth in the last decade due to the crucial role to help prevent some diseases, Accepted: 31 August 2021 as well as the positive effects for human health associated with the bioactive compounds Published: 7 September 2021 that they contain [1–3]. Among the different groups of phytochemicals, polyphenols are especially remarkable for several reasons, namely: (i) they are responsible for some Publisher’s Note: MDPI stays neutral organoleptic attributes of natural products, such as color, astringency, or bitterness [4]; (ii) with regard to jurisdictional claims in they are important descriptors of features of plants and derived products to be used as published maps and institutional afﬁl- biomarkers for quality control, classiﬁcation, and authentication purposes [5]; (iii) there is iations. solid evidence that the consumption of phenolic compounds found in natural foods may lower the risk of suffering health disorders thanks to their antioxidant capacities [2,3,6]. The last point is the most important regarding this paper as it refers to the beneﬁcial and healing properties of this great family of molecules. Copyright: © 2021 by the authors. Polyphenols comprise a large family of secondary metabolites of plants that are Licensee MDPI, Basel, Switzerland. especially abundant in red berries, chocolate, tea, wine, and fresh fruits, displaying con- This article is an open access article centrations that may vary from milligrams to grams per kilogram depending on the cases. distributed under the terms and The regular intake of these foods constitutes the main source of polyphenols for the human conditions of the Creative Commons diet. However, given the great interest of polyphenols, their natural sources are often ex- Attribution (CC BY) license (https:// ploited to obtain enriched and/or puriﬁed extracts with potential applications to cosmetics, creativecommons.org/licenses/by/ nutraceuticals, food supplements, and medicines. 4.0/). Appl. Sci. 2021, 11, 8276. https://doi.org/10.3390/app11188276 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, x FOR PEER REVIEW 2 of 17 Appl. Sci. 2021, 11, 8276 2 of 16 exploited to obtain enriched and/or purified extracts with potential applications to cos- metics, nutraceuticals, food supplements, and medicines. In particular, polyphenols may protect the organism against oxidative damage, thus In particular, polyphenols may protect the organism against oxidative damage, thus limiting the risk of several degenerative diseases related to the harmful action of free limiting the risk of several degenerative diseases related to the harmful action of free rad- radicals such as cancer, diabetes, and osteoporosis [2,6]. Beyond this generic antioxidant icals such as cancer, diabetes, and osteoporosis [2,6]. Beyond this generic antioxidant ac- action, more speciﬁc antiviral, antimicrobial, or anti-inﬂammatory properties attributed to tion, more specific antiviral, antimicrobial, or anti-inflammatory properties attributed to given compounds have been reported as well [7–10]. Speciﬁc examples are given in the given compounds have been reported as well [7–10]. Specific examples are given in the following sections. following sections. 2. Polyphenols and Related Compounds 2. Polyphenols and Related Compounds They are primarily synthesized as signaling and defensive molecules against external They are primarily synthesized as signaling and defensive molecules against external stressors, such as climatic and environmental factors (drought, high temperature, solar stressors, such as climatic and environmental factors (drought, high temperature, solar radiation, and pollution) and pathogens, thus allowing plants to respond promptly to radiation, and pollution) and pathogens, thus allowing plants to respond promptly to multiple aggressions of different origins [11,12]. Strictly speaking, polyphenols consist of multiple aggressions of different origins [11,12]. Strictly speaking, polyphenols consist of organic compounds containing several phenolic groups. Other related compounds are organic compounds containing several phenolic groups. Other related compounds are sometimes included under this generic designation so that, in a broader context, the family sometimes included under this generic designation so that, in a broader context, the fam- of polyphenols and related compounds is as follows: phenolic acids, ﬂavonoids, stilbenes, ily of polyphenols and related compounds is as follows: phenolic acids, flavonoids, stil- lignans, as well as a more heterogeneous group of structurally related compounds such as benes, lignans, as well as a more heterogeneous group of structurally related compounds chalcones, humulones, and alcohols [12,13]. such as chalcones, humulones, and alcohols [12,13]. The number of polyphenol molecules that have been reported, identiﬁed, or character- The number of polyphenol molecules that have been reported, identified, or charac- ized is close to 9000. A brief explanation of the four main classes is given as follows (see terized is close to 9000. A brief explanation of the four main classes is given as follows (see Figure 1): Figure 1): Figure 1. Classiﬁcation of polyphenols according to their structures with some representative molecules of each family. Figure 1. Classification of polyphenols according to their structures with some representative molecules of each family. (i) Phenolic acids comprise hydroxybenzoic and hydroxycinnamic acids. They account (i) Phenolic acids comprise hydroxybenzoic and hydroxycinnamic acids. They account for 30% of the total dietary phenolics, and, in general, cinnamic derivatives, such as for 30% of the total dietary phenolics, and, in general, cinnamic derivatives, such as caffeic, ferulic, and coumaric acids, are more abundant than the benzoic ones. Tartaric caffeic, ferulic, and coumaric acids, are more abundant than the benzoic ones. Tar- esters of these acids (e.g., caftaric and coutaric acids) are especially abundant in grape, taric esters of these acids (e.g., caftaric and coutaric acids) are especially abundant in vine, and wines. In addition, quinic acid derivatives such as chlorogenic acids are present in a broad range of products (e.g., coffee, tea, and pear). Phenolic acids also include hydrolyzable tannins, which consist of sugar residues esteriﬁed with gallic or Appl. Sci. 2021, 11, 8276 3 of 16 ellagic acids. This type of tannin can be found at 10 to 100 mg kg levels in coffee, fruits, nuts, tea, and wine. (ii) Flavonoids are the largest family of polyphenols both qualitatively and quantitatively as more than 5000 different molecules have been described, accounting for 60% of the total dietary polyphenols in humans [14]. The ﬂavonoid backbone consists of two aromatic rings connected through a linking heterocycle with an oxygen and three carbon atoms (C6-C3-C6 skeleton). Flavonoids can be divided into six subclasses, namely: ﬂavonols, ﬂavones, isoﬂavones, ﬂavanones, anthocyanidins, and ﬂavanols. Additional details are given below. Flavonols are based on the hydroxyﬂavone backbone in which the phenyl residues can be variedly hydroxylated (or methoxylated), thus resulting in various remarkable aglycones such as quercetin, kaempferol, ﬁsetin, and morin [15–17]. In nature, they are predominantly linked to sugars as a way to enhance their solubility in intra- and extracellular media. Hence, glucosides, galactosides, rhamnosides, and rutinosides are frequently found in plant matrices. Although ﬂavonols are found at low concentrations, they play fundamental roles in growth regulation mechanisms. Flavones consist of the 2-phenylchromen-4-one backbone, structurally similar to ﬂavonols but without the hydroxyl group [18,19]. Some representative molecules are api- genin, luteolin, and tangeritin, generally occurring at levels below 1 mg kg in vegetables such a broccoli, celery, carrot, parsley, or spinach. C- and O-glycosides have been reported in cereals such as sorghum and millet at levels from 0.05 to 10 mg kg . Isoﬂavones are also based on the 2-phenylchromen-4-one backbone, differing from the ﬂavones in the position of the phenyl group. Isoﬂavones are almost speciﬁc to the Fabaceae family, occurring at concentrations of 1 mg kg in soybean, chickpea, peanut, and sunﬂower seeds [20,21]. Some typical aglycones are daidzin and genistin, often glycosided to a high extent. Despite their low concentrations in natural sources, they have great interest due to their structural resemblance with steroid hormones. Hence, isoﬂavones act as estrogens to alleviate postmenopausal effects (e.g., hot ﬂashes and bone loss) in women and to lower cholesterol levels in blood. Flavanones consist of ﬂavan-4-one structures without the double bond in the het- erocycle so that they have chiral carbons. As in the other cases, phenyl rings display varied hydroxylation (and methoxylation), with some representative aglycones being hesperetin, naringenin, taxifolin, and eriodictyol. They are predominantly combined with saccharides, resulting in compounds such as hesperidin, naringin, or narirutin. Fla- vanones are the main polyphenols in species of the Citrus genus, reaching concentrations of 100 to 3000 mg kg [22]. The main ﬂavanone bioactivities deal with the antioxidant and radical scavenging power, thus being used as prophylactics to reduce the risk of cancer and cardiovascular diseases. Anthocyanidin aglycones and anthocyanin glycosides are charged species containing the ﬂavylium cation (the oxygen of the heterocycle is an oxonium cation). The principal aglycones (e.g., cyanidin, delphinidin, malvidin, and pelargonidin) are often attached to sugars. They are the largest group of pigments found in nature responsible for the cyan and red colors of berries, grapes, tomatoes, and wine [23]. Flavanols, also referred to as ﬂavan-3-ols or catechins, are one of the most important families of polyphenols from both quantitative and qualitative issues [24–26]. Flavanols are present in high amounts in cocoa, coffee, fruits (berries, grapes, pears, and apples), legumes (peas, lentils, and beans), nuts (walnut, hazelnut, and peanut), and tea. For example, overall concentrations in fresh fruits are about 50 to 250 mg kg , reaching even 1 1 higher values in green tea (ca. 700 mg kg ) and cocoa (ca. 2000 mg kg ). As ﬂavanones, the heterocycle lacks the double bond so that they have chiral carbons. ()-Epicatechin and (+)-catechin, ()-epigallocatechin, ()-epicatechin gallate, and ()-epigallocatechin gallate are the most remarkable ﬂavanols. They are prone to condense to form the so- called proanthocyanidins (PACs) or condensed tannins, which consist of two or several ﬂavonoid moieties attached in different ways, thus resulting in dimers, trimers, and larger Appl. Sci. 2021, 11, 8276 4 of 16 oligomers [9,27]. Monomers are often connected via the C4 of the upper unit with the C6 or C8 of the lower counterpart (B-type bond). However, in speciﬁc cases, they have an additional link between the C2 of the upper monomer and the hydroxyl group of C5 or C7 of the lower one (i.e., C2-O-C5 or C2-O-C7), thus resulting in the so-called A-type bond. As detailed below, B-type compounds are more abundant in nature but the A-type ones possess a noticeable antimicrobial activity [28]. (iii) Stilbenes are characterized by a double-bond connecting two aromatic rings. Despite being found in low quantities in the human diet, the signiﬁcance of compounds such as trans-resveratrol is outstanding. Apart from the more controversial antiaging effects, chemopreventive, chemotherapeutic, cardioprotective, and neuroprotective beneﬁts have been attributed to resveratrol and its derivatives [29]. Curcuminoids are structurally related stilbenoids exhibiting a great range of nutritional and health beneﬁcial properties [30]. Their structure has been used as the basis to design new drugs for the treatment of several types of cancers and microbial infections [30]. (iv) Lignans are a minor class of polyphenols consisting of two phenylpropane units. The main food source of lignans is linseed, although they are also found at lower concentrations in cereals, fruits, and vegetables [31]. Recently, lignans have at- tracted the attention of researchers because of their potential anti-inﬂammatory, anti-neurodegenerative, antiviral, antimicrobial, and phytoestrogenic activities. 3. Nutraceuticals from Plant Extracts A type of trendy nutraceutical and dietary supplement consists of mixtures of fruit and medicinal plant extracts such as American cranberry and other red and blackberries, turmeric, grapevine, and green tea, with exceptional detoxifying, antiaging, and antioxidant features [32]. American cranberry (Vaccinium macrocarpon) is rich in a wide variety of phytochemi- cals such as saccharides, carotenoids, phenolic acids, and ﬂavonoids [33,34]. Fresh berries, raisins, and powdered extracts have been used as natural remedies to treat inﬂammatory and microbial processes. Other properties have also been recognized, including antineo- plastic, cardioprotective, or antidegenerative activities [35,36]. Regarding antimicrobial issues, A-type PACs are the main compounds to be used for the prophylaxis and treat- ment of urinary tract infections (UTIs). The bioactivity of these species is attributed to their planar structure, which may create a protecting barrier on the urinary tract walls, thus avoiding the adhesion of bacteria [9]. Cranberry extracts are sometimes combined with other medicinal plants such as Salvia ofﬁcinalis, Urtica urens, or Solidago virgaurea that provide additional anti-inﬂammatory and diuretic properties to facilitate the excretion of urine. Another group of nutraceuticals is focused on products to reduce weight and control obesity [37]. For this purpose, raspberry (Rubus idaeus) and green tea (Camellia sinensis) ex- tracts have been widely used, often combined in the same pharmaceutical form in slimming treatments [38,39]. Raspberry contains phenolic ketones (e.g., 4-phenylbutan-2-one) that activate the fat metabolism, while green tea is rich in caffeine and epigallocatechin with fat- burning properties. Adjuvant plant extracts with diuretic activity are sometimes included in the composition of this type of product to reinforce the feeling of weight reduction. Preparations based on grape (Vitis vinifera) extracts are highly rich in phenolic acids, ﬂavonoids, and stilbenes. Their high antioxidant power is undeniable, thus making grape extracts very healthy [40]. Grapevine is another product derived from Vitis vinifera rich in resveratrol and many other polyphenols, such as rutinosides, with cardioprotective and anti-inﬂammatory properties to be used in venous insufﬁciency [41]. Nutraceuticals made with artichoke (Cynara scolymus) possess hypolipidemic, detox, and hepatoprotective indications. Artichoke extracts contain high amounts of phenolic acids, sesquiterpenic lactones, and ﬂavonoids as the principal bioactive compounds [42,43]. Soya (Glycine max), as well as other members of Fabaceae, has been used traditionally in multiple nutraceutical products. The high content in polyphenols provides antioxidant, Appl. Sci. 2021, 11, 8276 5 of 16 antimicrobial, and hypolipidemic activity. However, its estrogenic property is probably the most remarkable attribute [20,21]. Hence, soya-based capsules containing puriﬁed extracts of isoﬂavones are widely used to treat menopausal symptoms. Turmeric (Curcuma longa) belongs to the ginger family, used for centuries as a remedy in traditional Asian pharmacy, as well as a valuable condiment in cuisine. Turmeric extracts or powders of dry rhizome are appreciated due to their antioxidant and anti- inﬂammatory activities. Turmeric is sometimes combined with other species such as ginger, garlic, and cinnamon for both nutraceutical and culinary purposes. Curcumin and related curcuminoids are the main bioactive compounds of turmeric [7]. Finally, a more diverse group of samples commercialized under detoxifying attributes has also been studied, consisting of mixtures of fruit extracts (Vaccinium corymbosum, Fragaria vesca, Vaccinium macrocarpom, Rubus idaeus, Ribes nigrum, Vaccinium myrtillus, Ruscus aculeatus, and Punica granatum) and some medicinal plants (e.g., Aesculus hippocastanum and Hamamelis virginiana). These preparations contain noticeable amounts of ﬂavanols (catechin, epicatechin, and procyanidin B2), as well as other phenolic acids and ﬂavonoids, providing great antioxidant, antimicrobial, anti-inﬂammatory effects [3]. 4. Analytical Methods for the Determination of Active Compounds in Nutraceutical Products In this section, an introduction to the principal approaches for the determination of active phenolic compounds in the nutraceutical samples is given. 4.1. Spectroscopic Methods 4.1.1. Antioxidant Indexes Colorimetric assays are broadly used to determine the antioxidant capacity (AC) in nutraceuticals, which is mainly related to the presence of phenolic compounds. Although there is some controversy about the reliability of AC values obtained by these in vitro chemical assays, they are simple and require cheap equipment, which makes them an attractive approach to estimate AC. Among the most used, we can highlight the assays of Folin–Ciocalteu, ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and 2,2 -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) [6]. The assays are based on a redox reaction (e.g., Folin–Ciocalteu and FRAP), some of them involving a radical reagent (e.g., DPPH and ABTS), which leads to a change in the UV-visible spectrum of the solution. In all of the methods, the calibration is performed with an individual compound (e.g., gallic acid and Trolox) and AC is expressed in terms of the equivalent concentration of the compound used for calibration. The Folin–Ciocalteu (FC) method is, probably, the most applied to determine the total phenolic content, and it is considered a proper assay to estimate AC in samples of plant origin. The method was initially developed for the analysis of proteins and was later extended to the analysis of polyphenols [44] based on a redox reaction involving the reduction of Mo (VI) to blue Mo (V) under alkaline conditions. The FRAP test is based on 3+ the reduction of the Fe (III)-2,2,6-tripyridyl-s-triazine (TPTZ) complex (Fe (TPZT) ) to the 2+ Fe (II)-TPTZ complex (Fe (TPZT) ), which has an intense blue color [45,46]. The FRAP assay is very simple and rugged, provided that the time elapsed between the start of the reaction and the measurements is kept under control. A large number of FRAP data of plant products can be found in the literature [47]. Other ligands (e.g., Fe (CN) ) have also been proposed to develop alternative colorimetric reactions. Regarding radical-based reactions, the DPPH assay is related to the scavenging activity of antioxidants against the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) [45]. DPPH is a stable radical, commercially available, and its solutions are violet in color, with an absorption maximum at 517 nm. The reduced form (DPPH-H) has a pale yellow color. Thus, when DPPH is reduced to DPPH-H by an antioxidant, the absorbance of the solution decreases. Although the method is widely applied to estimate AC, DPPH is not the best option for samples rich in anthocyanins, such as berries, cherries, and plums, because these Appl. Sci. 2021, 11, x FOR PEER REVIEW 6 of 17 Regarding radical-based reactions, the DPPH assay is related to the scavenging ac- tivity of antioxidants against the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) [45]. DPPH is a stable radical, commercially available, and its solutions are violet in color, with Appl. Sci. 2021, 11, 8276 6 of 16 an absorption maximum at 517 nm. The reduced form (DPPH-H) has a pale yellow color. Thus, when DPPH is reduced to DPPH-H by an antioxidant, the absorbance of the solu- tion decreases. Although the method is widely applied to estimate AC, DPPH is not the best option for samples rich in anthocyanins, such as berries, cherries, and plums, because compounds absorb in a similar range of wavelengths and interfere. The ABTS method is these compounds absorb in a similar range of wavelengths and inter + fere. The ABTS based on the scavenging activity of antioxidants against the ABTS radical cation, whose method is based on the scavenging activity of antioxidants against the ABTS radical cat- solutions have a dark blue color. ABTS is not commercially available and has to be ion, whose solutions have a dark b0lue color. ABTS is not commercially available and has generated by the oxidation of 2,2 -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) to be generated by the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) with peroxodisulfate [45]. A lot of AC data from ABTS assays for a wide variety of plant (ABTS) with peroxodisulfate [45]. A lot of AC data from ABTS assays for a wide variety samples have been reported [47]. of plant samples have been reported [47]. The comparison of results from different assays is not a trivial issue, as the sensitivity The comparison of results from different assays is not a trivial issue, as the sensitivity of each particular reducing species in each method is characteristic of the compound [48]. of each particular reducing species in each method is characteristic of the compound [48]. Figure 2, adapted from Reference [48] by Alcalde et al., compared various antioxidant Figure 2, adapted from Reference [48] by Alcalde et al., compared various antioxidant indexes for the series of hydroxybenzoic acids. Despite the structural similarity of these indexes for the series of hydroxybenzoic acids. Despite the structural similarity of these molecules, the antioxidant powers differed signiﬁcantly. The higher activities seemed to molecules, the antioxidant powers differed significantly. The higher activities seemed to be associated with the presence of more than one hydroxyl group conveniently oriented be associated with the presence of more than one hydroxyl group conveniently oriented in ortho or para positions, while those in meta or monohydroxylated species were less in ortho or para positions, while those in meta or monohydroxylated species were less ac- active. Hence, the strongest reducing agents according to the FC assay were dihydroxy- tive. Hence, the strongest reducing agents according to the FC assay were dihydroxy- and and trihydroxybenzoic acids with o- and p-conﬁgurations, while those not following this trihydroxybenzoic acids with o- and p-configurations, while those not following this pat- pattern were less efﬁcient. tern were less efficient. Figure 2. Figure 2.Comparison of anti Comparison of antioxidant oxidant indexe indexes s for the se for theriseries es of h of ydhydr roxyb oxybenzoic enzoic acids acids. . Data c Data orrecorr - e- spond to the normalized slopes of the calibration curves of each analyte and each method. Com- spond to the normalized slopes of the calibration curves of each analyte and each method. Com- pound assignation: 3-HBA, 3-hydroxybenzoic acid; 4-HBA, 4-hydroxybenzoic acid; 2,4-DHBA, 2,4- pound assignation: 3-HBA, 3-hydroxybenzoic acid; 4-HBA, 4-hydroxybenzoic acid; 2,4-DHBA, dihydroxybenzoic acid; 3,5-DHBA, 3,5-dihydroxybenzoic acid; 2,5-DHBA, 2,5-dihydroxybenzoic 2,4-dihydroxybenzoic acid; 3,5-DHBA, 3,5-dihydroxybenzoic acid; 2,5-DHBA, 2,5-dihydroxybenzoic acid; 2,3-DHBA, 2,3-dihydroxybenzoic acid; 3,4-DHBA, 3,4-dihydroxybenzoic acid; 2,4,6-THBA, acid; 2,3-DHBA, 2,3-dihydroxybenzoic acid; 3,4-DHBA, 3,4-dihydroxybenzoic acid; 2,4,6-THBA, 2,4,6- 2,4,6-trihydroxybenzoic acid; 2,3,4-THBA, 2,3,4-trihydroxybenzoic acid; gallic acid, 3,4,5-trihy- trihydroxybenzoic acid; 2,3,4-THBA, 2,3,4-trihydroxybenzoic acid; gallic acid, 3,4,5-trihydroxybenzoic droxybenzoic acid. Method assignation: FC, Folin–Ciocalteau; FRAP, ferric reducing antioxidant acid. Method assignation: FC, Folin–Ciocalteau; FRAP, ferric reducing antioxidant power; DPPH, power; DPPH, 2,-diphenyl-1-picrylhydrazyl; ABTS, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sul- fonic a 2,-diphenyl-1-picrylhydrazyl; cid)(adapted from reference [48]) ABTS, 2,2 . -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(adapted from reference [48]). In any case, it is recommended to apply several spectroscopic methods based on dif- ferent mech In any ancase, isms tit o achi is recommended eve complement toary apply inform several ation t spectr o evaloscopic uate the AC o methods f sample based s. on different mechanisms to achieve complementary information to evaluate the AC of samples. 4.1.2. Flavonoid Assays Apart from the indexes that provide information about the total AC, some assays focus on families of ﬂavonoids, such as the aluminum complexation assays, or the 4- dimethylaminocinnamaldehyde (DMAC) spectrophotometric method. For instance, ﬂavonols and ﬂavones form yellow complexes with Al(III) at neutral pH, and the absorbance of the solution is measured in the 400–430 nm range. Furthermore, Al(III) forms red complexes with some ﬂavonoids (e.g., rutin, luteolin, and catechins) in Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 17 4.1.2. Flavonoid Assays Apart from the indexes that provide information about the total AC, some assays focus on families of flavonoids, such as the aluminum complexation assays, or the 4-di- methylaminocinnamaldehyde (DMAC) spectrophotometric method. Appl. Sci. 2021, 11, 8276 7 of 16 For instance, flavonols and flavones form yellow complexes with Al(III) at neutral pH, and the absorbance of the solution is measured in the 400–430 nm range. Furthermore, Al(III) forms red complexes with some flavonoids (e.g., rutin, luteolin, and catechins) in the presence of sodium nitrite in an alkaline medium, and the absorbance of the solution is the presence of sodium nitrite in an alkaline medium, and the absorbance of the solution measured at 510 nm [49]. is measured at 510 nm [49]. Currently, DMAC is the most popular reagent for the quantiﬁcation of the overall PAC Currently, DMAC is the most popular reagent for the quantification of the overall content in nutraceuticals and functional foods. DMAC is an aromatic aldehyde that, under PAC content in nutraceuticals and functional foods. DMAC is an aromatic aldehyde that, strongly acidic conditions, reacts with ﬂavanols via the formation of a reactive electrophilic under strongly acidic conditions, reacts with flavanols via the formation of a reactive elec- carbocation. The DMAC reaction is speciﬁc to ﬂavanols and their gallates. DMAC reacts trophilic carbocation. The DMAC reaction is specific to flavanols and their gallates. with the C8 position of the terminal unit to form a green chromophore with maximum DMAC reacts with the C8 position of the terminal unit to form a green chromophore with absorbance at ca. 640 nm. Hence, interferences from the colored anthocyanidins can be maximum absorbance at ca. 640 nm. Hence, interferences from the colored anthocyanidins avoided [50–53]. PACs with a high degree of polymerization (DP) have lower responses can be avoided [50–53]. PACs with a high degree of polymerization (DP) have lower re- per unit weight than monomers and dimers [28,50,54]. sponses per unit weight than monomers and dimers [28,50,54]. 4.2. Voltammetric Methods 4.2. Voltammetric Methods Electroanalytical techniques such as cyclic voltammetry (CV) and differential pulse Electroanalytical techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) have been widely used for the detection of polyphenols. A direct voltammetry (DPV) have been widely used for the detection of polyphenols. A direct re- relationship between the concentration of electroactive functional groups and the current lationship between the concentration of electroactive functional groups and the current intensity generated is often found when they are either oxidized or reduced at the working intensity generated is often found when they are either oxidized or reduced at the work- electrode surface [55–57]. ing electrode surface [55–57]. The techniques commented above are especially recommended for the analysis of The techniques commented above are especially recommended for the analysis of polyphenols as their antioxidant properties are often related to the ability to donate elec- polyphenols as their antioxidant properties are often related to the ability to donate elec- trons. Voltammetric signals at low oxidation potentials suggest the presence of polypheno- trons. Voltammetric signals at low oxidation potentials suggest the presence of polyphe- lics of high antioxidant activity, whereas those compounds with low antioxidant power nolics of high antioxidant activity, whereas those compounds with low antioxidant power show electrochemical activity at more positive potentials [55,57]. Regarding electrodes, show electrochemical activity at more positive potentials [55,57]. Regarding electrodes, recent studies to determine polyphenols in nutraceuticals and related samples have re- recent studies to determine polyphenols in nutraceuticals and related samples have relied lied on a wide variety of working electrodes, such as the pencil-graphite electrode (PGE), on a wide variety of working electrodes, such as the pencil-graphite electrode (PGE), glassy carbon electrode (GCE), platinum (Pt), and different types of biosensors. In gen- glassy carbon electrode (GCE), platinum (Pt), and different types of biosensors. In general, eral, Pt has been used as an auxiliary electrode and Ag/AgCl (3 M KCl) as the reference Pt has been used as an auxiliary electrode and Ag/AgCl (3 M KCl) as the reference elec- electrode [55,57–59]. trode [55,57–59]. Some representative examples are depicted in Figure 3, which shows the differential Some representative examples are depicted in Figure 3, which shows the differential pulse voltammograms recorded in the range from0.2 to + 0.9 V vs. an Ag|AgCl|KCl ref- pulse voltammograms recorded in the range from −0.2 to + 0.9 V vs. an Ag|AgCl|KCl erence electrode. In the case of catechin, with two independent dihydroxyphenyl moieties, reference electrode. In the case of catechin, with two independent dihydroxyphenyl moi- two oxidation peaks corresponding to each side of the molecule have been detected. eties, two oxidation peaks corresponding to each side of the molecule have been detected. Figure 3. Differential pulse voltammograms recorded in the range from 0.2 to + 0.9 V vs. an Ag|AgCl|KCl reference Figure 3. Differential pulse voltammograms recorded in the range from −0.2 to + 0.9 V vs. an Ag|AgCl|KCl reference electrode for three representative examples: (a) 3,4-dihydroxybenzoic acid; (b) 2,4-dihydroxybenzoic acid; (c) catechin electrode for three representative examples: (a) 3,4-dihydroxybenzoic acid; (b) 2,4-dihydroxybenzoic acid; (c) catechin (adapted from reference [48]). (adapted from reference [48]). These techniques result in powerful alternatives to traditional spectrophotometric measurements due to the high sampling throughput, simplicity, sensitivity, reduced sample, and reagent consumption. However, one of the main issues of voltammetric studies is related to the electrode fouling during the measurements due to the adsorption of several nutraceutical sample components. In such circumstances, a cleaning step may be necessary before each voltammetric measurement to clean or renew the electrode surface [55,57,58,60]. Appl. Sci. 2021, 11, 8276 8 of 16 Some representative examples are mentioned as follows. For instance, grape extracts analyzed by CV with GCE showed a ﬁrst oxidation peak at 420 mV corresponding to the catechol group on the B-ring of ﬂavanols, and a second oxidation peak at 800–860 mV belonging to the resorcinol group on the A-ring [56]. In another study, the determination of TPC in Turkish green, black, and white tea extracts using DPV allowed a sensitive, rapid, and inexpensive evaluation of samples, with recoveries of caffeic acid around 95% [59]. In addition, DPV and CV were demonstrated to be appropriate to express the antioxidant activity of coffee extracts, presenting good correlations with DPPH spectrophotometric results [60]. 4.3. Chromatographic Methods Beyond the spectroscopic and voltammetric methods that provide information on the overall content of polyphenols, separation methods offer excellent opportunities for proﬁling. Thus, chromatographic techniques result in the best option for the simultaneous quantiﬁcation of several bioactive components occurring in the samples. Among the arsenal of techniques available in our current analytical laboratories, liquid chromatography seems to be the system of choice. Capillary electrophoresis (CE) can also be used owing to the ionizable nature of polyphenols. For instance, the phenolic content of herbal, fruit, or vegetable extracts has been determined using different CE modes such as capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), capillary isotachophoresis (CITP), and capillary electrochromatography (CEC) [61–65]. The polar and thermolabile nature of polyphenols hinders the use of gas chromatog- raphy (GC) for their direct determination. Hence, GC methods for the determination of polyphenols rely on derivatization procedures to reduce the polarity of analytes. In this regard, silylation has been successfully applied to the identiﬁcation and quantiﬁcation of phenolic compounds in plant and fruit extracts [66–69]. As mentioned, liquid chromatography (LC) is the best option for the determination of polyphenols in nutraceutical products and in plant extracts. In general, phenolic acids, stilbenes, and ﬂavonoids can be separated successfully by reversed-phase (RP) mode, typically with C18 or C8 columns. Beyond conventional High Performance LC (HPLC), the newest and most powerful instrumentation based on ultra-high-performance liquid chromatography (UHPLC) and core–shell column technology can be used. Mobile phases in LC are prepared with MeOH or ACN as organic solvents and acid aqueous solutions (e.g., using formic or acetic acids). The high complexity of the nutraceu- tical samples often requires customized elution gradients to achieve a good resolution of components. For instance, up to 15 polyphenols were determined in Taurisolo (grape pomace extract supplement, MBMed, Turin, Italy) using a polar RP-C18 HPLC column and an elution gradient generated with 0.1% formic acid in water (v/v) and acetonitrile [70]. López-Gutierrez et al. determined more than 30 polyphenol-related compounds in nu- traceutical samples (tablets and capsules) derived from green tea and grapes. The UHPLC separation was accomplished with sub-2 m particle-size C18 columns together with mass spectrometry (MS) detection [71,72]. To avoid expensive instrumental platforms, core–shell columns appeared as a good alternative to achieve excellent efﬁcacies. In this regard, Bakhytkyzy et al. used a Kinetex C18 reversed-phase (100 mm 4.6 mm ID, 2.6-m particle size) column for the determina- tion of ﬂavanols in dietary products and pharmaceuticals [73]. In another example, sub-2 m and porous-shell columns were compared for the determination of 29 polyphenols in cranberry-based pharmaceuticals obtaining, in that case, better performances using the UHPLC option [74]. As an alternative to the reverse-phase mode, the hydrophilic interaction chromatogra- phy (HILIC) has opened up great possibilities, especially for dealing with the most polar analytes that are weakly retained in RP columns. HILIC was used, for example, for the separation of ﬂavanols and related compounds in dietary supplements and nutraceuticals from berries, grapes, or artichoke extracts [75] (see Figure 4). The mobile phase consisted Appl. Sci. 2021, 11, x FOR PEER REVIEW 9 of 17 2 µm and porous-shell columns were compared for the determination of 29 polyphenols in cranberry-based pharmaceuticals obtaining, in that case, better performances using the UHPLC option [74]. As an alternative to the reverse-phase mode, the hydrophilic interaction chromatog- raphy (HILIC) has opened up great possibilities, especially for dealing with the most polar Appl. Sci. 2021, 11, 8276 9 of 16 analytes that are weakly retained in RP columns. HILIC was used, for example, for the separation of flavanols and related compounds in dietary supplements and nutraceuticals from berries, grapes, or artichoke extracts [75] (see Figure 4). The mobile phase consisted of acidified acetonitrile and methanol solutions, applying an elution gradient based on of acidiﬁed acetonitrile and methanol solutions, applying an elution gradient based on increasing the percentage of methanol. In this study, the authors highlighted the im- increasing the percentage of methanol. In this study, the authors highlighted the improved proved separation of flavanol oligomers, as well as the great potential to separate small separation of ﬂavanol oligomers, as well as the great potential to separate small phenolic phenolic acid molecules. acid molecules. Figure 4. Representative chromatograms of various nutraceutical samples obtained by HILIC-FLD. Figure 4. Representative chromatograms of various nutraceutical samples obtained by HILIC-FLD. Sample assignation: a = antioxidant extract; b = cranberry; c = cranberry (combined); d = artichoke; Sample assignation: a = antioxidant extract; b = cranberry; c = cranberry (combined); d = artichoke; e = red grape (peel and seeds); f = raspberry; g = grapevine. Compound assignation: 1 = catechin; 2 e = red grape (peel and seeds); f = raspberry; g = grapevine. Compound assignation: 1 = catechin; = epicatechin; 3 = procyanidin A2; 4 = procyanidin B2; 5 = trimer 1; 6 = procyanidin C1; 7 = tetramer 2 = epicatechin; 3 = procyanidin A2; 4 = procyanidin B2; 5 = trimer 1; 6 = procyanidin C1; 7 = tetramer 1; 8 = tetramer 2; 9 = pentamers; 10 = hexamers (adapted from reference [75]). 1; 8 = tetramer 2; 9 = pentamers; 10 = hexamers (adapted from reference [75]). The LC × LC strategy, combining different stationary phases, namely RP (or modified The LC LC strategy, combining different stationary phases, namely RP (or modiﬁed RP), HILIC, and, less commonly, size-exclusion chromatography (SEC), has shown to be RP), HILIC, and, less commonly, size-exclusion chromatography (SEC), has shown to promising for the determination of polyphenols in food products [76,77]. LC × LC, oper- be promising for the determination of polyphenols in food products [76,77]. LC LC, ating in the off-line or on-line modes, offers improved separations taking advantage of the operating in the off-line or on-line modes, offers improved separations taking advantage of orthogonality between the first and second dimensions. Consequently, sample clean-up the orthogonality between the ﬁrst and second dimensions. Consequently, sample clean-up procedures can be simplified by reducing the total analysis time. In this regard, an RP-LC procedures can be simpliﬁed by reducing the total analysis time. In this regard, an RP-LC × RP-LC method, combining a micro-bore ES-CN column (1D) with a C18 column (2D), RP-LC method, combining a micro-bore ES-CN column (1D) with a C18 column (2D), was successfully applied to the determination of 51 polyphenolic compounds in pistachio was successfully applied to the determination of 51 polyphenolic compounds in pistachio extracts [78]. Another study performed by Sommella et al. for the determination of poly- extracts [78]. Another study performed by Sommella et al. for the determination of polyphe- phenols in apple extracts samples combined HILIC × RP in the two-dimensional LC [79]. nols in apple extracts samples combined HILIC RP in the two-dimensional LC [79]. In In this case, higher peak capacities and sensitivities were obtained with the optimized this case, higher peak capacities and sensitivities were obtained with the optimized online online HILIC × RP-UHPLC-MS method concerning previously 1D reported methods. HILIC RP-UHPLC-MS method concerning previously 1D reported methods. Regarding detection, apart from the widespread UV-vis spectroscopy, fluorescence Regarding detection, apart from the widespread UV-vis spectroscopy, ﬂuorescence and mass spectrometry have been utilized to increase the sensitivity and selectivity of the and mass spectrometry have been utilized to increase the sensitivity and selectivity of the methods. In UV-Vis, current multi-way spectrophotometers such as diode-array detectors methods. In UV-Vis, current multi-way spectrophotometers such as diode-array detectors allow the simultaneous detection of the different phenolic families. For instance, the range allow the simultaneous detection of the different phenolic families. For instance, the 270–280 nm is used to monitor benzoic acids, flavanols, flavanones, and other species con- range 270–280 nm is used to monitor benzoic acids, ﬂavanols, ﬂavanones, and other taining phenyl moieties, 310–330 nm is used for hydroxycinnamic acids and stilbenes, species containing phenyl moieties, 310–330 nm is used for hydroxycinnamic acids and 370–380 nm is used for flavones, isoflavones, and flavonols, 420–430 nm is used for cur- stilbenes, 370–380 nm is used for ﬂavones, isoﬂavones, and ﬂavonols, 420–430 nm is used cuminoids, and 450–550 nm is used for anthocyanins. for curcuminoids, and 450–550 nm is used for anthocyanins. As most of the polyphenolic compounds have ﬂuorescent moieties in their structures, ﬂuorometric detection is an excellent alternative to the UV counterpart, thus providing enhanced performance from a proper selection of the excitation and emission wavelengths. For instance, ﬂavanols are detected at 280 nm and 320 nm with negligible in- ex em terferences from other phenolic families; 325 nm and 375 nm are good choices ex em for the determination of hydroxycinnamic acids; 375 nm and 430 nm have been ex em recommended for ﬂavonols, ﬂavones, and isoﬂavones. Currently, MS is the most powerful detector for qualitative and quantitative deter- minations of phenolic compounds. In our opinion, the hyphenation of MS with liquid chromatography deserves a more exhaustive development. Hence, the state of the art of application of HPLC-MS to polyphenol characterization is given below. Appl. Sci. 2021, 11, x FOR PEER REVIEW 10 of 17 As most of the polyphenolic compounds have fluorescent moieties in their structures, fluorometric detection is an excellent alternative to the UV counterpart, thus providing enhanced performance from a proper selection of the excitation and emission wave- lengths. For instance, flavanols are detected at λex 280 nm and λem 320 nm with negligible interferences from other phenolic families; λex 325 nm and λem 375 nm are good choices for the determination of hydroxycinnamic acids; λex 375 nm and λem 430 nm have been rec- ommended for flavonols, flavones, and isoflavones. Currently, MS is the most powerful detector for qualitative and quantitative deter- minations of phenolic compounds. In our opinion, the hyphenation of MS with liquid Appl. Sci. 2021, 11, 8276 10 of 16 chromatography deserves a more exhaustive development. Hence, the state of the art of application of HPLC-MS to polyphenol characterization is given below. Liquid Chromatography Coupled to Mass Spectrometry Liquid Chromatography Coupled to Mass Spectrometry HPLC-MS techniques, and more recently, the UHPLC-MS counterparts, have been HPLC-MS techniques, and more recently, the UHPLC-MS counterparts, have been increasingly used in nutraceutical characterization, especially for bioanalytical applica- increasingly used in nutraceutical characterization, especially for bioanalytical applica- tions dealing with pharmacokinetics and metabolism studies. LC-MS has been widely ex- tions dealing with pharmacokinetics and metabolism studies. LC-MS has been widely ploited for the identification and structural elucidation of known and unknown bioactive exploited for the identiﬁcation and structural elucidation of known and unknown bioactive molecules, especially from LC-MS/MS experiments [80,81]. Furthermore, high-resolution molecules, especially from LC-MS/MS experiments [80,81]. Furthermore, high-resolution mass spectrometers (HRMS) coupled to the LC systems result in exceptional tools for food mass spectrometers (HRMS) coupled to the LC systems result in exceptional tools for food analysis. Obtaining accurate mass measurements is the major advantage of HRMS to pro- analysis. Obtaining accurate mass measurements is the major advantage of HRMS to vide almost unambiguous identifications and quantifications. For instance, the presence provide almost unambiguous identiﬁcations and quantiﬁcations. For instance, the presence of curcumin and other curcuminoids in turmeric-based extracts was confirmed using this of curcumin and other curcuminoids in turmeric-based extracts was conﬁrmed using this strategy. As can be seen in Figure 5, the accurate mass spectra obtained by LC-HRMS with strategy. As can be seen in Figure 5, the accurate mass spectra obtained by LC-HRMS an orbitrap analyzer gave the authors reliable information for the identification of curcu- with an orbitrap analyzer gave the authors reliable information for the identiﬁcation of min and other major components in the studied samples [82]. curcumin and other major components in the studied samples [82]. Figure 5. Reversed-phase liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) total ion Figure 5. Reversed-phase liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) total ion chromatogram (a) and extracted ion chromatogram of curcumin (m/z 367.1187) (b). MS spectrum of peak at retention time chromatogram (a) and extracted ion chromatogram of curcumin (m/z 367.1187) (b). MS spectrum of peak at retention time of 13.52 min (c). Adapted from reference [82]. of 13.52 min (c). Adapted from reference [82]. By far, ESI is the most generalized ionization source, although atmospheric-pressure By far, ESI is the most generalized ionization source, although atmospheric-pressure chemical ionization (APCI) has also been proposed, especially for those compounds ex- chemical ionization (APCI) has also been proposed, especially for those compounds exhibit- hibiting low ionization efficiencies under ESI conditions [83–85]. This is the case, for in- ing low ionization efﬁciencies under ESI conditions [83–85]. This is the case, for instance, of stance, of the identification and determination of triterpenes and phenolic acids from an- the identiﬁcation and determination of triterpenes and phenolic acids from ancient apples cient apples of Friuli Venezia Giulia as nutraceutical ingredients [85]. While ESI resulted of Friuli Venezia Giulia as nutraceutical ingredients [85]. While ESI resulted in the best option in the best for opt the i determination on for the deteof rminat phenolic ion of phenol acids, APCI ic ac in ids, negative APCI in ion negat mode ive was ion mode wa selected as s selected as the ion source of terpenes due to the opportunity to obtain the pseudomolec- the ion source of terpenes due to the opportunity to obtain the pseudomolecular [M-H] ions ular [M with -H] higher ions wi intensity th higher i than ntensi with ty ESI than [86 wi ].th Car ESotenoids I [86]. Carotenoi are also ds a atypical re also family a typica of l compounds family of com exhibiting pounds exh better ibiting bet ionization ter iobehavior nization beh under avior unde APCI conditions r APCI condit in comparison ions in com- to parison to ESI [84,87,88]. For example, Garzón et al. [84] described the determination of ESI [84,87,88]. For example, Garzón et al. [84] described the determination of carotenoids fr ca om rotenoi Araz dá s from Araz (Eugenia stipitate á (Eug ),en an ia st Amazonian ipitate), an fr Ama uit with zonian potential fruit wi value th potenti as a a nutraceutical l value as a sour nutrace ce. u Recently tical source , UHPLC-APCI-T . Recently, UHP OF/MS LC-APCI-TOF/M was also proposed S was also for pr theoposed screening for th of e scre genistein en- fr ing o om fselected genisteiseeds n from se of Apiaceae lected see [d 89 s o ]. f Apiaceae [89]. T To dat o date, e, doz dozens ens of appl of applications ications of (U of (U)HPLC-ESI-MS(/MS) )HPLC-ESI-MS(/MS) h have ave bee been n publishe published. d. Low- Low- resolution mass spectrometers based on triple quadrupole and ion trap analyzers are resolution mass spectrometers based on triple quadrupole and ion trap analyzers are typ- typically ically propos proposed ed forfor the se the nsit sensitive ive de determination termination ofof well well-known -known bioact bioactive ive sub substances, stances, aas s well as for identiﬁcation purposes when working in tandem mass spectrometry [90–94]. For example, Nzekoue et al. carried out the quantiﬁcation of 30 bioactive compounds in coffee silverskin extracts by HPLC-MS/MS using a triple quadrupole analyzer [94]. Eighteen phenolic compounds were detected and quantiﬁed, with caffeoylquinic acids being the most abundant ones. In contrast, HPLC-DAD-MS using an ion-trap analyzer was employed to address a comprehensive characterization of the phytochemicals present in an Italian ancient apple “Mela Rosa dei Monti Sibillini” [93]. Extracts from lyophilized material were richer in polyphenolic compounds than the dried counterparts. These ﬁndings suggested that this ancient apple variety was an excellent source of active components for nutraceuticals. HRMS based on time-of-ﬂight (TOF) and Orbitrap analyzers is the technique of choice for a comprehensive characterization of plant-based extracts due to the higher-resolution Appl. Sci. 2021, 11, 8276 11 of 16 capabilities and the accurate mass measurements (with errors below 2 ppm depending on the instrument). In these cases, hybrid conﬁgurations combining quadrupole and ion-trap analyzers coupled with HRMS instruments such as Q-TOF [95–100], IT-TOF [101], and Q-Orbitrap [102,103] were preferred to take advantage of the high sensitivity of these platforms under full-scan acquisition mode. Furthermore, fragmentations can be employed for identiﬁcation purposes, especially when proﬁling strategies are applied. For instance, Amat-ur-Rasool et al. evaluated the potential nutraceutical properties of leaves from sev- eral commonly cultivated plants such as lemon (Citrus limon), red silk-cotton (Bombax ceiba), henna (Lawsonia inermis), eucalyptus (Eucalyptus globulus), basil (Ocimum basilicum), Mandarin orange (Citrus reticulata), and spearmint (Mentha spicata) [95]. RP HPLC cou- pled to a Q-TOF instrument working in negative ion electrospray mode was proposed as the instrumental technique. Several polyphenols such as 3-caffeoylquinic acid, methyl 4-caffeoylquinate, kaempferol-acetyl-glycoside, quercetin 3-rutinoside, quercetin-acetyl- glycoside, kaempferol 3-O-glucoside, and quercetin 3-O-glucoside were identiﬁed. In another work, a Q-Orbitrap HRMS instrument was used to assess a comprehensive investi- gation of the polyphenolic constituents of fennel waste extract, showing that chlorogenic acids were the most abundant compounds [102]. Some applications based on MS instru- ments with an even higher resolution than an Orbitrap analyzer, such as Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), have also been described in the literature. For example, Maia et al. [104] evaluated Vitis vinifera “Pinot noir” leaves as a source of bioactive nutraceutical compounds using an FT-ICR-MS instrument, identify- ing the presence of numerous compounds that are known to possess diverse nutritional and pharmacological properties, such as caffeic acid, catechin, kaempferol and quercetin, several phytosterols, and fatty acids. The use of ambient mass spectrometry (AMS) techniques has also been described for nutraceutical characterization. AMS involves the direct analysis of compounds from sample surfaces, allowing a straightforward study of unconventional bulk samples, such as whole tablets, plant parts, or tissue sections. The analysis takes place at ambient pressure outside the MS instrument, which speeds up the sampling process and without any sample preparation (or minimal sample manipulation). For example, Giffen et al. described the use of direct analysis in real time (DART) for the rapid identiﬁcation of Salvia species by chemometric processing [105]. The authors analyzed plant leaves in their native form by DART-HRMS without any sample preparation step, obtaining a derived chemical ﬁngerprinting of both fresh and dried salvia material. The presence of essential oil biomarkers such as 3-carene, -pinene, -pinene, -thujone, -caryophyllene, camphor, and borneol was conﬁrmed. In another work, Riya et al. revealed the important nutraceutical properties of Mauritius fruit (Ananas comosus) against diabetes [106]. In this case, some active compounds identiﬁed in ethyl acetate and methanolic extracts of the fruit using DART-HRMS were sinapic acid, daucosterol, 2-methylpropanoate, 2,3-dimethyl-4- hydroxy-4(2H)-furanone, methyl 2-methylbutanoate, and triterpenoid ergosterol. Desorption electrospray ionization (DESI) is another AMS technique allowing the direct identiﬁcation and determination of bioactive substances deposited on surfaces and from thin biological tissue sections with minimal (or without) sample treatment. In this case, a charged spray of solvent droplets is directed toward the surface to desorb and ionize the analytes, which are directed to the MS inlet under vacuum conditions. The investigation of phytochemicals from thin-layer chromatography (TLC) imprints or direct plant tissues is well described in the literature. As an example, the chemical proﬁling and separation of bioactive secondary metabolites in maca (Lepidium peruvianum) by normal- and reversed-phase TLC coupled to DESI-HRMS was proposed by Perez et al. [107]. The authors reported for the ﬁrst time the identiﬁcation of six potential plant antibiotics, phytoanticipins, glycosylated ascorbigens, and dihydroascorbigens from Maca seeds. Matrix-assisted laser desorption ionization (MALDI)TOF-MS is another excellent technique for the deeper characterization of polyphenols, especially for dealing with polymeric compounds such as PACs [108], especially for the elucidation of intermolecular Appl. Sci. 2021, 11, 8276 12 of 16 link positions. The polyphenol proﬁling of chestnut pericarp, integument, and curing water extracts to qualify these food by-products as a source of bioactive antioxidant compounds for nutraceutical applications was also described by MALDI-TOF-MS [109]. This method allowed the identiﬁcation of condensed and hydrolyzable tannins such as procyanidins and prodelphinidins. 5. Conclusions Polyphenols, including phenolic acids, ﬂavonoids, and stilbenes, display great an- tioxidant activity that may help to combat free radicals resulting from oxidative stress. Other interesting properties such as anti-inﬂammatory, antineoplastic, antimicrobial, hy- polipidemic, estrogenic, or hepatoprotective activities have been described as well. The chemical evaluation of these compounds is essential to ensure the content of the desired active species. Regarding analytical methods, spectroscopic methods are suitable for the evaluation of the overall antioxidant capacity of nutraceuticals. Electrochemical methods have also demonstrated their great performance to assess the antioxidant properties of products. The simultaneous proﬁling of multiple analytes relies on separation techniques, among which liquid chromatography is the most recommended one. Polyphenols can be monitored by UV/vis, ﬂuorescence, and mass spectrometry, with the latter being especially suitable for sensitive and selective detection. The hyphenation of liquid chromatography with mass spectrometry is also the technique of choice for the identiﬁcation and structural elucidation of unknown phytochemicals with bioactive properties. Author Contributions: J.S. conceived and designed the publication and wrote the core of the docu- ment; O.V.-C., O.N., M.G. and S.S. contributed to the bibliographic search, analysis of the information, and writing of different sections of the paper. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the “Agencia Estatal de Investigación”, grant number PID2020- 114401RB-C22. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Acknowledgments: Not applicable. Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. Leri, M.; Scuto, M.; Ontario, M.L.; Calabrese, V.; Calabrese, E.J.; Bucciantini, M.; Stefani, M. Healthy effects of plant polyphenols molecular mechanisms. Int. J. Mol. Sci. 2020, 21, 1250. [CrossRef] 2. Tomé-Carneiro, J.; Visioli, F. Polyphenol-based nutraceuticals for the prevention and treatment of cardiovascular disease: Review of human evidence. Phytomedicine 2016, 23, 1145–1174. [CrossRef] 3. Abuajah, C.I.; Ogbonna, A.C.; Osuji, C.M. Functional components and medicinal properties of food: A review. J. Food Sci. Technol. 2015, 52, 2522–2529. [CrossRef] 4. Lucci, P.; Saurina, J.; Núñez, O. Trends in LC-MS and LC-HRMS analysis and characterization of polyphenols in food. Trends Anal. Chem. 2017, 88, 1–24. [CrossRef] 5. Saurina, J. Characterization of wines using compositional proﬁles and chemometrics. Trends Anal. Chem. 2010, 29, 234–245. [CrossRef] 6. Gülçin, I. Antioxidant activity of food constituents: An overview. Arch. Toxicol. 2012, 86, 345–391. [CrossRef] [PubMed] 7. Farhood, B.; Mortezaee, K.; Goradel, N.H.; Khanlarkhani, N.; Salehi, E.; Nashtaei, M.S.; Najaﬁ, M.; Sahebkar, A. Curcumin as an anti-inﬂammatory agent: Implications to radiotherapy and chemotherapy. J. Cell. Physiol. 2019, 234, 5728–5740. [CrossRef] 8. Tabrizi, R.; Vakili, S.; Akbari, M.; Mirhosseini, N.; Lankarani, K.B.; Rahimi, M.; Mobini, M.; Jafarnejad, S.; Vahedpoor, Z.; Asemi, Z. The effects of curcumin-containing supplements on biomarkers of inﬂammation and oxidative stress: A systematic review and meta-analysis of randomized controlled trials. Phyther. Res. 2019, 33, 253–262. [CrossRef] 9. Tao, W.; Zhang, Y.; Shen, X.; Cao, Y.; Shi, J.; Ye, X.; Chen, S. Rethinking the Mechanism of the Health Beneﬁts of Proanthocyanidins: Absorption, Metabolism, and Interaction with Gut Microbiota. Compr. Rev. Food Sci. Food Saf. 2019, 18, 971–985. [CrossRef] Appl. Sci. 2021, 11, 8276 13 of 16 10. Coman, V.; Vodnar, D.C. Hydroxycinnamic acids and human health: Recent advances. J. Sci. Food Agric. 2020, 100, 483–499. [CrossRef] 11. Quideau, S.; Defﬁeux, D.; Douat-Casassus, C.; Pouységu, L. Plant polyphenols: Chemical properties, biological activities, and synthesis. Angew. Chemie Int. Ed. 2011, 50, 586–621. [CrossRef] 12. Tsao, R. Chemistry and biochemistry of dietary polyphenols. Nutrients 2010, 2, 1231–1246. [CrossRef] [PubMed] 13. Di Lorenzo, C.; Colombo, F.; Biella, S.; Stockley, C.; Restani, P. Polyphenols and human health: The role of bioavailability. Nutrients 2021, 13, 273. [CrossRef] 14. Panche, A.N.; Diwan, A.D.; Chandra, S.R. Flavonoids: An overview. J. Nutr. Sci. 2016, 5, e47. [CrossRef] 15. Flamini, R.; Mattivi, F.; De Rosso, M.; Arapitsas, P.; Bavaresco, L. Advanced knowledge of three important classes of grape phenolics: Anthocyanins, stilbenes and ﬂavonols. Int. J. Mol. Sci. 2013, 14, 19651–19669. [CrossRef] [PubMed] 16. Kubina, R.; Iriti, M.; Kabala-Dzik, A. Anticancer potential of selected ﬂavonols: Fisetin, kaempferol, and quercetin on head and neck cancers. Nutrients 2021, 13, 845. [CrossRef] [PubMed] 17. Ulusoy, H.G.; Sanlier, N. A minireview of quercetin: From its metabolism to possible mechanisms of its biological activities. Crit. Rev. Food Sci. Nutr. 2020, 60, 3290–3303. [CrossRef] [PubMed] 18. Hostetler, G.L.; Ralston, R.A.; Schwartz, S.J. Flavones: Food Sources, Bioavailability, Metabolism and Bioactivity. Adv. Nutr. 2017, 8, 423–435. [CrossRef] 19. Singh, M.; Kaur, M.; Silakari, O. Flavones: An important scaffold for medicinal chemistry. Eur. J. Med. Chem. 2014, 84, 206–239. [CrossRef] [PubMed] 20. Ko, K. Isoﬂavones: Chemistry, Analysis, Functions and Effects on Health and Cancer. Asian Pac. J. Cancer Prev. 2014, 15, 7001–7010. [CrossRef] 21. Messina, M. Soy foods, isoﬂavones, and the health of postmenopausal women. Am. J. Clin. Nutr. 2014, 100, 423S–430S. [CrossRef] 22. Testai, L.; Calderone, V. Nutraceutical value of citrus ﬂavanones and their implications in cardiovascular disease. Nutrients 2017, 9, 502. [CrossRef] 23. Tsuda, T. Dietary anthocyanin-rich plants: Biochemical basis and recent progress in health beneﬁts studies. Mol. Nutr. Food Res. 2012, 56, 159–170. [CrossRef] 24. Singh, B.N.; Shankar, S.; Srivastava, R.K. Green tea catechin, epigallocatechin-3-gallate (EGCG): Mechanisms, perspectives and clinical applications. Biochem. Pharmacol. 2011, 82, 1807–1821. [CrossRef] 25. Martin, M.A.; Ramos, S. Impact of dietary ﬂavanols on microbiota, immunity andinﬂammation in metabolic diseases. Nutrients 2021, 13, 850. [CrossRef] 26. Sabaghi, M.; Hoseyni, S.Z.; Tavasoli, S.; Mozafari, M.R.; Katouzian, I. Strategies of conﬁning green tea catechin compounds in nano-biopolymeric matrices: A review. Colloids Surfaces B Biointerfaces 2021, 204, 111781. [CrossRef] [PubMed] 27. Rauf, A.; Imran, M.; Abu-Izneid, T.; Patel, S.; Pan, X.; Naz, S.; Sanches Silva, A.; Saeed, F.; Rasul Suleria, H.A. Proanthocyanidins: A comprehensive review. Biomed. Pharmacother. 2019, 116, 108999. [CrossRef] 28. Krueger, C.G.; Reed, J.D.; Feliciano, R.P.; Howell, A.B. Quantifying and characterizing proanthocyanidins in cranberries in relation to urinary tract health. Anal. Bioanal. Chem. 2013, 405, 4385–4395. [CrossRef] [PubMed] 29. Mallebrera, B.; Maietti, A.; Tedeschi, P.; Font, G.; Ruiz, M.J.; Brandolini, V. Antioxidant capacity of trans-resveratrol dietary supplements alone or combined with the mycotoxin beauvericin. Food Chem. Toxicol. 2017, 105, 315–318. [CrossRef] 30. Kotha, R.R.; Luthria, D.L. Curcumin: Biological, pharmaceutical, nutraceutical, and analytical aspects. Molecules 2019, 24, 2930. [CrossRef] [PubMed] 31. Zálešák, F.; Bon, D.J.Y.D.; Pospíšil, J. Lignans and Neolignans: Plant secondary metabolites as a reservoir of biologically active substances. Pharmacol. Res. 2019, 146, 104284. [CrossRef] 32. Vidal-Casanella, O.; Nuñez, O.; Saurina, J. Liquid chromatographic ﬁngerprints for the characterization of ﬂavanol-rich nutraceu- ticals based on 4-dimethylaminocinnamaldehyde precolumn derivatization. Sci. Pharm. 2021, 89, 18. [CrossRef] 33. Gudzinskaite, I.; Stackeviciene, E.; Liaudanskas, M.; Zymone, K.; Zvikas, V.; Viskelis, J.; Urbstaite, R.; Janulis, V. Variability in the qualitative and quantitative composition and content of phenolic compounds in the fruit of introduced American cranberry (Vaccinium macrocarpon Aiton). Plants 2020, 9, 1379. [CrossRef] [PubMed] 34. Zhao, S.; Liu, H.; Gu, L. American cranberries and health beneﬁts—An evolving story of 25 years. J. Sci. Food Agric. 2020, 100, 5111–5116. [CrossRef] 35. Côté, J.; Caillet, S.; Doyon, G.; Sylvain, J.F.; Lacroix, M. Analyzing cranberry bioactive compounds. Crit. Rev. Food Sci. Nutr. 2010, 50, 872–888. [CrossRef] 36. Blumberg, J.B.; Camesano, T.A.; Cassidy, A.; Kris-Etherton, P.; Howell, A.; Manach, C.; Ostertag, L.M.; Sies, H.; Skulas-Ray, A.; Vita, J.A. Cranberries and their bioactive constituents in human health. Adv. Nutr. 2013, 4, 618–632. [CrossRef] 37. Wang, S.; Moustaid-Moussa, N.; Chen, L.; Mo, H.; Shastri, A.; Su, R.; Bapat, P.; Kwun, I.S.; Shen, C.L. Novel insights of dietary polyphenols and obesity. J. Nutr. Biochem. 2014, 25, 1–18. [CrossRef] [PubMed] 38. Ríos-Hoyo, A.; Gutiérrez-Salmeán, G. New Dietary Supplements for Obesity: What We Currently Know. Curr. Obes. Rep. 2016, 5, 262–270. [CrossRef] [PubMed] 39. Tsuda, T. Recent progress in anti-obesity and anti-diabetes effect of berries. Antioxidants 2016, 5, 13. [CrossRef] [PubMed] 40. Georgiev, V.; Ananga, A.; Tsolova, V. Recent advances and uses of grape ﬂavonoids as nutraceuticals. Nutrients 2014, 6, 391–415. [CrossRef] [PubMed] Appl. Sci. 2021, 11, 8276 14 of 16 41. Xia, E.Q.; Deng, G.F.; Guo, Y.J.; Li, H. Bin Biological activities of polyphenols from grapes. Int. J. Mol. Sci. 2010, 11, 622–646. [CrossRef] 42. Pereira, C.; Barros, L.; Ferreira, I.C. Extraction, identiﬁcation, fractionation and isolation of phenolic compounds in plants with hepatoprotective effects. J. Sci. Food Agric. 2016, 96, 1068–1084. [CrossRef] [PubMed] 43. Gostin, A.I.; Waisundara, V.Y. Edible ﬂowers as functional food: A review on artichoke (Cynara cardunculus L.). Trends Food Sci. Technol. 2019, 86, 381–391. [CrossRef] 44. Singleton, V.L.; Orthofer, R.; Lamuela-Raventós, R.M. Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent. Methods Enzymol. 1999, 299, 152–178. [CrossRef] 45. Gulcin, I. Antioxidants and antioxidant methods: An updated overview. Arch. Toxicol. 2020, 94, 651–715. [CrossRef] [PubMed] 46. Brainina, K.; Stozhko, N.; Vidrevich, M. Antioxidants: Terminology, methods, and future considerations. Antioxidants 2019, 8, 297. [CrossRef] [PubMed] 47. Shahidi, F.; Zhong, Y. Measurement of antioxidant activity. J. Funct. Foods 2015, 18, 757–781. [CrossRef] 48. Alcalde, B.; Granados, M.; Saurina, J. Exploring the Antioxidant Features of Polyphenols by Spectroscopic and Electrochemical Methods. Antioxidants 2019, 8, 523. [CrossRef] 49. Pekal, ˛ A.; Pyrzynska, K. Evaluation of Aluminium Complexation Reaction for Flavonoid Content Assay. Food Anal. Methods 2014, 7, 1776–1782. [CrossRef] 50. Feliciano, R.P.; Shea, M.P.; Shanmuganayagam, D.; Krueger, C.G.; Howell, A.B.; Reed, J.D. Comparison of isolated cran- berry (Vaccinium macrocarpon Ait.) proanthocyanidins to catechin and procyanidins A2 and B2 for use as standards in the 4-(dimethylamino)cinnamaldehyde assay. J. Agric. Food Chem. 2012, 60, 4578–4585. [CrossRef] 51. Payne, M.J.; Hurst, W.J.; Stuart, D.A.; Ou, B.; Fan, E.; Ji, H.; Kou, Y. Determination of total procyanidins in selected chocolate and confectionery products using DMAC. J. AOAC Int. 2010, 93, 89–96. [CrossRef] 52. Wang, Y.; Singh, A.P.; Hurst, W.J.; Glinski, J.A.; Koo, H.; Vorsa, N. Inﬂuence of Degree-of-Polymerization and Linkage on the Quantiﬁcation of Proanthocyanidins using 4-Dimethylaminocinnamaldehyde (DMAC) Assay. J. Agric. Food Chem. 2016, 64, 2190–2199. [CrossRef] [PubMed] 53. Vidal-Casanella, O.; Nuñez, O.; Hernández-Cassou, S.; Saurina, J. Assessment of Experimental Factors Affecting the Sensitivity and Selectivity of the Spectrophotometric Estimation of Proanthocyanidins in Foods and Nutraceuticals. Food Anal. Methods 2021, 14, 485–495. [CrossRef] 54. Krueger, C.G.; Chesmore, N.; Chen, X.; Parker, J.; Khoo, C.; Marais, J.P.J.; Shanmuganayagam, D.; Crump, P.; Reed, J.D. Critical reevaluation of the 4-(dimethylamino)cinnamaldehyde assay: Cranberry proanthocyanidin standard is superior to procyanidin A2 dimer for accurate quantiﬁcation of proanthocyanidins in cranberry products. J. Funct. Foods 2016, 22, 13–19. [CrossRef] 55. Arribas, A.S.; Martinez-Fernandez, M.; Chicharro, M. The role of electroanalytical techniques in analysis of polyphenols in wine. TrAC Trends Anal. Chem. 2012, 34, 78–96. [CrossRef] 56. Petrovic, S.C. Correlation of perceived wine astringency to cyclic voltammetric response. Am. J. Enol. Vitic. 2009, 60, 373–378. 57. Makhotkina, O.; Kilmartin, P.A. The use of cyclic voltammetry for wine analysis: Determination of polyphenols and free sulfur dioxide. Anal. Chim. Acta 2010, 668, 155–165. [CrossRef] 58. David, I.G.; Buleandră, M.; Popa, D.E.; Bîzgan, A.-M.C.; Moldovan, Z.; Badea, I.-A.; Iorgulescu, E.E.; Tekiner, T.A.; Basaga, H. Voltammetric determination of polyphenolic content as rosmarinic acid equivalent in tea samples using pencil graphite electrodes. J. Food Sci. Technol. 2016, 53, 2589–2596. [CrossRef] 59. David, I.G.; Bizgan, A.-M.C.; Popa, D.E.; Buleandra, M.; Moldovan, Z.; Badea, I.A.; Tekiner, T.A.; Basaga, H.; Ciucu, A.A. Rapid determination of total polyphenolic content in tea samples based on caffeic acid voltammetric behaviour on a disposable graphite electrode. Food Chem. 2015, 173, 1059–1065. [CrossRef] 60. Oliveira-Neto, J.R.; Rezende, S.G.; de Fátima Reis, C.; Benjamin, S.R.; Rocha, M.L.; de Souza Gil, E. Electrochemical behavior and determination of major phenolic antioxidants in selected coffee samples. Food Chem. 2016, 190, 506–512. [CrossRef] 61. Memon, A.F.; Solangi, A.R.; Memon, S.Q.; Mallah, A.; Memon, N. Quantitative separation of hesperidin, chrysin, epicatechin, epigallocatechin gallate, and morin using ionic liquid as a buffer additive in capillary electrophoresis. Electrophoresis 2018, 39, 1606–1612. [CrossRef] 62. Arries, W.J.; Tredoux, A.G.J.; de Beer, D.; Joubert, E.; de Villiers, A. Evaluation of capillary electrophoresis for the analysis of rooibos and honeybush tea phenolics. Electrophoresis 2017, 38, 897–905. [CrossRef] [PubMed] 63. Dresler, S.; Bogucka-Kocka, A.; Kovácik, ˇ J.; Kubrak, T.; Strzemski, M.; Wójciak-Kosior, M.; Rysiak, A.; Sowa, I. Separation and determination of coumarins including furanocoumarins using micellar electrokinetic capillary chromatography. Talanta 2018, 187, 120–124. [CrossRef] 64. Navarro, M.; Núñez, O.; Saurina, J.; Hernández-Cassou, S.; Puignou, L. Characterization of fruit products by capillary zone electrophoresis and liquid chromatography using the compositional proﬁles of polyphenols: Application to authentication of natural extracts. J. Agric. Food Chem. 2014, 62, 1038–1046. [CrossRef] [PubMed] 65. Przybylska, A.; Gackowski, M.; Koba, M. Application of capillary electrophoresis to the analysis of bioactive compounds in herbal raw materials. Molecules 2021, 26, 2135. [CrossRef] 66. Ahmad, N.; Zuo, Y.; Lu, X.; Anwar, F.; Hameed, S. Characterization of free and conjugated phenolic compounds in fruits of selected wild plants. Food Chem. 2016, 190, 80–89. [CrossRef] Appl. Sci. 2021, 11, 8276 15 of 16 67. Osman, M.F.; Hassan, N.M.; Khatib, A.; Tolos, S.M. Antioxidant activities of Dialium indum L. Fruit and gas chromatography-mass spectrometry (GC-MS) of the active fractions. Antioxidants 2018, 7, 154. [CrossRef] [PubMed] 68. Park, C.H.; Morgan, A.M.A.; Park, B.B.; Lee, S.Y.; Lee, S.; Kim, J.K.; Park, S.U. Metabolic analysis of four cultivars of liriope platyphylla. Metabolites 2019, 9, 59. [CrossRef] 69. Ifeanacho, M.O.; Ikewuchi, C.C.; Ikewuchi, J.C. Investigation of the proﬁle of phenolic compounds in the leaves and stems of Pandiaka heudelotii using gas chromatography coupled with ﬂame ionization detector. Food Sci. Nutr. 2017, 5, 646–652. [CrossRef] [PubMed] 70. Annunziata, G.; Maisto, M.; Schisano, C.; Ciampaglia, R.; Narciso, V.; Tenore, G.C.; Novellino, E. Effects of grape pomace polyphenolic extract (Taurisolo ) in reducing tmao serum levels in humans: Preliminary results from a randomized, placebo- controlled, cross-over study. Nutrients 2019, 11, 139. [CrossRef] [PubMed] 71. López-Gutiérrez, N.; Romero-González, R.; Plaza-Bolaños, P.; Martínez Vidal, J.L.; Garrido Frenich, A. Identiﬁcation and quantiﬁcation of phytochemicals in nutraceutical products from green tea by UHPLC-Orbitrap-MS. Food Chem. 2015, 173, 607–618. [CrossRef] 72. López-Gutiérrez, N.; Romero-González, R.; Martínez Vidal, J.L.; Frenich, A.G. Determination of polyphenols in grape-based nutraceutical products using high resolution mass spectrometry. LWT Food Sci. Technol. 2016, 71, 249–259. [CrossRef] 73. Bakhytkyzy, I.; Nuñez, O.; Saurina, J. Size Exclusion Coupled to Reversed Phase Liquid Chromatography for the Characterization of Cranberry Products. Food Anal. Methods 2019, 12, 604–611. [CrossRef] 74. Parets, L.; Alechaga, É.; Núñez, O.; Saurina, J.; Hernández-Cassou, S.; Puignou, L. Ultrahigh pressure liquid chromatography- atmospheric pressure photoionization-tandem mass spectrometry for the determination of polyphenolic proﬁles in the charac- terization and classiﬁcation of cranberry-based pharmaceutical preparations and natural ext. Anal. Methods 2016, 8, 4363–4378. [CrossRef] 75. Vidal-Casanella, O.; Arias-Alpizar, K.; Nuñez, O.; Saurina, J. Hydrophilic interaction liquid chromatography to characterize nutraceuticals and food supplements based on ﬂavanols and related compounds. Separations 2021, 8, 17. [CrossRef] 76. Cacciola, F.; Rigano, F.; Dugo, P.; Mondello, L. Comprehensive two-dimensional liquid chromatography as a powerful tool for the analysis of food and food products. TrAC Trends Anal. Chem. 2020, 127, 115894. [CrossRef] 77. Cacciola, F.; Arena, K.; Mandolﬁno, F.; Donnarumma, D.; Dugo, P.; Mondello, L. Reversed phase versus hydrophilic interaction liquid chromatography as ﬁrst dimension of comprehensive two-dimensional liquid chromatography systems for the elucidation of the polyphenolic content of food and natural products. J. Chromatogr. A 2021, 1645, 462129. [CrossRef] [PubMed] 78. Arena, K.; Cacciola, F.; Mangraviti, D.; Zoccali, M.; Rigano, F.; Marino, N.; Dugo, P.; Mondello, L. Determination of the polyphenolic fraction of Pistacia vera L. kernel extracts by comprehensive two-dimensional liquid chromatography coupled to mass spectrometry detection. Anal. Bioanal. Chem. 2019, 411, 4819–4829. [CrossRef] 79. Sommella, E.; Ismail, O.H.; Pagano, F.; Pepe, G.; Ostacolo, C.; Mazzoccanti, G.; Russo, M.; Novellino, E.; Gasparrini, F.; Campiglia, P. Development of an improved online comprehensive hydrophilic interaction chromatography reversed-phase ultra-high-pressure liquid chromatography platform for complex multiclass polyphenolic sample analysis. J. Sep. Sci. 2017, 40, 2188–2197. [CrossRef] 80. Tamasi, G.; Pardini, A.; Bonechi, C.; Donati, A.; Pessina, F.; Marcolongo, P.; Gamberucci, A.; Leone, G.; Consumi, M.; Magnani, A.; et al. Characterization of nutraceutical components in tomato pulp, skin and locular gel. Eur. Food Res. Tech- nol. 2019, 245, 907–918. [CrossRef] 81. Simeoni, M.C.; Pellegrini, M.; Sergi, M.; Pittia, P.; Ricci, A.; Compagnone, D. Analysis of Polyphenols in the Lamiaceae Family by Matrix Solid-Phase Dispersion Extraction Followed by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry Determination. ACS Omega 2018, 3, 17610–17616. [CrossRef] 82. Núñez, N.; Vidal-Casanella, O.; Sentellas, S.; Saurina, J.; Núñez, O. Characterization, classiﬁcation and authentication of turmeric and curry samples by targeted LC-HRMS polyphenolic and curcuminoid proﬁling and chemometrics. Molecules 2020, 25, 2942. [CrossRef] [PubMed] 83. Lozano-Mena, G.; Sánchez-González, M.; Parra, A.; Juan, M.E.; Planas, J.M. Identiﬁcation of gut-derived metabolites of maslinic acid, a bioactive compound from Olea europaea L. Mol. Nutr. Food Res. 2016, 60, 2053–2064. [CrossRef] 84. Garzón, G.A.; Narváez-Cuenca, C.E.; Kopec, R.E.; Barry, A.M.; Riedl, K.M.; Schwartz, S.J. Determination of carotenoids, total phenolic content, and antioxidant activity of Arazá (Eugenia stipitata McVaugh), an amazonian fruit. J. Agric. Food Chem. 2012, 60, 4709–4717. [CrossRef] [PubMed] 85. Sut, S.; Zengin, G.; Maggi, F.; Malagoli, M.; Dall’Acqua, S. Triterpene acid and phenolics from ancient apples of Friuli Venezia Giulia as nutraceutical ingredients: LC-MS study and in vitro activities. Molecules 2019, 24, 1109. [CrossRef] 86. Sut, S.; Poloniato, G.; Malagoli, M.; Dall’acqua, S. Fragmentation of the main triterpene acids of apple by LC- APCI-MSn. J. Mass Spectrom. 2018, 53, 882–892. [CrossRef] [PubMed] 87. Arrizabalaga-Larrañaga, A.; Campmajó, G.; Saurina, J.; Núñez, O.; Santos, F.J.; Moyano, E. Determination of capsaicinoids and carotenoids for the characterization and geographical origin authentication of paprika by UHPLC–APCI–HRMS. LWT- Food Sci. Technol. 2021, 139, 110533. [CrossRef] 88. Giuffrida, D.; Pintea, A.; Dugo, P.; Torre, G.; Pop, R.M.; Mondello, L. Determination of carotenoids and their esters in fruits of sea buckthorn (Hippophae rhamnoides L.) by HPLC-DAD-APCI-MS. Phytochem. Anal. 2012, 23, 267–273. [CrossRef] Appl. Sci. 2021, 11, 8276 16 of 16 89. Bettaiah, A.; Prabhushankar, H.B. Screening of Novel Source for Genistein by Rapid and Sensitive UPLC-APCI-TOF Mass Spectrometry. Int. J. Food Sci. 2021, 2021, 5537917. [CrossRef] 90. Zhou, Y.; Xu, X.Y.; Gan, R.Y.; Zheng, J.; Li, Y.; Zhang, J.J.; Xu, D.P.; Li, H. Bin Optimization of ultrasound-assisted extraction of antioxidant polyphenols from the seed coats of red sword bean (Canavalia gladiate (Jacq.) DC.). Antioxidants 2019, 8, 200. [CrossRef] 91. Sut, S.; Boschiero, I.; Solana, M.; Malagoli, M.; Bertucco, A.; Dall’Acqua, S. Supercritical CO extraction of eruca sativa using cosolvents: Phytochemical composition by LC-MS analysis. Molecules 2018, 23, 3240. [CrossRef] [PubMed] 92. El Majdoub, Y.O.; Alibrando, F.; Cacciola, F.; Arena, K.; Pagnotta, E.; Matteo, R.; Micalizzi, G.; Dugo, L.; Dugo, P.; Mondello, L. Chemical Characterization of Three Accessions of Brassica juncea L. Extracts from Different Plant Tissues. Molecules 2020, 25, 5421. [CrossRef] 93. Nkuimi Wandjou, J.G.; Lancioni, L.; Barbalace, M.C.; Hrelia, S.; Papa, F.; Sagratini, G.; Vittori, S.; Dall’Acqua, S.; Caprioli, G.; Beghelli, D.; et al. Comprehensive characterization of phytochemicals and biological activities of the Italian ancient apple ‘Mela Rosa dei Monti Sibillini. Food Res. Int. 2020, 137, 109422. [CrossRef] [PubMed] 94. Nzekoue, F.K.; Angeloni, S.; Navarini, L.; Angeloni, C.; Freschi, M.; Hrelia, S.; Vitali, L.A.; Sagratini, G.; Vittori, S.; Caprioli, G. Coffee silverskin extracts: Quantiﬁcation of 30 bioactive compounds by a new HPLC-MS/MS method and evaluation of their antioxidant and antibacterial activities. Food Res. Int. 2020, 133, 109128. [CrossRef] [PubMed] 95. Amat-Ur-rasool, H.; Symes, F.; Tooth, D.; Schaffert, L.N.; Elmorsy, E.; Ahmed, M.; Hasnain, S.; Carter, W.G. Potential nutraceutical properties of leaves from several commonly cultivated plants. Biomolecules 2020, 10, 1556. [CrossRef] 96. Reddy, M.N.; Adnan, M.; Alreshidi, M.M.; Saeed, M.; Patel, M. Evaluation of Anticancer, Antibacterial and Antioxidant Properties of a Medicinally Treasured Fern Tectaria coadunata with its Phytoconstituents Analysis by HR-LCMS. Anticancer. Agents Med. Chem. 2020, 20, 1845–1856. [CrossRef] 97. Rocchetti, G.; Senizza, B.; Zengin, G.; Mahomodally, M.F.; Senkardes, I.; Lobine, D.; Lucini, L. Untargeted metabolomic proﬁling of three Crataegus species (hawthorn) and their in vitro biological activities. J. Sci. Food Agric. 2020, 100, 1998–2006. [CrossRef] [PubMed] 98. Arshad, A.; Ahemad, S.; Saleem, H.; Saleem, M.; Zengin, G.; Abdallah, H.H.; Tousif, M.I.; Ahemad, N.; Mahomoodally, M.F. RP-UHPLC-MS chemical proﬁling, biological and in silico docking studies to unravel the therapeutic potential of heliotropium crispum desf. As a novel source of neuroprotective bioactive compounds. Biomolecules 2021, 11, 53. [CrossRef] 99. Rouphael, Y.; Bernardi, J.; Cardarelli, M.; Bernardo, L.; Kane, D.; Colla, G.; Lucini, L. Phenolic Compounds and Sesquiterpene Lactones Proﬁle in Leaves of Nineteen Artichoke Cultivars. J. Agric. Food Chem. 2016, 64, 8540–8548. [CrossRef] 100. Lachowicz, S.; Oszmianski, ´ J. Proﬁle of Bioactive Compounds in the Morphological Parts of Wild Fallopia japonica (Houtt) and Fallopia sachalinensis (F. Schmidt) and Their Antioxidative Activity. Molecules 2019, 24, 1436. [CrossRef] 101. Pepe, G.; Salviati, E.; Rapa, S.F.; Ostacolo, C.; Cascioferro, S.; Manfra, M.; Autore, G.; Marzocco, S.; Campiglia, P. Citrus sinensis and vitis vinifera protect cardiomyocytes from doxorubicin-induced oxidative stress: Evaluation of onconutraceutical potential of vegetable smoothies. Antioxidants 2020, 9, 378. [CrossRef] [PubMed] 102. Castaldo, L.; Izzo, L.; De Pascale, S.; Narváez, A.; Rodriguez-Carrasco, Y.; Ritieni, A. Chemical composition, in vitro bioacces- sibility and antioxidant activity of polyphenolic compounds from nutraceutical fennel waste extract. Molecules 2021, 26, 1968. [CrossRef] [PubMed] 103. Song, L.; Zheng, J.; Zhang, L.; Yan, S.; Huang, W.; He, J. Phytochemical Proﬁling and Fingerprint Analysis of Chinese Jujube (Ziziphus jujuba Mill.) Leaves of 66 Cultivars from Xinjiang Province. Molecules 2019, 24, 4528. [CrossRef] [PubMed] 104. Maia, M.; Ferreira, A.E.N.; Laureano, G.; Marques, A.P.; Torres, V.M.; Silva, A.B.; Matos, A.R.; Cordeiro, C.; Figueiredo, A.; Silva, M.S. Vitis vinifera “Pinot noir” leaves as a source of bioactive nutraceutical compounds. Food Funct. 2019, 10, 3822–3827. [CrossRef] [PubMed] 105. Giffen, J.E.; Lesiak, A.D.; Dane, A.J.; Cody, R.B.; Musah, R.A. Rapid Species-level Identiﬁcation of Salvias by Chemometric Processing of Ambient Ionisation Mass Spectrometry-derived Chemical Proﬁles. Phytochem. Anal. 2017, 28, 16–26. [CrossRef] [PubMed] 106. Riya, M.P.; Antu, K.A.; Vinu, T.; Chandrakanth, K.C.; Anilkumar, K.S.; Raghu, K.G. An in vitro study reveals nutraceutical properties of Ananas comosus (L.) Merr. var. Mauritius fruit residue beneﬁcial to diabetes. J. Sci. Food Agric. 2014, 94, 943–950. [CrossRef] 107. Perez, C.J.; Conceição, R.S.; Ifa, D.R. Chemical proﬁling and separation of bioactive secondary metabolites in Maca (Lepidium peruvianum) by normal and reverse phase thin layer chromatography coupled to desorption electrospray ionization-mass spectrometry. J. Mass Spectrom. 2021, 56, 1–14. [CrossRef] 108. Monagas, M.; Quintanilla-López, J.E.; Gómez-Cordovés, C.; Bartolomé, B.; Lebrón-Aguilar, R. MALDI-TOF MS analysis of plant proanthocyanidins. J. Pharm. Biomed. Anal. 2010, 51, 358–372. [CrossRef] 109. Pinto, G.; De Pascale, S.; Aponte, M.; Scaloni, A.; Addeo, F.; Caira, S. Polyphenol proﬁling of chestnut pericarp, integument and curing water extracts to qualify these food by-products as a source of antioxidants. Molecules 2021, 26, 2335. [CrossRef] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Applied Sciences Multidisciplinary Digital Publishing Institute http://www.deepdyve.com/lp/multidisciplinary-digital-publishing-institute/analytical-methods-for-exploring-nutraceuticals-based-on-phenolic-mXQDpn17jY

Loading next page...

References (109)

B. Mallebrera, A. Maietti, P. Tedeschi, G. Font, M. Ruiz, V. Brandolini (2017)
Antioxidant capacity of trans-resveratrol dietary supplements alone or combined with the mycotoxin beauvericin.
Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association, 105
Yifei Wang, Ajay Singh, W. Hurst, J. Gliński, H. Koo, N. Vorsa (2016)
Influence of Degree-of-Polymerization and Linkage on the Quantification of Proanthocyanidins using 4-Dimethylaminocinnamaldehyde (DMAC) Assay.
Journal of agricultural and food chemistry, 64 11
S. Quideau, D. Deffieux, Céline Douat-Casassus, L. Pouységu (2011)
Plant polyphenols: chemical properties, biological activities, and synthesis.
Angewandte Chemie, 50 3
Meritxell Navarro, O. Núñez, J. Saurina, S. Hernández‐Cassou, L. Puignou (2014)
Characterization of fruit products by capillary zone electrophoresis and liquid chromatography using the compositional profiles of polyphenols: application to authentication of natural extracts.
Journal of agricultural and food chemistry, 62 5
Oscar Vidal-Casanella, K. Arias-Alpízar, O. Núñez, J. Saurina (2021)
Hydrophilic Interaction Liquid Chromatography to Characterize Nutraceuticals and Food Supplements Based on Flavanols and Related Compounds
Separations, 8
C. Krueger, J. Reed, R. Feliciano, A. Howell (2013)
Quantifying and characterizing proanthocyanidins in cranberries in relation to urinary tract health
Analytical and Bioanalytical Chemistry, 405
S. Sut, G. Zengin, F. Maggi, M. Malagoli, S. Dall'acqua (2019)
Triterpene Acid and Phenolics from Ancient Apples of Friuli Venezia Giulia as Nutraceutical Ingredients: LC-MS Study and In Vitro Activities
Molecules, 24
Muhamad Osman, N. Hassan, A. Khatib, S. Tolos (2018)
Antioxidant Activities of Dialium indum L. Fruit and Gas Chromatography-Mass Spectrometry (GC-MS) of the Active Fractions
Antioxidants, 7
A. Memon, A. Solangi, S. Memon, A. Mallah, Najma Memon (2018)
Quantitative separation of hesperidin, chrysin, epicatechin, epigallocatechin gallate, and morin using ionic liquid as a buffer additive in capillary electrophoresis
ELECTROPHORESIS, 39
R. Tabrizi, S. Vakili, M. Akbari, N. Mirhosseini, K. Lankarani, M. Rahimi, M. Mobini, S. Jafarnejad, Z. Vahedpoor, Z. Asemi (2018)
The effects of curcumin‐containing supplements on biomarkers of inflammation and oxidative stress: A systematic review and meta‐analysis of randomized controlled trials
Phytotherapy Research, 33
F. Cacciola, Francesca Rigano, P. Dugo, L. Mondello (2020)
Comprehensive two-dimensional liquid chromatography as a powerful tool for the analysis of food and food products
TrAC Trends in Analytical Chemistry
A. Gostin, V. Waisundara (2019)
Edible flowers as functional food: A review on artichoke (Cynara cardunculus L.)
Trends in Food Science & Technology
C. Perez, Rodrigo Conceição, D. Ifa (2020)
Chemical profiling and separation of bioactive secondary metabolites in Maca (Lepidium peruvianum) by normal and reverse phase thin layer chromatography coupled to desorption electrospray ionization-mass spectrometry.
Journal of mass spectrometry : JMS, 56 2
Oscar Vidal-Casanella, O. Núñez, S. Hernández‐Cassou, J. Saurina (2020)
Assessment of Experimental Factors Affecting the Sensitivity and Selectivity of the Spectrophotometric Estimation of Proanthocyanidins in Foods and Nutraceuticals
Food Analytical Methods, 14
Nerea Núñez, Oscar Vidal-Casanella, S. Sentellas, J. Saurina, O. Núñez (2020)
Characterization, Classification and Authentication of Turmeric and Curry Samples by Targeted LC-HRMS Polyphenolic and Curcuminoid Profiling and Chemometrics
Molecules, 25
Chiara Lorenzo, F. Colombo, S. Biella, C. Stockley, P. Restani (2021)
Polyphenols and Human Health: The Role of Bioavailability
Nutrients, 13
H. Ulusoy, N. Sanli̇er (2020)
A minireview of quercetin: from its metabolism to possible mechanisms of its biological activities
Critical Reviews in Food Science and Nutrition, 60
Raghavendhar Kotha, Devanand Luthria (2019)
Curcumin: Biological, Pharmaceutical, Nutraceutical, and Analytical Aspects
Molecules, 24
V. Singleton, R. Orthofer, R. Lamuela-Raventós (1999)
Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteu reagent
Methods in Enzymology, 299
G. Annunziata, M. Maisto, Connie Schisano, R. Ciampaglia, Viviana Narciso, G. Tenore, E. Novellino (2019)
Effects of Grape Pomace Polyphenolic Extract (Taurisolo®) in Reducing TMAO Serum Levels in Humans: Preliminary Results from a Randomized, Placebo-Controlled, Cross-Over Study
Nutrients, 11
R. Flamini, F. Mattivi, M. Rosso, P. Arapitsas, L. Bavaresco (2013)
Advanced Knowledge of Three Important Classes of Grape Phenolics: Anthocyanins, Stilbenes and Flavonols
International Journal of Molecular Sciences, 14
Y. Rouphael, J. Bernardi, M. Cardarelli, L. Bernardo, D. Kane, G. Colla, L. Lucini (2016)
Phenolic Compounds and Sesquiterpene Lactones Profile in Leaves of Nineteen Artichoke Cultivars.
Journal of agricultural and food chemistry, 64 45
C. Krueger, Nathan Chesmore, Xin Chen, J. Parker, C. Khoo, J. Marais, D. Shanmuganayagam, Peter Crump, Jess Reed (2016)
Critical reevaluation of the 4-(dimethylamino)cinnamaldehyde assay: Cranberry proanthocyanidin standard is superior to procyanidin A2 dimer for accurate quantification of proanthocyanidins in cranberry products
Journal of Functional Foods, 22
I. Gülçin (2012)
Antioxidant activity of food constituents: an overview
Archives of Toxicology, 86
Noelia López-Gutiérrez, R. Romero-González, J. Vidal, A. Frenich (2016)
Determination of polyphenols in grape-based nutraceutical products using high resolution mass spectrometry
Lwt - Food Science and Technology, 71
Hafsa Amat-Ur-Rasool, Fenella Symes, D. Tooth, Larissa-Nele Schaffert, E. Elmorsy, Mehboob Ahmed, S. Hasnain, W. Carter (2020)
Potential Nutraceutical Properties of Leaves from Several Commonly Cultivated Plants
Biomolecules, 10
J. Côté, S. Caillet, Gilles Doyon, J.-F. Sylvain, Monique Lacroix (2010)
Analyzing Cranberry Bioactive Compounds
Critical Reviews in Food Science and Nutrition, 50
N. Ahmad, Y. Zuo, Xiaofei Lu, F. Anwar, S. Hameed (2016)
Characterization of free and conjugated phenolic compounds in fruits of selected wild plants.
Food chemistry, 190
Shaomin Zhao, Haiyan Liu, L. Gu (2020)
American cranberries and health benefits - an evolving story of 25 years.
Journal of the science of food and agriculture
G. Pinto, Sabrina Pascale, M. Aponte, A. Scaloni, F. Addeo, S. Caira (2021)
Polyphenol Profiling of Chestnut Pericarp, Integument and Curing Water Extracts to Qualify These Food By-Products as a Source of Antioxidants
Molecules, 26
S. Dresler, A. Bogucka-Kocka, J. Kováčik, Tomasz Kubrak, M. Strzemski, M. Wójciak-Kosior, A. Rysiak, I. Sowa (2018)
Separation and determination of coumarins including furanocoumarins using micellar electrokinetic capillary chromatography.
Talanta, 187
F. Shahidi, Y. Zhong (2015)
Measurement of antioxidant activity
Journal of Functional Foods, 18
A. Ríos-Hoyo, G. Gutiérrez-Salmeán (2016)
New Dietary Supplements for Obesity: What We Currently Know
Current Obesity Reports, 5
A. Panche, A. Diwan, Sheela Chandra (2016)
Flavonoids: an overview
Journal of Nutritional Science, 5
S. Sut, I. Boschiero, M. Solana, M. Malagoli, A. Bertucco, S. Dall'acqua (2018)
Supercritical CO2 Extraction of Eruca sativa Using Cosolvents: Phytochemical Composition by LC-MS Analysis
Molecules, 23
Brahma Singh, S. Shankar, R. Srivastava (2011)
Green tea catechin, epigallocatechin-3-gallate (EGCG): mechanisms, perspectives and clinical applications.
Biochemical pharmacology, 82 12
G. Tamasi, Alessio Pardini, C. Bonechi, A. Donati, F. Pessina, P. Marcolongo, A. Gamberucci, Gemma Leone, M. Consumi, A. Magnani, C. Rossi (2019)
Characterization of nutraceutical components in tomato pulp, skin and locular gel
European Food Research and Technology, 245
Shu Wang, N. Moustaid‐Moussa, Lixia Chen, H. Mo, Anuradha Shastri, Rui Su, Priyanka Bapat, I. Kwun, Chwan-Li Shen (2014)
Novel insights of dietary polyphenols and obesity.
The Journal of nutritional biochemistry, 25 1
C. Park, Abubaker Morgan, B. Park, Sook‐Young Lee, Sanghyun Lee, J. Kim, S. Park (2019)
Metabolic Analysis of Four Cultivars of Liriope platyphylla
Metabolites, 9
Kwang-Pil Ko (2014)
Isoflavones: chemistry, analysis, functions and effects on health and cancer.
Asian Pacific journal of cancer prevention : APJCP, 15 17
D. Giuffrida, A. Pintea, P. Dugo, Germana Torre, R. Pop, L. Mondello (2012)
Determination of carotenoids and their esters in fruits of sea buckthorn (Hippophae rhamnoides L.) by HPLC-DAD-APCI-MS.
Phytochemical analysis : PCA, 23 3
G. Garzón, C. Narváez‐Cuenca, R. Kopec, A. Barry, K. Riedl, S. Schwartz (2012)
Determination of carotenoids, total phenolic content, and antioxidant activity of Arazá (Eugenia stipitata McVaugh), an Amazonian fruit.
Journal of agricultural and food chemistry, 60 18
Noelia López-Gutiérrez, R. Romero-González, P. Plaza-Bolaños, J. Vidal, A. Frenich (2015)
Identification and quantification of phytochemicals in nutraceutical products from green tea by UHPLC-Orbitrap-MS.
Food chemistry, 173
Aparna Bettaiah, Hema Prabhushankar (2021)
Screening of Novel Source for Genistein by Rapid and Sensitive UPLC-APCI-TOF Mass Spectrometry
International Journal of Food Science, 2021
Maria Simeoni, M. Pellegrini, M. Sergi, P. Pittia, A. Ricci, D. Compagnone (2018)
Analysis of Polyphenols in the Lamiaceae Family by Matrix Solid-Phase Dispersion Extraction Followed by Ultra-High-Performance Liquid Chromatography–Tandem Mass Spectrometry Determination
ACS Omega
A. Pękal, K. Pyrzyńska (2014)
Evaluation of Aluminium Complexation Reaction for Flavonoid Content Assay
Food Analytical Methods, 7
Yue Zhou, Xiao-Yu Xu, R. Gan, Jie Zheng, Ya Li, Jiao-Jiao Zhang, Dong-ping Xu, Huabin Li (2019)
Optimization of Ultrasound-Assisted Extraction of Antioxidant Polyphenols from the Seed Coats of Red Sword Bean (Canavalia gladiate (Jacq.) DC.)
Antioxidants, 8
F. Nzekoue, Simone Angeloni, L. Navarini, C. Angeloni, Michela Freschi, S. Hrelia, L. Vitali, G. Sagratini, S. Vittori, G. Caprioli (2020)
Coffee silverskin extracts: Quantification of 30 bioactive compounds by a new HPLC-MS/MS method and evaluation of their antioxidant and antibacterial activities.
Food research international, 133
Lijun Song, Jie Zheng, Li Zhang, Shijuan Yan, Wenjie Huang, Jun He, Pengzhan Liu (2019)
Phytochemical Profiling and Fingerprint Analysis of Chinese Jujube (Ziziphus jujuba Mill.) Leaves of 66 Cultivars from Xinjiang Province
Molecules, 24
J. Wandjou, Laura Lancioni, M. Barbalace, S. Hrelia, F. Papa, G. Sagratini, S. Vittori, S. Dall'acqua, G. Caprioli, Daniella Beghelli, C. Angeloni, G. Lupidi, F. Maggi (2020)
Comprehensive characterization of phytochemicals and biological activities of the Italian ancient apple 'Mela Rosa dei Monti Sibillini'.
Food research international, 137
A. Arrizabalaga-Larrañaga, Guillem Campmajó, J. Saurina, O. Núñez, F. Santos, E. Moyano (2020)
Determination of capsaicinoids and carotenoids for the characterization and geographical origin authentication of paprika by UHPLC–APCI–HRMS
Lwt - Food Science and Technology
Berta Alcalde, M. Granados, J. Saurina (2019)
Exploring the Antioxidant Features of Polyphenols by Spectroscopic and Electrochemical Methods
Antioxidants, 8
G. Pepe, E. Salviati, S. Rapa, C. Ostacolo, S. Cascioferro, M. Manfra, G. Autore, S. Marzocco, P. Campiglia (2020)
Citrus sinensis and Vitis vinifera Protect Cardiomyocytes from Doxorubicin-Induced Oxidative Stress: Evaluation of Onconutraceutical Potential of Vegetable Smoothies
Antioxidants, 9
C. Abuajah, A. Ogbonna, C. Osuji (2015)
Functional components and medicinal properties of food: a review
Journal of Food Science and Technology, 52
K. Brainina, N. Stozhko, M. Vidrevich (2019)
Antioxidants: Terminology, Methods, and Future Considerations
Antioxidants, 8
A. Rauf, M. Imran, Tareq Abu-Izneid, Iahtisham-Ul-Haq, Seema Patel, Xian-dao Pan, S. Naz, A. Silva, F. Saeed, Hafiz Suleria (2019)
Proanthocyanidins: A comprehensive review.
Biomedicine & pharmacotherapy = Biomedecine & pharmacotherapie, 116
V. Coman, D. Vodnar (2020)
Hydroxycinnamic acids and human health. Recent advances.
Journal of the science of food and agriculture
T. Tsuda (2012)
Dietary anthocyanin-rich plants: biochemical basis and recent progress in health benefits studies.
Molecular nutrition & food research, 56 1
E. Sommella, Omar Ismail, Francesco Pagano, G. Pepe, C. Ostacolo, Giulia Mazzoccanti, M. Russo, E. Novellino, F. Gasparrini, P. Campiglia (2017)
Development of an improved online comprehensive hydrophilic interaction chromatography × reversed-phase ultra-high-pressure liquid chromatography platform for complex multiclass polyphenolic sample analysis.
Journal of separation science, 40 10
Yassine Majdoub, Filippo Alibrando, F. Cacciola, Katia Arena, E. Pagnotta, R. Matteo, G. Micalizzi, L. Dugo, P. Dugo, L. Mondello (2020)
Chemical Characterization of Three Accessions of Brassica juncea L. Extracts from Different Plant Tissues
Molecules, 25
Robert Kubina, M. Iriti, A. Kabała-Dzik (2021)
Anticancer Potential of Selected Flavonols: Fisetin, Kaempferol, and Quercetin on Head and Neck Cancers
Nutrients, 13
T. Tsuda (2016)
Recent Progress in Anti-Obesity and Anti-Diabetes Effect of Berries
Antioxidants, 5
Lidia Parets, Élida Alechaga, O. Núñez, J. Saurina, S. Hernández‐Cassou, L. Puignou (2016)
Ultrahigh pressure liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry for the determination of polyphenolic profiles in the characterization and classification of cranberry-based pharmaceutical preparations and natural extracts
Analytical Methods, 8
M. Monagas, J. Quintanilla-López, C. Gómez-Cordovés, B. Bartolomé, R. Lebrón-Aguilar (2010)
MALDI-TOF MS analysis of plant proanthocyanidins.
Journal of pharmaceutical and biomedical analysis, 51 2
M. Payne, W. Hurst, D. Stuart, B. Ou, Ellen Fan, Hongping Ji, Y. Kou (2010)
Determination of total procyanidins in selected chocolate and confectionery products using DMAC.
Journal of AOAC International, 93 1
I. Gulcin (2020)
Antioxidants and antioxidant methods: an updated overview
Archives of Toxicology, 94
S. Sut, G. Poloniato, M. Malagoli, S. Dall'acqua (2018)
Fragmentation of the main triterpene acids of apple by LC-APCI-MSn.
Journal of mass spectrometry : JMS, 53 9
I. David, M. Buleandră, D. Popa, Ana-Maria Bîzgan, Z. Moldovan, I. Badea, E. Iorgulescu, T. Tekiner, H. Basaga (2016)
Voltammetric determination of polyphenolic content as rosmarinic acid equivalent in tea samples using pencil graphite electrodes
Journal of Food Science and Technology, 53
V. Georgiev, Anthony Ananga, V. Tsolova (2014)
Recent Advances and Uses of Grape Flavonoids as Nutraceuticals
Nutrients, 6
F. Cacciola, Katia Arena, Filippo Mandolfino, Danilo Donnarumma, P. Dugo, L. Mondello (2021)
Reversed phase versus hydrophilic interaction liquid chromatography as first dimension of comprehensive two-dimensional liquid chromatography systems for the elucidation of the polyphenolic content of food and natural products.
Journal of chromatography. A, 1645
M. Martín, S. Ramos (2021)
Impact of Dietary Flavanols on Microbiota, Immunity and Inflammation in Metabolic Diseases
Nutrients, 13
František Zálešák, D. Bon, J. Pospíšil (2019)
Lignans and Neolignans: Plant secondary metabolites as a reservoir of biologically active substances.
Pharmacological research, 146
Moslem Sabaghi, Seyedeh Hoseyni, Sedighe Tavasoli, M. Mozafari, Iman Katouzian (2021)
Strategies of confining green tea catechin compounds in nano-biopolymeric matrices: A review.
Colloids and surfaces. B, Biointerfaces, 204
Gregory Hostetler, R. Ralston, S. Schwartz (2017)
Flavones: Food Sources, Bioavailability, Metabolism, and Bioactivity.
Advances in nutrition, 8 3
R. Tsao (2010)
Chemistry and Biochemistry of Dietary Polyphenols
Nutrients, 2
Oscar Vidal-Casanella, O. Núñez, J. Saurina (2021)
Liquid Chromatographic Fingerprints for the Characterization of Flavanol-Rich Nutraceuticals Based on 4-Dimethylaminocinnamaldehyde Precolumn Derivatization
Scientia Pharmaceutica, 89
Bagher Farhood, K. Mortezaee, N. Goradel, N. Khanlarkhani, E. Salehi, M. Nashtaei, M. Najafi, A. Sahebkar (2018)
Curcumin as an anti‐inflammatory agent: Implications to radiotherapy and chemotherapy
Journal of Cellular Physiology, 234
J. Blumberg, T. Camesano, A. Cassidy, P. Kris-Etherton, A. Howell, C. Manach, L. Ostertag, H. Sies, Ann Skulas-Ray, J. Vita (2013)
Cranberries and Their Bioactive Constituents in Human Health12
Advances in Nutrition, 4
Paolo Lucci, J. Saurina, O. Núñez (2017)
Trends in LC-MS and LC-HRMS analysis and characterization of polyphenols in food
Trends in Analytical Chemistry, 88
L. Testai, V. Calderone (2017)
Nutraceutical Value of Citrus Flavanones and Their Implications in Cardiovascular Disease
Nutrients, 9
S. Petrovic (2009)
Correlation of Perceived Wine Astringency to Cyclic Voltammetric Response
American Journal of Enology and Viticulture
A. Arshad, Saeed Ahemad, Hammad Saleem, M. Saleem, G. Zengin, H. Abdallah, M. Tousif, N. Ahemad, M. Mahomoodally (2021)
RP-UHPLC-MS Chemical Profiling, Biological and In Silico Docking Studies to Unravel the Therapeutic Potential of Heliotropium crispum Desf. as a Novel Source of Neuroprotective Bioactive Compounds
Biomolecules, 11
William Arries, A. Tredoux, D. Beer, E. Joubert, A. Villiers (2017)
Evaluation of capillary electrophoresis for the analysis of rooibos and honeybush tea phenolics
ELECTROPHORESIS, 38
João Tomé-Carneiro, F. Visioli (2016)
Polyphenol-based nutraceuticals for the prevention and treatment of cardiovascular disease: Review of human evidence.
Phytomedicine : international journal of phytotherapy and phytopharmacology, 23 11
Luigi Castaldo, L. Izzo, S. Pascale, A. Narváez, Y. Rodríguez-Carrasco, A. Ritieni (2021)
Chemical Composition, In Vitro Bioaccessibility and Antioxidant Activity of Polyphenolic Compounds from Nutraceutical Fennel Waste Extract
Molecules, 26
M. Ifeanacho, C. Ikewuchi, J. Ikewuchi (2016)
Investigation of the profile of phenolic compounds in the leaves and stems of Pandiaka heudelotii using gas chromatography coupled with flame ionization detector
Food Science & Nutrition, 5
I. Bakhytkyzy, O. Núñez, J. Saurina (2018)
Size Exclusion Coupled to Reversed Phase Liquid Chromatography for the Characterization of Cranberry Products
Food Analytical Methods, 12
G. Rocchetti, Biancamaria Senizza, G. Zengin, Mohamad Mahomodally, Ismail Senkardes, D. Lobine, L. Lucini (2019)
Untargeted metabolomic profiling of three Crataegus species (Hawthorn) and their in vitro biological activities.
Journal of the science of food and agriculture
A. Przybylska, Marcin Gackowski, M. Koba (2021)
Application of Capillary Electrophoresis to the Analysis of Bioactive Compounds in Herbal Raw Materials
Molecules, 26
E. Xia, G. Deng, Ya-Jun Guo, Huabin Li (2010)
Biological Activities of Polyphenols from Grapes
International Journal of Molecular Sciences, 11
Carla Pereira, L. Barros, I. Ferreira (2016)
Extraction, identification, fractionation and isolation of phenolic compounds in plants with hepatoprotective effects.
Journal of the science of food and agriculture, 96 4
S. Lachowicz, J. Oszmiański (2019)
Profile of Bioactive Compounds in the Morphological Parts of Wild Fallopia japonica (Houtt) and Fallopia sachalinensis (F. Schmidt) and Their Antioxidative Activity
Molecules, 24
A. Arribas, Marta Martínez-Fernández, M. Chicharro (2012)
The role of electroanalytical techniques in analysis of polyphenols in wine
Trends in Analytical Chemistry, 34
Katia Arena, F. Cacciola, Domenica Mangraviti, Mariosimone Zoccali, Francesca Rigano, Nino Marino, P. Dugo, L. Mondello (2019)
Determination of the polyphenolic fraction of Pistacia vera L. kernel extracts by comprehensive two-dimensional liquid chromatography coupled to mass spectrometry detection
Analytical and Bioanalytical Chemistry, 411
Ieva Gudžinskaitė, E. Stackevičienė, M. Liaudanskas, Kristina Zymonė, V. Žvikas, J. Viškelis, R. Urbštaitė, V. Janulis (2020)
Variability in the Qualitative and Quantitative Composition and Content of Phenolic Compounds in the Fruit of Introduced American Cranberry (Vaccinium macrocarpon Aiton)
Plants, 9
M. Riya, K. Antu, Thankamony Vinu, Karuvakandy Chandrakanth, K. Anilkumar, K. Raghu (2014)
An in vitro study reveals nutraceutical properties of Ananas comosus (L.) Merr. var. Mauritius fruit residue beneficial to diabetes.
Journal of the science of food and agriculture, 94 5
M. Leri, M. Scuto, M. Ontario, V. Calabrese, E. Calabrese, M. Bucciantini, M. Stefani (2020)
Healthy Effects of Plant Polyphenols: Molecular Mechanisms
International Journal of Molecular Sciences, 21
J. Oliveira-Neto, Stefani Rezende, Carolina Reis, Stephen Benjamin, M. Rocha, Eric Gil (2016)
Electrochemical behavior and determination of major phenolic antioxidants in selected coffee samples.
Food chemistry, 190
J. Saurina (2010)
Characterization of wines using compositional profiles and chemometrics
Trends in Analytical Chemistry, 29
Olga Makhotkina, P. Kilmartin (2010)
The use of cyclic voltammetry for wine analysis: determination of polyphenols and free sulfur dioxide.
Analytica chimica acta, 668 2
M. Maia, A. Ferreira, Gonçalo Laureano, A. Marques, Vukosava Torres, A. Silva, A. Matos, C. Cordeiro, A. Figueiredo, M. Silva (2019)
Vitis vinifera 'Pinot noir' leaves as a source of bioactive nutraceutical compounds.
Food & function
M. Messina (2014)
Soy foods, isoflavones, and the health of postmenopausal women.
The American journal of clinical nutrition, 100 Suppl 1
Manjinder Singh, Maninder Kaur, O. Silakari (2014)
Flavones: an important scaffold for medicinal chemistry.
European journal of medicinal chemistry, 84
I. David, Ana-Maria Bîzgan, D. Popa, M. Buleandră, Z. Moldovan, I. Badea, T. Tekiner, H. Basaga, A. Ciucu (2015)
Rapid determination of total polyphenolic content in tea samples based on caffeic acid voltammetric behaviour on a disposable graphite electrode.
Food chemistry, 173
R. Feliciano, Michael Shea, D. Shanmuganayagam, C. Krueger, A. Howell, J. Reed (2012)
Comparison of isolated cranberry (Vaccinium macrocarpon Ait.) proanthocyanidins to catechin and procyanidins A2 and B2 for use as standards in the 4-(dimethylamino)cinnamaldehyde assay.
Journal of agricultural and food chemistry, 60 18
Wenyang Tao, Yu Zhang, Xuemin Shen, Yanping Cao, John Shi, Xingqian Ye, Shiguo Chen (2019)
Rethinking the Mechanism of the Health Benefits of Proanthocyanidins: Absorption, Metabolism, and Interaction with Gut Microbiota.
Comprehensive reviews in food science and food safety, 18 4
G. Lozano-Mena, Marta Sánchez-González, A. Parra, M. Juan, J. Planas (2016)
Identification of gut-derived metabolites of maslinic acid, a bioactive compound from Olea europaea L.
Molecular nutrition & food research, 60 9
M. Reddy, M. Adnan, Mousa Alreshidi, Mohd Saeed, Mitesh Patel (2020)
Evaluation of Anticancer, Antibacterial and Antioxidant Properties of a Medicinally Treasured Fern Tectaria coadunata with its Phytoconstituents Analysis by HR-LCMS.
Anti-cancer agents in medicinal chemistry
Justine Giffen, A. Lesiak, A. Dane, R. Cody, R. Musah (2017)
Rapid Species-level Identification of Salvias by Chemometric Processing of Ambient Ionisation Mass Spectrometry-derived Chemical Profiles.
Phytochemical analysis : PCA, 28 1

Publisher: Multidisciplinary Digital Publishing Institute
Copyright: © 1996-2021 MDPI (Basel, Switzerland) unless otherwise stated Disclaimer The statements, opinions and data contained in the journals are solely those of the individual authors and contributors and not of the publisher and the editor(s). MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Terms and Conditions Privacy Policy
ISSN: 2076-3417
DOI: 10.3390/app11188276
Publisher site: See Article on Publisher Site

Abstract

applied sciences Review Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols 1 1 , 2 1 1 , 2 , 1 , 3 Oscar Vidal-Casanella , Oscar Núñez , Mercè Granados , Javier Saurina * and Sonia Sentellas Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, 08028 Barcelona, Spain; oscarvidalcasanella@gmail.com (O.V.-C.); oscar.nunez@ub.edu (O.N.); mgranados@ub.edu (M.G.); sonia.sentellas@ub.edu (S.S.) Research Institute in Food Nutrition and Food Safety, Recinte Torribera, University of Barcelona, 08921 Santa Coloma de Gramenet, Spain Serra Húnter Lecturer, Generalitat de Catalunya, 08007 Barcelona, Spain * Correspondence: xavi.saurina@ub.edu Featured Application: The relevance of phenolic acids, ﬂavonoids, and other polyphenols as the biologically active components of nutraceuticals is pointed out here. The principal analytical approaches to deal with their characterization and quantiﬁcation have been introduced as well, with liquid chromatography being the technique of choice in most cases. Abstract: Phenolic compounds such as phenolic acids, ﬂavonoids, and stilbenes comprise an enor- mous family of bioactive molecules with a range of positive properties, including antioxidant, antimicrobial, or anti-inﬂammatory effects. As a result, plant extracts are often puriﬁed to recover phenolic compound-enriched fractions to be used to develop nutraceutical products or dietary sup- plements. In this article, we review the properties of some remarkable plant-based nutraceuticals in which the active molecules are mainly polyphenols and related compounds. Methods for the Citation: Vidal-Casanella, O.; Núñez, characterization of these extracts, the chemical determination of the bioactivities of key molecules, O.; Granados, M.; Saurina, J.; and the principal applications of the resulting products are discussed in detail. Sentellas, S. Analytical Methods for Exploring Nutraceuticals Based on Keywords: polyphenols; ﬂavonoids; bioactive compounds; antioxidants; nutraceuticals; analyti- Phenolic Acids and Polyphenols. cal methods Appl. Sci. 2021, 11, 8276. https:// doi.org/10.3390/app11188276 Academic Editor: Andrea Salvo 1. Introduction The consumption of nutraceutical products and functional foods has experienced Received: 20 July 2021 enormous growth in the last decade due to the crucial role to help prevent some diseases, Accepted: 31 August 2021 as well as the positive effects for human health associated with the bioactive compounds Published: 7 September 2021 that they contain [1–3]. Among the different groups of phytochemicals, polyphenols are especially remarkable for several reasons, namely: (i) they are responsible for some Publisher’s Note: MDPI stays neutral organoleptic attributes of natural products, such as color, astringency, or bitterness [4]; (ii) with regard to jurisdictional claims in they are important descriptors of features of plants and derived products to be used as published maps and institutional afﬁl- biomarkers for quality control, classiﬁcation, and authentication purposes [5]; (iii) there is iations. solid evidence that the consumption of phenolic compounds found in natural foods may lower the risk of suffering health disorders thanks to their antioxidant capacities [2,3,6]. The last point is the most important regarding this paper as it refers to the beneﬁcial and healing properties of this great family of molecules. Copyright: © 2021 by the authors. Polyphenols comprise a large family of secondary metabolites of plants that are Licensee MDPI, Basel, Switzerland. especially abundant in red berries, chocolate, tea, wine, and fresh fruits, displaying con- This article is an open access article centrations that may vary from milligrams to grams per kilogram depending on the cases. distributed under the terms and The regular intake of these foods constitutes the main source of polyphenols for the human conditions of the Creative Commons diet. However, given the great interest of polyphenols, their natural sources are often ex- Attribution (CC BY) license (https:// ploited to obtain enriched and/or puriﬁed extracts with potential applications to cosmetics, creativecommons.org/licenses/by/ nutraceuticals, food supplements, and medicines. 4.0/). Appl. Sci. 2021, 11, 8276. https://doi.org/10.3390/app11188276 https://www.mdpi.com/journal/applsci Appl. Sci. 2021, 11, x FOR PEER REVIEW 2 of 17 Appl. Sci. 2021, 11, 8276 2 of 16 exploited to obtain enriched and/or purified extracts with potential applications to cos- metics, nutraceuticals, food supplements, and medicines. In particular, polyphenols may protect the organism against oxidative damage, thus In particular, polyphenols may protect the organism against oxidative damage, thus limiting the risk of several degenerative diseases related to the harmful action of free limiting the risk of several degenerative diseases related to the harmful action of free rad- radicals such as cancer, diabetes, and osteoporosis [2,6]. Beyond this generic antioxidant icals such as cancer, diabetes, and osteoporosis [2,6]. Beyond this generic antioxidant ac- action, more speciﬁc antiviral, antimicrobial, or anti-inﬂammatory properties attributed to tion, more specific antiviral, antimicrobial, or anti-inflammatory properties attributed to given compounds have been reported as well [7–10]. Speciﬁc examples are given in the given compounds have been reported as well [7–10]. Specific examples are given in the following sections. following sections. 2. Polyphenols and Related Compounds 2. Polyphenols and Related Compounds They are primarily synthesized as signaling and defensive molecules against external They are primarily synthesized as signaling and defensive molecules against external stressors, such as climatic and environmental factors (drought, high temperature, solar stressors, such as climatic and environmental factors (drought, high temperature, solar radiation, and pollution) and pathogens, thus allowing plants to respond promptly to radiation, and pollution) and pathogens, thus allowing plants to respond promptly to multiple aggressions of different origins [11,12]. Strictly speaking, polyphenols consist of multiple aggressions of different origins [11,12]. Strictly speaking, polyphenols consist of organic compounds containing several phenolic groups. Other related compounds are organic compounds containing several phenolic groups. Other related compounds are sometimes included under this generic designation so that, in a broader context, the family sometimes included under this generic designation so that, in a broader context, the fam- of polyphenols and related compounds is as follows: phenolic acids, ﬂavonoids, stilbenes, ily of polyphenols and related compounds is as follows: phenolic acids, flavonoids, stil- lignans, as well as a more heterogeneous group of structurally related compounds such as benes, lignans, as well as a more heterogeneous group of structurally related compounds chalcones, humulones, and alcohols [12,13]. such as chalcones, humulones, and alcohols [12,13]. The number of polyphenol molecules that have been reported, identiﬁed, or character- The number of polyphenol molecules that have been reported, identified, or charac- ized is close to 9000. A brief explanation of the four main classes is given as follows (see terized is close to 9000. A brief explanation of the four main classes is given as follows (see Figure 1): Figure 1): Figure 1. Classiﬁcation of polyphenols according to their structures with some representative molecules of each family. Figure 1. Classification of polyphenols according to their structures with some representative molecules of each family. (i) Phenolic acids comprise hydroxybenzoic and hydroxycinnamic acids. They account (i) Phenolic acids comprise hydroxybenzoic and hydroxycinnamic acids. They account for 30% of the total dietary phenolics, and, in general, cinnamic derivatives, such as for 30% of the total dietary phenolics, and, in general, cinnamic derivatives, such as caffeic, ferulic, and coumaric acids, are more abundant than the benzoic ones. Tartaric caffeic, ferulic, and coumaric acids, are more abundant than the benzoic ones. Tar- esters of these acids (e.g., caftaric and coutaric acids) are especially abundant in grape, taric esters of these acids (e.g., caftaric and coutaric acids) are especially abundant in vine, and wines. In addition, quinic acid derivatives such as chlorogenic acids are present in a broad range of products (e.g., coffee, tea, and pear). Phenolic acids also include hydrolyzable tannins, which consist of sugar residues esteriﬁed with gallic or Appl. Sci. 2021, 11, 8276 3 of 16 ellagic acids. This type of tannin can be found at 10 to 100 mg kg levels in coffee, fruits, nuts, tea, and wine. (ii) Flavonoids are the largest family of polyphenols both qualitatively and quantitatively as more than 5000 different molecules have been described, accounting for 60% of the total dietary polyphenols in humans [14]. The ﬂavonoid backbone consists of two aromatic rings connected through a linking heterocycle with an oxygen and three carbon atoms (C6-C3-C6 skeleton). Flavonoids can be divided into six subclasses, namely: ﬂavonols, ﬂavones, isoﬂavones, ﬂavanones, anthocyanidins, and ﬂavanols. Additional details are given below. Flavonols are based on the hydroxyﬂavone backbone in which the phenyl residues can be variedly hydroxylated (or methoxylated), thus resulting in various remarkable aglycones such as quercetin, kaempferol, ﬁsetin, and morin [15–17]. In nature, they are predominantly linked to sugars as a way to enhance their solubility in intra- and extracellular media. Hence, glucosides, galactosides, rhamnosides, and rutinosides are frequently found in plant matrices. Although ﬂavonols are found at low concentrations, they play fundamental roles in growth regulation mechanisms. Flavones consist of the 2-phenylchromen-4-one backbone, structurally similar to ﬂavonols but without the hydroxyl group [18,19]. Some representative molecules are api- genin, luteolin, and tangeritin, generally occurring at levels below 1 mg kg in vegetables such a broccoli, celery, carrot, parsley, or spinach. C- and O-glycosides have been reported in cereals such as sorghum and millet at levels from 0.05 to 10 mg kg . Isoﬂavones are also based on the 2-phenylchromen-4-one backbone, differing from the ﬂavones in the position of the phenyl group. Isoﬂavones are almost speciﬁc to the Fabaceae family, occurring at concentrations of 1 mg kg in soybean, chickpea, peanut, and sunﬂower seeds [20,21]. Some typical aglycones are daidzin and genistin, often glycosided to a high extent. Despite their low concentrations in natural sources, they have great interest due to their structural resemblance with steroid hormones. Hence, isoﬂavones act as estrogens to alleviate postmenopausal effects (e.g., hot ﬂashes and bone loss) in women and to lower cholesterol levels in blood. Flavanones consist of ﬂavan-4-one structures without the double bond in the het- erocycle so that they have chiral carbons. As in the other cases, phenyl rings display varied hydroxylation (and methoxylation), with some representative aglycones being hesperetin, naringenin, taxifolin, and eriodictyol. They are predominantly combined with saccharides, resulting in compounds such as hesperidin, naringin, or narirutin. Fla- vanones are the main polyphenols in species of the Citrus genus, reaching concentrations of 100 to 3000 mg kg [22]. The main ﬂavanone bioactivities deal with the antioxidant and radical scavenging power, thus being used as prophylactics to reduce the risk of cancer and cardiovascular diseases. Anthocyanidin aglycones and anthocyanin glycosides are charged species containing the ﬂavylium cation (the oxygen of the heterocycle is an oxonium cation). The principal aglycones (e.g., cyanidin, delphinidin, malvidin, and pelargonidin) are often attached to sugars. They are the largest group of pigments found in nature responsible for the cyan and red colors of berries, grapes, tomatoes, and wine [23]. Flavanols, also referred to as ﬂavan-3-ols or catechins, are one of the most important families of polyphenols from both quantitative and qualitative issues [24–26]. Flavanols are present in high amounts in cocoa, coffee, fruits (berries, grapes, pears, and apples), legumes (peas, lentils, and beans), nuts (walnut, hazelnut, and peanut), and tea. For example, overall concentrations in fresh fruits are about 50 to 250 mg kg , reaching even 1 1 higher values in green tea (ca. 700 mg kg ) and cocoa (ca. 2000 mg kg ). As ﬂavanones, the heterocycle lacks the double bond so that they have chiral carbons. ()-Epicatechin and (+)-catechin, ()-epigallocatechin, ()-epicatechin gallate, and ()-epigallocatechin gallate are the most remarkable ﬂavanols. They are prone to condense to form the so- called proanthocyanidins (PACs) or condensed tannins, which consist of two or several ﬂavonoid moieties attached in different ways, thus resulting in dimers, trimers, and larger Appl. Sci. 2021, 11, 8276 4 of 16 oligomers [9,27]. Monomers are often connected via the C4 of the upper unit with the C6 or C8 of the lower counterpart (B-type bond). However, in speciﬁc cases, they have an additional link between the C2 of the upper monomer and the hydroxyl group of C5 or C7 of the lower one (i.e., C2-O-C5 or C2-O-C7), thus resulting in the so-called A-type bond. As detailed below, B-type compounds are more abundant in nature but the A-type ones possess a noticeable antimicrobial activity [28]. (iii) Stilbenes are characterized by a double-bond connecting two aromatic rings. Despite being found in low quantities in the human diet, the signiﬁcance of compounds such as trans-resveratrol is outstanding. Apart from the more controversial antiaging effects, chemopreventive, chemotherapeutic, cardioprotective, and neuroprotective beneﬁts have been attributed to resveratrol and its derivatives [29]. Curcuminoids are structurally related stilbenoids exhibiting a great range of nutritional and health beneﬁcial properties [30]. Their structure has been used as the basis to design new drugs for the treatment of several types of cancers and microbial infections [30]. (iv) Lignans are a minor class of polyphenols consisting of two phenylpropane units. The main food source of lignans is linseed, although they are also found at lower concentrations in cereals, fruits, and vegetables [31]. Recently, lignans have at- tracted the attention of researchers because of their potential anti-inﬂammatory, anti-neurodegenerative, antiviral, antimicrobial, and phytoestrogenic activities. 3. Nutraceuticals from Plant Extracts A type of trendy nutraceutical and dietary supplement consists of mixtures of fruit and medicinal plant extracts such as American cranberry and other red and blackberries, turmeric, grapevine, and green tea, with exceptional detoxifying, antiaging, and antioxidant features [32]. American cranberry (Vaccinium macrocarpon) is rich in a wide variety of phytochemi- cals such as saccharides, carotenoids, phenolic acids, and ﬂavonoids [33,34]. Fresh berries, raisins, and powdered extracts have been used as natural remedies to treat inﬂammatory and microbial processes. Other properties have also been recognized, including antineo- plastic, cardioprotective, or antidegenerative activities [35,36]. Regarding antimicrobial issues, A-type PACs are the main compounds to be used for the prophylaxis and treat- ment of urinary tract infections (UTIs). The bioactivity of these species is attributed to their planar structure, which may create a protecting barrier on the urinary tract walls, thus avoiding the adhesion of bacteria [9]. Cranberry extracts are sometimes combined with other medicinal plants such as Salvia ofﬁcinalis, Urtica urens, or Solidago virgaurea that provide additional anti-inﬂammatory and diuretic properties to facilitate the excretion of urine. Another group of nutraceuticals is focused on products to reduce weight and control obesity [37]. For this purpose, raspberry (Rubus idaeus) and green tea (Camellia sinensis) ex- tracts have been widely used, often combined in the same pharmaceutical form in slimming treatments [38,39]. Raspberry contains phenolic ketones (e.g., 4-phenylbutan-2-one) that activate the fat metabolism, while green tea is rich in caffeine and epigallocatechin with fat- burning properties. Adjuvant plant extracts with diuretic activity are sometimes included in the composition of this type of product to reinforce the feeling of weight reduction. Preparations based on grape (Vitis vinifera) extracts are highly rich in phenolic acids, ﬂavonoids, and stilbenes. Their high antioxidant power is undeniable, thus making grape extracts very healthy [40]. Grapevine is another product derived from Vitis vinifera rich in resveratrol and many other polyphenols, such as rutinosides, with cardioprotective and anti-inﬂammatory properties to be used in venous insufﬁciency [41]. Nutraceuticals made with artichoke (Cynara scolymus) possess hypolipidemic, detox, and hepatoprotective indications. Artichoke extracts contain high amounts of phenolic acids, sesquiterpenic lactones, and ﬂavonoids as the principal bioactive compounds [42,43]. Soya (Glycine max), as well as other members of Fabaceae, has been used traditionally in multiple nutraceutical products. The high content in polyphenols provides antioxidant, Appl. Sci. 2021, 11, 8276 5 of 16 antimicrobial, and hypolipidemic activity. However, its estrogenic property is probably the most remarkable attribute [20,21]. Hence, soya-based capsules containing puriﬁed extracts of isoﬂavones are widely used to treat menopausal symptoms. Turmeric (Curcuma longa) belongs to the ginger family, used for centuries as a remedy in traditional Asian pharmacy, as well as a valuable condiment in cuisine. Turmeric extracts or powders of dry rhizome are appreciated due to their antioxidant and anti- inﬂammatory activities. Turmeric is sometimes combined with other species such as ginger, garlic, and cinnamon for both nutraceutical and culinary purposes. Curcumin and related curcuminoids are the main bioactive compounds of turmeric [7]. Finally, a more diverse group of samples commercialized under detoxifying attributes has also been studied, consisting of mixtures of fruit extracts (Vaccinium corymbosum, Fragaria vesca, Vaccinium macrocarpom, Rubus idaeus, Ribes nigrum, Vaccinium myrtillus, Ruscus aculeatus, and Punica granatum) and some medicinal plants (e.g., Aesculus hippocastanum and Hamamelis virginiana). These preparations contain noticeable amounts of ﬂavanols (catechin, epicatechin, and procyanidin B2), as well as other phenolic acids and ﬂavonoids, providing great antioxidant, antimicrobial, anti-inﬂammatory effects [3]. 4. Analytical Methods for the Determination of Active Compounds in Nutraceutical Products In this section, an introduction to the principal approaches for the determination of active phenolic compounds in the nutraceutical samples is given. 4.1. Spectroscopic Methods 4.1.1. Antioxidant Indexes Colorimetric assays are broadly used to determine the antioxidant capacity (AC) in nutraceuticals, which is mainly related to the presence of phenolic compounds. Although there is some controversy about the reliability of AC values obtained by these in vitro chemical assays, they are simple and require cheap equipment, which makes them an attractive approach to estimate AC. Among the most used, we can highlight the assays of Folin–Ciocalteu, ferric reducing antioxidant power (FRAP), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and 2,2 -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) [6]. The assays are based on a redox reaction (e.g., Folin–Ciocalteu and FRAP), some of them involving a radical reagent (e.g., DPPH and ABTS), which leads to a change in the UV-visible spectrum of the solution. In all of the methods, the calibration is performed with an individual compound (e.g., gallic acid and Trolox) and AC is expressed in terms of the equivalent concentration of the compound used for calibration. The Folin–Ciocalteu (FC) method is, probably, the most applied to determine the total phenolic content, and it is considered a proper assay to estimate AC in samples of plant origin. The method was initially developed for the analysis of proteins and was later extended to the analysis of polyphenols [44] based on a redox reaction involving the reduction of Mo (VI) to blue Mo (V) under alkaline conditions. The FRAP test is based on 3+ the reduction of the Fe (III)-2,2,6-tripyridyl-s-triazine (TPTZ) complex (Fe (TPZT) ) to the 2+ Fe (II)-TPTZ complex (Fe (TPZT) ), which has an intense blue color [45,46]. The FRAP assay is very simple and rugged, provided that the time elapsed between the start of the reaction and the measurements is kept under control. A large number of FRAP data of plant products can be found in the literature [47]. Other ligands (e.g., Fe (CN) ) have also been proposed to develop alternative colorimetric reactions. Regarding radical-based reactions, the DPPH assay is related to the scavenging activity of antioxidants against the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) [45]. DPPH is a stable radical, commercially available, and its solutions are violet in color, with an absorption maximum at 517 nm. The reduced form (DPPH-H) has a pale yellow color. Thus, when DPPH is reduced to DPPH-H by an antioxidant, the absorbance of the solution decreases. Although the method is widely applied to estimate AC, DPPH is not the best option for samples rich in anthocyanins, such as berries, cherries, and plums, because these Appl. Sci. 2021, 11, x FOR PEER REVIEW 6 of 17 Regarding radical-based reactions, the DPPH assay is related to the scavenging ac- tivity of antioxidants against the 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) [45]. DPPH is a stable radical, commercially available, and its solutions are violet in color, with Appl. Sci. 2021, 11, 8276 6 of 16 an absorption maximum at 517 nm. The reduced form (DPPH-H) has a pale yellow color. Thus, when DPPH is reduced to DPPH-H by an antioxidant, the absorbance of the solu- tion decreases. Although the method is widely applied to estimate AC, DPPH is not the best option for samples rich in anthocyanins, such as berries, cherries, and plums, because compounds absorb in a similar range of wavelengths and interfere. The ABTS method is these compounds absorb in a similar range of wavelengths and inter + fere. The ABTS based on the scavenging activity of antioxidants against the ABTS radical cation, whose method is based on the scavenging activity of antioxidants against the ABTS radical cat- solutions have a dark blue color. ABTS is not commercially available and has to be ion, whose solutions have a dark b0lue color. ABTS is not commercially available and has generated by the oxidation of 2,2 -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) to be generated by the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) with peroxodisulfate [45]. A lot of AC data from ABTS assays for a wide variety of plant (ABTS) with peroxodisulfate [45]. A lot of AC data from ABTS assays for a wide variety samples have been reported [47]. of plant samples have been reported [47]. The comparison of results from different assays is not a trivial issue, as the sensitivity The comparison of results from different assays is not a trivial issue, as the sensitivity of each particular reducing species in each method is characteristic of the compound [48]. of each particular reducing species in each method is characteristic of the compound [48]. Figure 2, adapted from Reference [48] by Alcalde et al., compared various antioxidant Figure 2, adapted from Reference [48] by Alcalde et al., compared various antioxidant indexes for the series of hydroxybenzoic acids. Despite the structural similarity of these indexes for the series of hydroxybenzoic acids. Despite the structural similarity of these molecules, the antioxidant powers differed signiﬁcantly. The higher activities seemed to molecules, the antioxidant powers differed significantly. The higher activities seemed to be associated with the presence of more than one hydroxyl group conveniently oriented be associated with the presence of more than one hydroxyl group conveniently oriented in ortho or para positions, while those in meta or monohydroxylated species were less in ortho or para positions, while those in meta or monohydroxylated species were less ac- active. Hence, the strongest reducing agents according to the FC assay were dihydroxy- tive. Hence, the strongest reducing agents according to the FC assay were dihydroxy- and and trihydroxybenzoic acids with o- and p-conﬁgurations, while those not following this trihydroxybenzoic acids with o- and p-configurations, while those not following this pat- pattern were less efﬁcient. tern were less efficient. Figure 2. Figure 2.Comparison of anti Comparison of antioxidant oxidant indexe indexes s for the se for theriseries es of h of ydhydr roxyb oxybenzoic enzoic acids acids. . Data c Data orrecorr - e- spond to the normalized slopes of the calibration curves of each analyte and each method. Com- spond to the normalized slopes of the calibration curves of each analyte and each method. Com- pound assignation: 3-HBA, 3-hydroxybenzoic acid; 4-HBA, 4-hydroxybenzoic acid; 2,4-DHBA, 2,4- pound assignation: 3-HBA, 3-hydroxybenzoic acid; 4-HBA, 4-hydroxybenzoic acid; 2,4-DHBA, dihydroxybenzoic acid; 3,5-DHBA, 3,5-dihydroxybenzoic acid; 2,5-DHBA, 2,5-dihydroxybenzoic 2,4-dihydroxybenzoic acid; 3,5-DHBA, 3,5-dihydroxybenzoic acid; 2,5-DHBA, 2,5-dihydroxybenzoic acid; 2,3-DHBA, 2,3-dihydroxybenzoic acid; 3,4-DHBA, 3,4-dihydroxybenzoic acid; 2,4,6-THBA, acid; 2,3-DHBA, 2,3-dihydroxybenzoic acid; 3,4-DHBA, 3,4-dihydroxybenzoic acid; 2,4,6-THBA, 2,4,6- 2,4,6-trihydroxybenzoic acid; 2,3,4-THBA, 2,3,4-trihydroxybenzoic acid; gallic acid, 3,4,5-trihy- trihydroxybenzoic acid; 2,3,4-THBA, 2,3,4-trihydroxybenzoic acid; gallic acid, 3,4,5-trihydroxybenzoic droxybenzoic acid. Method assignation: FC, Folin–Ciocalteau; FRAP, ferric reducing antioxidant acid. Method assignation: FC, Folin–Ciocalteau; FRAP, ferric reducing antioxidant power; DPPH, power; DPPH, 2,-diphenyl-1-picrylhydrazyl; ABTS, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sul- fonic a 2,-diphenyl-1-picrylhydrazyl; cid)(adapted from reference [48]) ABTS, 2,2 . -azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(adapted from reference [48]). In any case, it is recommended to apply several spectroscopic methods based on dif- ferent mech In any ancase, isms tit o achi is recommended eve complement toary apply inform several ation t spectr o evaloscopic uate the AC o methods f sample based s. on different mechanisms to achieve complementary information to evaluate the AC of samples. 4.1.2. Flavonoid Assays Apart from the indexes that provide information about the total AC, some assays focus on families of ﬂavonoids, such as the aluminum complexation assays, or the 4- dimethylaminocinnamaldehyde (DMAC) spectrophotometric method. For instance, ﬂavonols and ﬂavones form yellow complexes with Al(III) at neutral pH, and the absorbance of the solution is measured in the 400–430 nm range. Furthermore, Al(III) forms red complexes with some ﬂavonoids (e.g., rutin, luteolin, and catechins) in Appl. Sci. 2021, 11, x FOR PEER REVIEW 7 of 17 4.1.2. Flavonoid Assays Apart from the indexes that provide information about the total AC, some assays focus on families of flavonoids, such as the aluminum complexation assays, or the 4-di- methylaminocinnamaldehyde (DMAC) spectrophotometric method. Appl. Sci. 2021, 11, 8276 7 of 16 For instance, flavonols and flavones form yellow complexes with Al(III) at neutral pH, and the absorbance of the solution is measured in the 400–430 nm range. Furthermore, Al(III) forms red complexes with some flavonoids (e.g., rutin, luteolin, and catechins) in the presence of sodium nitrite in an alkaline medium, and the absorbance of the solution is the presence of sodium nitrite in an alkaline medium, and the absorbance of the solution measured at 510 nm [49]. is measured at 510 nm [49]. Currently, DMAC is the most popular reagent for the quantiﬁcation of the overall PAC Currently, DMAC is the most popular reagent for the quantification of the overall content in nutraceuticals and functional foods. DMAC is an aromatic aldehyde that, under PAC content in nutraceuticals and functional foods. DMAC is an aromatic aldehyde that, strongly acidic conditions, reacts with ﬂavanols via the formation of a reactive electrophilic under strongly acidic conditions, reacts with flavanols via the formation of a reactive elec- carbocation. The DMAC reaction is speciﬁc to ﬂavanols and their gallates. DMAC reacts trophilic carbocation. The DMAC reaction is specific to flavanols and their gallates. with the C8 position of the terminal unit to form a green chromophore with maximum DMAC reacts with the C8 position of the terminal unit to form a green chromophore with absorbance at ca. 640 nm. Hence, interferences from the colored anthocyanidins can be maximum absorbance at ca. 640 nm. Hence, interferences from the colored anthocyanidins avoided [50–53]. PACs with a high degree of polymerization (DP) have lower responses can be avoided [50–53]. PACs with a high degree of polymerization (DP) have lower re- per unit weight than monomers and dimers [28,50,54]. sponses per unit weight than monomers and dimers [28,50,54]. 4.2. Voltammetric Methods 4.2. Voltammetric Methods Electroanalytical techniques such as cyclic voltammetry (CV) and differential pulse Electroanalytical techniques such as cyclic voltammetry (CV) and differential pulse voltammetry (DPV) have been widely used for the detection of polyphenols. A direct voltammetry (DPV) have been widely used for the detection of polyphenols. A direct re- relationship between the concentration of electroactive functional groups and the current lationship between the concentration of electroactive functional groups and the current intensity generated is often found when they are either oxidized or reduced at the working intensity generated is often found when they are either oxidized or reduced at the work- electrode surface [55–57]. ing electrode surface [55–57]. The techniques commented above are especially recommended for the analysis of The techniques commented above are especially recommended for the analysis of polyphenols as their antioxidant properties are often related to the ability to donate elec- polyphenols as their antioxidant properties are often related to the ability to donate elec- trons. Voltammetric signals at low oxidation potentials suggest the presence of polypheno- trons. Voltammetric signals at low oxidation potentials suggest the presence of polyphe- lics of high antioxidant activity, whereas those compounds with low antioxidant power nolics of high antioxidant activity, whereas those compounds with low antioxidant power show electrochemical activity at more positive potentials [55,57]. Regarding electrodes, show electrochemical activity at more positive potentials [55,57]. Regarding electrodes, recent studies to determine polyphenols in nutraceuticals and related samples have re- recent studies to determine polyphenols in nutraceuticals and related samples have relied lied on a wide variety of working electrodes, such as the pencil-graphite electrode (PGE), on a wide variety of working electrodes, such as the pencil-graphite electrode (PGE), glassy carbon electrode (GCE), platinum (Pt), and different types of biosensors. In gen- glassy carbon electrode (GCE), platinum (Pt), and different types of biosensors. In general, eral, Pt has been used as an auxiliary electrode and Ag/AgCl (3 M KCl) as the reference Pt has been used as an auxiliary electrode and Ag/AgCl (3 M KCl) as the reference elec- electrode [55,57–59]. trode [55,57–59]. Some representative examples are depicted in Figure 3, which shows the differential Some representative examples are depicted in Figure 3, which shows the differential pulse voltammograms recorded in the range from0.2 to + 0.9 V vs. an Ag|AgCl|KCl ref- pulse voltammograms recorded in the range from −0.2 to + 0.9 V vs. an Ag|AgCl|KCl erence electrode. In the case of catechin, with two independent dihydroxyphenyl moieties, reference electrode. In the case of catechin, with two independent dihydroxyphenyl moi- two oxidation peaks corresponding to each side of the molecule have been detected. eties, two oxidation peaks corresponding to each side of the molecule have been detected. Figure 3. Differential pulse voltammograms recorded in the range from 0.2 to + 0.9 V vs. an Ag|AgCl|KCl reference Figure 3. Differential pulse voltammograms recorded in the range from −0.2 to + 0.9 V vs. an Ag|AgCl|KCl reference electrode for three representative examples: (a) 3,4-dihydroxybenzoic acid; (b) 2,4-dihydroxybenzoic acid; (c) catechin electrode for three representative examples: (a) 3,4-dihydroxybenzoic acid; (b) 2,4-dihydroxybenzoic acid; (c) catechin (adapted from reference [48]). (adapted from reference [48]). These techniques result in powerful alternatives to traditional spectrophotometric measurements due to the high sampling throughput, simplicity, sensitivity, reduced sample, and reagent consumption. However, one of the main issues of voltammetric studies is related to the electrode fouling during the measurements due to the adsorption of several nutraceutical sample components. In such circumstances, a cleaning step may be necessary before each voltammetric measurement to clean or renew the electrode surface [55,57,58,60]. Appl. Sci. 2021, 11, 8276 8 of 16 Some representative examples are mentioned as follows. For instance, grape extracts analyzed by CV with GCE showed a ﬁrst oxidation peak at 420 mV corresponding to the catechol group on the B-ring of ﬂavanols, and a second oxidation peak at 800–860 mV belonging to the resorcinol group on the A-ring [56]. In another study, the determination of TPC in Turkish green, black, and white tea extracts using DPV allowed a sensitive, rapid, and inexpensive evaluation of samples, with recoveries of caffeic acid around 95% [59]. In addition, DPV and CV were demonstrated to be appropriate to express the antioxidant activity of coffee extracts, presenting good correlations with DPPH spectrophotometric results [60]. 4.3. Chromatographic Methods Beyond the spectroscopic and voltammetric methods that provide information on the overall content of polyphenols, separation methods offer excellent opportunities for proﬁling. Thus, chromatographic techniques result in the best option for the simultaneous quantiﬁcation of several bioactive components occurring in the samples. Among the arsenal of techniques available in our current analytical laboratories, liquid chromatography seems to be the system of choice. Capillary electrophoresis (CE) can also be used owing to the ionizable nature of polyphenols. For instance, the phenolic content of herbal, fruit, or vegetable extracts has been determined using different CE modes such as capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), capillary isotachophoresis (CITP), and capillary electrochromatography (CEC) [61–65]. The polar and thermolabile nature of polyphenols hinders the use of gas chromatog- raphy (GC) for their direct determination. Hence, GC methods for the determination of polyphenols rely on derivatization procedures to reduce the polarity of analytes. In this regard, silylation has been successfully applied to the identiﬁcation and quantiﬁcation of phenolic compounds in plant and fruit extracts [66–69]. As mentioned, liquid chromatography (LC) is the best option for the determination of polyphenols in nutraceutical products and in plant extracts. In general, phenolic acids, stilbenes, and ﬂavonoids can be separated successfully by reversed-phase (RP) mode, typically with C18 or C8 columns. Beyond conventional High Performance LC (HPLC), the newest and most powerful instrumentation based on ultra-high-performance liquid chromatography (UHPLC) and core–shell column technology can be used. Mobile phases in LC are prepared with MeOH or ACN as organic solvents and acid aqueous solutions (e.g., using formic or acetic acids). The high complexity of the nutraceu- tical samples often requires customized elution gradients to achieve a good resolution of components. For instance, up to 15 polyphenols were determined in Taurisolo (grape pomace extract supplement, MBMed, Turin, Italy) using a polar RP-C18 HPLC column and an elution gradient generated with 0.1% formic acid in water (v/v) and acetonitrile [70]. López-Gutierrez et al. determined more than 30 polyphenol-related compounds in nu- traceutical samples (tablets and capsules) derived from green tea and grapes. The UHPLC separation was accomplished with sub-2 m particle-size C18 columns together with mass spectrometry (MS) detection [71,72]. To avoid expensive instrumental platforms, core–shell columns appeared as a good alternative to achieve excellent efﬁcacies. In this regard, Bakhytkyzy et al. used a Kinetex C18 reversed-phase (100 mm 4.6 mm ID, 2.6-m particle size) column for the determina- tion of ﬂavanols in dietary products and pharmaceuticals [73]. In another example, sub-2 m and porous-shell columns were compared for the determination of 29 polyphenols in cranberry-based pharmaceuticals obtaining, in that case, better performances using the UHPLC option [74]. As an alternative to the reverse-phase mode, the hydrophilic interaction chromatogra- phy (HILIC) has opened up great possibilities, especially for dealing with the most polar analytes that are weakly retained in RP columns. HILIC was used, for example, for the separation of ﬂavanols and related compounds in dietary supplements and nutraceuticals from berries, grapes, or artichoke extracts [75] (see Figure 4). The mobile phase consisted Appl. Sci. 2021, 11, x FOR PEER REVIEW 9 of 17 2 µm and porous-shell columns were compared for the determination of 29 polyphenols in cranberry-based pharmaceuticals obtaining, in that case, better performances using the UHPLC option [74]. As an alternative to the reverse-phase mode, the hydrophilic interaction chromatog- raphy (HILIC) has opened up great possibilities, especially for dealing with the most polar Appl. Sci. 2021, 11, 8276 9 of 16 analytes that are weakly retained in RP columns. HILIC was used, for example, for the separation of flavanols and related compounds in dietary supplements and nutraceuticals from berries, grapes, or artichoke extracts [75] (see Figure 4). The mobile phase consisted of acidified acetonitrile and methanol solutions, applying an elution gradient based on of acidiﬁed acetonitrile and methanol solutions, applying an elution gradient based on increasing the percentage of methanol. In this study, the authors highlighted the im- increasing the percentage of methanol. In this study, the authors highlighted the improved proved separation of flavanol oligomers, as well as the great potential to separate small separation of ﬂavanol oligomers, as well as the great potential to separate small phenolic phenolic acid molecules. acid molecules. Figure 4. Representative chromatograms of various nutraceutical samples obtained by HILIC-FLD. Figure 4. Representative chromatograms of various nutraceutical samples obtained by HILIC-FLD. Sample assignation: a = antioxidant extract; b = cranberry; c = cranberry (combined); d = artichoke; Sample assignation: a = antioxidant extract; b = cranberry; c = cranberry (combined); d = artichoke; e = red grape (peel and seeds); f = raspberry; g = grapevine. Compound assignation: 1 = catechin; 2 e = red grape (peel and seeds); f = raspberry; g = grapevine. Compound assignation: 1 = catechin; = epicatechin; 3 = procyanidin A2; 4 = procyanidin B2; 5 = trimer 1; 6 = procyanidin C1; 7 = tetramer 2 = epicatechin; 3 = procyanidin A2; 4 = procyanidin B2; 5 = trimer 1; 6 = procyanidin C1; 7 = tetramer 1; 8 = tetramer 2; 9 = pentamers; 10 = hexamers (adapted from reference [75]). 1; 8 = tetramer 2; 9 = pentamers; 10 = hexamers (adapted from reference [75]). The LC × LC strategy, combining different stationary phases, namely RP (or modified The LC LC strategy, combining different stationary phases, namely RP (or modiﬁed RP), HILIC, and, less commonly, size-exclusion chromatography (SEC), has shown to be RP), HILIC, and, less commonly, size-exclusion chromatography (SEC), has shown to promising for the determination of polyphenols in food products [76,77]. LC × LC, oper- be promising for the determination of polyphenols in food products [76,77]. LC LC, ating in the off-line or on-line modes, offers improved separations taking advantage of the operating in the off-line or on-line modes, offers improved separations taking advantage of orthogonality between the first and second dimensions. Consequently, sample clean-up the orthogonality between the ﬁrst and second dimensions. Consequently, sample clean-up procedures can be simplified by reducing the total analysis time. In this regard, an RP-LC procedures can be simpliﬁed by reducing the total analysis time. In this regard, an RP-LC × RP-LC method, combining a micro-bore ES-CN column (1D) with a C18 column (2D), RP-LC method, combining a micro-bore ES-CN column (1D) with a C18 column (2D), was successfully applied to the determination of 51 polyphenolic compounds in pistachio was successfully applied to the determination of 51 polyphenolic compounds in pistachio extracts [78]. Another study performed by Sommella et al. for the determination of poly- extracts [78]. Another study performed by Sommella et al. for the determination of polyphe- phenols in apple extracts samples combined HILIC × RP in the two-dimensional LC [79]. nols in apple extracts samples combined HILIC RP in the two-dimensional LC [79]. In In this case, higher peak capacities and sensitivities were obtained with the optimized this case, higher peak capacities and sensitivities were obtained with the optimized online online HILIC × RP-UHPLC-MS method concerning previously 1D reported methods. HILIC RP-UHPLC-MS method concerning previously 1D reported methods. Regarding detection, apart from the widespread UV-vis spectroscopy, fluorescence Regarding detection, apart from the widespread UV-vis spectroscopy, ﬂuorescence and mass spectrometry have been utilized to increase the sensitivity and selectivity of the and mass spectrometry have been utilized to increase the sensitivity and selectivity of the methods. In UV-Vis, current multi-way spectrophotometers such as diode-array detectors methods. In UV-Vis, current multi-way spectrophotometers such as diode-array detectors allow the simultaneous detection of the different phenolic families. For instance, the range allow the simultaneous detection of the different phenolic families. For instance, the 270–280 nm is used to monitor benzoic acids, flavanols, flavanones, and other species con- range 270–280 nm is used to monitor benzoic acids, ﬂavanols, ﬂavanones, and other taining phenyl moieties, 310–330 nm is used for hydroxycinnamic acids and stilbenes, species containing phenyl moieties, 310–330 nm is used for hydroxycinnamic acids and 370–380 nm is used for flavones, isoflavones, and flavonols, 420–430 nm is used for cur- stilbenes, 370–380 nm is used for ﬂavones, isoﬂavones, and ﬂavonols, 420–430 nm is used cuminoids, and 450–550 nm is used for anthocyanins. for curcuminoids, and 450–550 nm is used for anthocyanins. As most of the polyphenolic compounds have ﬂuorescent moieties in their structures, ﬂuorometric detection is an excellent alternative to the UV counterpart, thus providing enhanced performance from a proper selection of the excitation and emission wavelengths. For instance, ﬂavanols are detected at 280 nm and 320 nm with negligible in- ex em terferences from other phenolic families; 325 nm and 375 nm are good choices ex em for the determination of hydroxycinnamic acids; 375 nm and 430 nm have been ex em recommended for ﬂavonols, ﬂavones, and isoﬂavones. Currently, MS is the most powerful detector for qualitative and quantitative deter- minations of phenolic compounds. In our opinion, the hyphenation of MS with liquid chromatography deserves a more exhaustive development. Hence, the state of the art of application of HPLC-MS to polyphenol characterization is given below. Appl. Sci. 2021, 11, x FOR PEER REVIEW 10 of 17 As most of the polyphenolic compounds have fluorescent moieties in their structures, fluorometric detection is an excellent alternative to the UV counterpart, thus providing enhanced performance from a proper selection of the excitation and emission wave- lengths. For instance, flavanols are detected at λex 280 nm and λem 320 nm with negligible interferences from other phenolic families; λex 325 nm and λem 375 nm are good choices for the determination of hydroxycinnamic acids; λex 375 nm and λem 430 nm have been rec- ommended for flavonols, flavones, and isoflavones. Currently, MS is the most powerful detector for qualitative and quantitative deter- minations of phenolic compounds. In our opinion, the hyphenation of MS with liquid Appl. Sci. 2021, 11, 8276 10 of 16 chromatography deserves a more exhaustive development. Hence, the state of the art of application of HPLC-MS to polyphenol characterization is given below. Liquid Chromatography Coupled to Mass Spectrometry Liquid Chromatography Coupled to Mass Spectrometry HPLC-MS techniques, and more recently, the UHPLC-MS counterparts, have been HPLC-MS techniques, and more recently, the UHPLC-MS counterparts, have been increasingly used in nutraceutical characterization, especially for bioanalytical applica- increasingly used in nutraceutical characterization, especially for bioanalytical applica- tions dealing with pharmacokinetics and metabolism studies. LC-MS has been widely ex- tions dealing with pharmacokinetics and metabolism studies. LC-MS has been widely ploited for the identification and structural elucidation of known and unknown bioactive exploited for the identiﬁcation and structural elucidation of known and unknown bioactive molecules, especially from LC-MS/MS experiments [80,81]. Furthermore, high-resolution molecules, especially from LC-MS/MS experiments [80,81]. Furthermore, high-resolution mass spectrometers (HRMS) coupled to the LC systems result in exceptional tools for food mass spectrometers (HRMS) coupled to the LC systems result in exceptional tools for food analysis. Obtaining accurate mass measurements is the major advantage of HRMS to pro- analysis. Obtaining accurate mass measurements is the major advantage of HRMS to vide almost unambiguous identifications and quantifications. For instance, the presence provide almost unambiguous identiﬁcations and quantiﬁcations. For instance, the presence of curcumin and other curcuminoids in turmeric-based extracts was confirmed using this of curcumin and other curcuminoids in turmeric-based extracts was conﬁrmed using this strategy. As can be seen in Figure 5, the accurate mass spectra obtained by LC-HRMS with strategy. As can be seen in Figure 5, the accurate mass spectra obtained by LC-HRMS an orbitrap analyzer gave the authors reliable information for the identification of curcu- with an orbitrap analyzer gave the authors reliable information for the identiﬁcation of min and other major components in the studied samples [82]. curcumin and other major components in the studied samples [82]. Figure 5. Reversed-phase liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) total ion Figure 5. Reversed-phase liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) total ion chromatogram (a) and extracted ion chromatogram of curcumin (m/z 367.1187) (b). MS spectrum of peak at retention time chromatogram (a) and extracted ion chromatogram of curcumin (m/z 367.1187) (b). MS spectrum of peak at retention time of 13.52 min (c). Adapted from reference [82]. of 13.52 min (c). Adapted from reference [82]. By far, ESI is the most generalized ionization source, although atmospheric-pressure By far, ESI is the most generalized ionization source, although atmospheric-pressure chemical ionization (APCI) has also been proposed, especially for those compounds ex- chemical ionization (APCI) has also been proposed, especially for those compounds exhibit- hibiting low ionization efficiencies under ESI conditions [83–85]. This is the case, for in- ing low ionization efﬁciencies under ESI conditions [83–85]. This is the case, for instance, of stance, of the identification and determination of triterpenes and phenolic acids from an- the identiﬁcation and determination of triterpenes and phenolic acids from ancient apples cient apples of Friuli Venezia Giulia as nutraceutical ingredients [85]. While ESI resulted of Friuli Venezia Giulia as nutraceutical ingredients [85]. While ESI resulted in the best option in the best for opt the i determination on for the deteof rminat phenolic ion of phenol acids, APCI ic ac in ids, negative APCI in ion negat mode ive was ion mode wa selected as s selected as the ion source of terpenes due to the opportunity to obtain the pseudomolec- the ion source of terpenes due to the opportunity to obtain the pseudomolecular [M-H] ions ular [M with -H] higher ions wi intensity th higher i than ntensi with ty ESI than [86 wi ].th Car ESotenoids I [86]. Carotenoi are also ds a atypical re also family a typica of l compounds family of com exhibiting pounds exh better ibiting bet ionization ter iobehavior nization beh under avior unde APCI conditions r APCI condit in comparison ions in com- to parison to ESI [84,87,88]. For example, Garzón et al. [84] described the determination of ESI [84,87,88]. For example, Garzón et al. [84] described the determination of carotenoids fr ca om rotenoi Araz dá s from Araz (Eugenia stipitate á (Eug ),en an ia st Amazonian ipitate), an fr Ama uit with zonian potential fruit wi value th potenti as a a nutraceutical l value as a sour nutrace ce. u Recently tical source , UHPLC-APCI-T . Recently, UHP OF/MS LC-APCI-TOF/M was also proposed S was also for pr theoposed screening for th of e scre genistein en- fr ing o om fselected genisteiseeds n from se of Apiaceae lected see [d 89 s o ]. f Apiaceae [89]. T To dat o date, e, doz dozens ens of appl of applications ications of (U of (U)HPLC-ESI-MS(/MS) )HPLC-ESI-MS(/MS) h have ave bee been n publishe published. d. Low- Low- resolution mass spectrometers based on triple quadrupole and ion trap analyzers are resolution mass spectrometers based on triple quadrupole and ion trap analyzers are typ- typically ically propos proposed ed forfor the se the nsit sensitive ive de determination termination ofof well well-known -known bioact bioactive ive sub substances, stances, aas s well as for identiﬁcation purposes when working in tandem mass spectrometry [90–94]. For example, Nzekoue et al. carried out the quantiﬁcation of 30 bioactive compounds in coffee silverskin extracts by HPLC-MS/MS using a triple quadrupole analyzer [94]. Eighteen phenolic compounds were detected and quantiﬁed, with caffeoylquinic acids being the most abundant ones. In contrast, HPLC-DAD-MS using an ion-trap analyzer was employed to address a comprehensive characterization of the phytochemicals present in an Italian ancient apple “Mela Rosa dei Monti Sibillini” [93]. Extracts from lyophilized material were richer in polyphenolic compounds than the dried counterparts. These ﬁndings suggested that this ancient apple variety was an excellent source of active components for nutraceuticals. HRMS based on time-of-ﬂight (TOF) and Orbitrap analyzers is the technique of choice for a comprehensive characterization of plant-based extracts due to the higher-resolution Appl. Sci. 2021, 11, 8276 11 of 16 capabilities and the accurate mass measurements (with errors below 2 ppm depending on the instrument). In these cases, hybrid conﬁgurations combining quadrupole and ion-trap analyzers coupled with HRMS instruments such as Q-TOF [95–100], IT-TOF [101], and Q-Orbitrap [102,103] were preferred to take advantage of the high sensitivity of these platforms under full-scan acquisition mode. Furthermore, fragmentations can be employed for identiﬁcation purposes, especially when proﬁling strategies are applied. For instance, Amat-ur-Rasool et al. evaluated the potential nutraceutical properties of leaves from sev- eral commonly cultivated plants such as lemon (Citrus limon), red silk-cotton (Bombax ceiba), henna (Lawsonia inermis), eucalyptus (Eucalyptus globulus), basil (Ocimum basilicum), Mandarin orange (Citrus reticulata), and spearmint (Mentha spicata) [95]. RP HPLC cou- pled to a Q-TOF instrument working in negative ion electrospray mode was proposed as the instrumental technique. Several polyphenols such as 3-caffeoylquinic acid, methyl 4-caffeoylquinate, kaempferol-acetyl-glycoside, quercetin 3-rutinoside, quercetin-acetyl- glycoside, kaempferol 3-O-glucoside, and quercetin 3-O-glucoside were identiﬁed. In another work, a Q-Orbitrap HRMS instrument was used to assess a comprehensive investi- gation of the polyphenolic constituents of fennel waste extract, showing that chlorogenic acids were the most abundant compounds [102]. Some applications based on MS instru- ments with an even higher resolution than an Orbitrap analyzer, such as Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), have also been described in the literature. For example, Maia et al. [104] evaluated Vitis vinifera “Pinot noir” leaves as a source of bioactive nutraceutical compounds using an FT-ICR-MS instrument, identify- ing the presence of numerous compounds that are known to possess diverse nutritional and pharmacological properties, such as caffeic acid, catechin, kaempferol and quercetin, several phytosterols, and fatty acids. The use of ambient mass spectrometry (AMS) techniques has also been described for nutraceutical characterization. AMS involves the direct analysis of compounds from sample surfaces, allowing a straightforward study of unconventional bulk samples, such as whole tablets, plant parts, or tissue sections. The analysis takes place at ambient pressure outside the MS instrument, which speeds up the sampling process and without any sample preparation (or minimal sample manipulation). For example, Giffen et al. described the use of direct analysis in real time (DART) for the rapid identiﬁcation of Salvia species by chemometric processing [105]. The authors analyzed plant leaves in their native form by DART-HRMS without any sample preparation step, obtaining a derived chemical ﬁngerprinting of both fresh and dried salvia material. The presence of essential oil biomarkers such as 3-carene, -pinene, -pinene, -thujone, -caryophyllene, camphor, and borneol was conﬁrmed. In another work, Riya et al. revealed the important nutraceutical properties of Mauritius fruit (Ananas comosus) against diabetes [106]. In this case, some active compounds identiﬁed in ethyl acetate and methanolic extracts of the fruit using DART-HRMS were sinapic acid, daucosterol, 2-methylpropanoate, 2,3-dimethyl-4- hydroxy-4(2H)-furanone, methyl 2-methylbutanoate, and triterpenoid ergosterol. Desorption electrospray ionization (DESI) is another AMS technique allowing the direct identiﬁcation and determination of bioactive substances deposited on surfaces and from thin biological tissue sections with minimal (or without) sample treatment. In this case, a charged spray of solvent droplets is directed toward the surface to desorb and ionize the analytes, which are directed to the MS inlet under vacuum conditions. The investigation of phytochemicals from thin-layer chromatography (TLC) imprints or direct plant tissues is well described in the literature. As an example, the chemical proﬁling and separation of bioactive secondary metabolites in maca (Lepidium peruvianum) by normal- and reversed-phase TLC coupled to DESI-HRMS was proposed by Perez et al. [107]. The authors reported for the ﬁrst time the identiﬁcation of six potential plant antibiotics, phytoanticipins, glycosylated ascorbigens, and dihydroascorbigens from Maca seeds. Matrix-assisted laser desorption ionization (MALDI)TOF-MS is another excellent technique for the deeper characterization of polyphenols, especially for dealing with polymeric compounds such as PACs [108], especially for the elucidation of intermolecular Appl. Sci. 2021, 11, 8276 12 of 16 link positions. The polyphenol proﬁling of chestnut pericarp, integument, and curing water extracts to qualify these food by-products as a source of bioactive antioxidant compounds for nutraceutical applications was also described by MALDI-TOF-MS [109]. This method allowed the identiﬁcation of condensed and hydrolyzable tannins such as procyanidins and prodelphinidins. 5. Conclusions Polyphenols, including phenolic acids, ﬂavonoids, and stilbenes, display great an- tioxidant activity that may help to combat free radicals resulting from oxidative stress. Other interesting properties such as anti-inﬂammatory, antineoplastic, antimicrobial, hy- polipidemic, estrogenic, or hepatoprotective activities have been described as well. The chemical evaluation of these compounds is essential to ensure the content of the desired active species. Regarding analytical methods, spectroscopic methods are suitable for the evaluation of the overall antioxidant capacity of nutraceuticals. Electrochemical methods have also demonstrated their great performance to assess the antioxidant properties of products. The simultaneous proﬁling of multiple analytes relies on separation techniques, among which liquid chromatography is the most recommended one. Polyphenols can be monitored by UV/vis, ﬂuorescence, and mass spectrometry, with the latter being especially suitable for sensitive and selective detection. The hyphenation of liquid chromatography with mass spectrometry is also the technique of choice for the identiﬁcation and structural elucidation of unknown phytochemicals with bioactive properties. Author Contributions: J.S. conceived and designed the publication and wrote the core of the docu- ment; O.V.-C., O.N., M.G. and S.S. contributed to the bibliographic search, analysis of the information, and writing of different sections of the paper. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by the “Agencia Estatal de Investigación”, grant number PID2020- 114401RB-C22. Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Acknowledgments: Not applicable. Conﬂicts of Interest: The authors declare no conﬂict of interest. References 1. Leri, M.; Scuto, M.; Ontario, M.L.; Calabrese, V.; Calabrese, E.J.; Bucciantini, M.; Stefani, M. Healthy effects of plant polyphenols molecular mechanisms. Int. J. Mol. Sci. 2020, 21, 1250. [CrossRef] 2. Tomé-Carneiro, J.; Visioli, F. Polyphenol-based nutraceuticals for the prevention and treatment of cardiovascular disease: Review of human evidence. Phytomedicine 2016, 23, 1145–1174. [CrossRef] 3. Abuajah, C.I.; Ogbonna, A.C.; Osuji, C.M. Functional components and medicinal properties of food: A review. J. Food Sci. Technol. 2015, 52, 2522–2529. [CrossRef] 4. Lucci, P.; Saurina, J.; Núñez, O. Trends in LC-MS and LC-HRMS analysis and characterization of polyphenols in food. Trends Anal. Chem. 2017, 88, 1–24. [CrossRef] 5. Saurina, J. Characterization of wines using compositional proﬁles and chemometrics. Trends Anal. Chem. 2010, 29, 234–245. [CrossRef] 6. Gülçin, I. Antioxidant activity of food constituents: An overview. Arch. Toxicol. 2012, 86, 345–391. [CrossRef] [PubMed] 7. Farhood, B.; Mortezaee, K.; Goradel, N.H.; Khanlarkhani, N.; Salehi, E.; Nashtaei, M.S.; Najaﬁ, M.; Sahebkar, A. Curcumin as an anti-inﬂammatory agent: Implications to radiotherapy and chemotherapy. J. Cell. Physiol. 2019, 234, 5728–5740. [CrossRef] 8. Tabrizi, R.; Vakili, S.; Akbari, M.; Mirhosseini, N.; Lankarani, K.B.; Rahimi, M.; Mobini, M.; Jafarnejad, S.; Vahedpoor, Z.; Asemi, Z. The effects of curcumin-containing supplements on biomarkers of inﬂammation and oxidative stress: A systematic review and meta-analysis of randomized controlled trials. Phyther. Res. 2019, 33, 253–262. [CrossRef] 9. Tao, W.; Zhang, Y.; Shen, X.; Cao, Y.; Shi, J.; Ye, X.; Chen, S. Rethinking the Mechanism of the Health Beneﬁts of Proanthocyanidins: Absorption, Metabolism, and Interaction with Gut Microbiota. Compr. Rev. Food Sci. Food Saf. 2019, 18, 971–985. [CrossRef] Appl. Sci. 2021, 11, 8276 13 of 16 10. Coman, V.; Vodnar, D.C. Hydroxycinnamic acids and human health: Recent advances. J. Sci. Food Agric. 2020, 100, 483–499. [CrossRef] 11. Quideau, S.; Defﬁeux, D.; Douat-Casassus, C.; Pouységu, L. Plant polyphenols: Chemical properties, biological activities, and synthesis. Angew. Chemie Int. Ed. 2011, 50, 586–621. [CrossRef] 12. Tsao, R. Chemistry and biochemistry of dietary polyphenols. Nutrients 2010, 2, 1231–1246. [CrossRef] [PubMed] 13. Di Lorenzo, C.; Colombo, F.; Biella, S.; Stockley, C.; Restani, P. Polyphenols and human health: The role of bioavailability. Nutrients 2021, 13, 273. [CrossRef] 14. Panche, A.N.; Diwan, A.D.; Chandra, S.R. Flavonoids: An overview. J. Nutr. Sci. 2016, 5, e47. [CrossRef] 15. Flamini, R.; Mattivi, F.; De Rosso, M.; Arapitsas, P.; Bavaresco, L. Advanced knowledge of three important classes of grape phenolics: Anthocyanins, stilbenes and ﬂavonols. Int. J. Mol. Sci. 2013, 14, 19651–19669. [CrossRef] [PubMed] 16. Kubina, R.; Iriti, M.; Kabala-Dzik, A. Anticancer potential of selected ﬂavonols: Fisetin, kaempferol, and quercetin on head and neck cancers. Nutrients 2021, 13, 845. [CrossRef] [PubMed] 17. Ulusoy, H.G.; Sanlier, N. A minireview of quercetin: From its metabolism to possible mechanisms of its biological activities. Crit. Rev. Food Sci. Nutr. 2020, 60, 3290–3303. [CrossRef] [PubMed] 18. Hostetler, G.L.; Ralston, R.A.; Schwartz, S.J. Flavones: Food Sources, Bioavailability, Metabolism and Bioactivity. Adv. Nutr. 2017, 8, 423–435. [CrossRef] 19. Singh, M.; Kaur, M.; Silakari, O. Flavones: An important scaffold for medicinal chemistry. Eur. J. Med. Chem. 2014, 84, 206–239. [CrossRef] [PubMed] 20. Ko, K. Isoﬂavones: Chemistry, Analysis, Functions and Effects on Health and Cancer. Asian Pac. J. Cancer Prev. 2014, 15, 7001–7010. [CrossRef] 21. Messina, M. Soy foods, isoﬂavones, and the health of postmenopausal women. Am. J. Clin. Nutr. 2014, 100, 423S–430S. [CrossRef] 22. Testai, L.; Calderone, V. Nutraceutical value of citrus ﬂavanones and their implications in cardiovascular disease. Nutrients 2017, 9, 502. [CrossRef] 23. Tsuda, T. Dietary anthocyanin-rich plants: Biochemical basis and recent progress in health beneﬁts studies. Mol. Nutr. Food Res. 2012, 56, 159–170. [CrossRef] 24. Singh, B.N.; Shankar, S.; Srivastava, R.K. Green tea catechin, epigallocatechin-3-gallate (EGCG): Mechanisms, perspectives and clinical applications. Biochem. Pharmacol. 2011, 82, 1807–1821. [CrossRef] 25. Martin, M.A.; Ramos, S. Impact of dietary ﬂavanols on microbiota, immunity andinﬂammation in metabolic diseases. Nutrients 2021, 13, 850. [CrossRef] 26. Sabaghi, M.; Hoseyni, S.Z.; Tavasoli, S.; Mozafari, M.R.; Katouzian, I. Strategies of conﬁning green tea catechin compounds in nano-biopolymeric matrices: A review. Colloids Surfaces B Biointerfaces 2021, 204, 111781. [CrossRef] [PubMed] 27. Rauf, A.; Imran, M.; Abu-Izneid, T.; Patel, S.; Pan, X.; Naz, S.; Sanches Silva, A.; Saeed, F.; Rasul Suleria, H.A. Proanthocyanidins: A comprehensive review. Biomed. Pharmacother. 2019, 116, 108999. [CrossRef] 28. Krueger, C.G.; Reed, J.D.; Feliciano, R.P.; Howell, A.B. Quantifying and characterizing proanthocyanidins in cranberries in relation to urinary tract health. Anal. Bioanal. Chem. 2013, 405, 4385–4395. [CrossRef] [PubMed] 29. Mallebrera, B.; Maietti, A.; Tedeschi, P.; Font, G.; Ruiz, M.J.; Brandolini, V. Antioxidant capacity of trans-resveratrol dietary supplements alone or combined with the mycotoxin beauvericin. Food Chem. Toxicol. 2017, 105, 315–318. [CrossRef] 30. Kotha, R.R.; Luthria, D.L. Curcumin: Biological, pharmaceutical, nutraceutical, and analytical aspects. Molecules 2019, 24, 2930. [CrossRef] [PubMed] 31. Zálešák, F.; Bon, D.J.Y.D.; Pospíšil, J. Lignans and Neolignans: Plant secondary metabolites as a reservoir of biologically active substances. Pharmacol. Res. 2019, 146, 104284. [CrossRef] 32. Vidal-Casanella, O.; Nuñez, O.; Saurina, J. Liquid chromatographic ﬁngerprints for the characterization of ﬂavanol-rich nutraceu- ticals based on 4-dimethylaminocinnamaldehyde precolumn derivatization. Sci. Pharm. 2021, 89, 18. [CrossRef] 33. Gudzinskaite, I.; Stackeviciene, E.; Liaudanskas, M.; Zymone, K.; Zvikas, V.; Viskelis, J.; Urbstaite, R.; Janulis, V. Variability in the qualitative and quantitative composition and content of phenolic compounds in the fruit of introduced American cranberry (Vaccinium macrocarpon Aiton). Plants 2020, 9, 1379. [CrossRef] [PubMed] 34. Zhao, S.; Liu, H.; Gu, L. American cranberries and health beneﬁts—An evolving story of 25 years. J. Sci. Food Agric. 2020, 100, 5111–5116. [CrossRef] 35. Côté, J.; Caillet, S.; Doyon, G.; Sylvain, J.F.; Lacroix, M. Analyzing cranberry bioactive compounds. Crit. Rev. Food Sci. Nutr. 2010, 50, 872–888. [CrossRef] 36. Blumberg, J.B.; Camesano, T.A.; Cassidy, A.; Kris-Etherton, P.; Howell, A.; Manach, C.; Ostertag, L.M.; Sies, H.; Skulas-Ray, A.; Vita, J.A. Cranberries and their bioactive constituents in human health. Adv. Nutr. 2013, 4, 618–632. [CrossRef] 37. Wang, S.; Moustaid-Moussa, N.; Chen, L.; Mo, H.; Shastri, A.; Su, R.; Bapat, P.; Kwun, I.S.; Shen, C.L. Novel insights of dietary polyphenols and obesity. J. Nutr. Biochem. 2014, 25, 1–18. [CrossRef] [PubMed] 38. Ríos-Hoyo, A.; Gutiérrez-Salmeán, G. New Dietary Supplements for Obesity: What We Currently Know. Curr. Obes. Rep. 2016, 5, 262–270. [CrossRef] [PubMed] 39. Tsuda, T. Recent progress in anti-obesity and anti-diabetes effect of berries. Antioxidants 2016, 5, 13. [CrossRef] [PubMed] 40. Georgiev, V.; Ananga, A.; Tsolova, V. Recent advances and uses of grape ﬂavonoids as nutraceuticals. Nutrients 2014, 6, 391–415. [CrossRef] [PubMed] Appl. Sci. 2021, 11, 8276 14 of 16 41. Xia, E.Q.; Deng, G.F.; Guo, Y.J.; Li, H. Bin Biological activities of polyphenols from grapes. Int. J. Mol. Sci. 2010, 11, 622–646. [CrossRef] 42. Pereira, C.; Barros, L.; Ferreira, I.C. Extraction, identiﬁcation, fractionation and isolation of phenolic compounds in plants with hepatoprotective effects. J. Sci. Food Agric. 2016, 96, 1068–1084. [CrossRef] [PubMed] 43. Gostin, A.I.; Waisundara, V.Y. Edible ﬂowers as functional food: A review on artichoke (Cynara cardunculus L.). Trends Food Sci. Technol. 2019, 86, 381–391. [CrossRef] 44. Singleton, V.L.; Orthofer, R.; Lamuela-Raventós, R.M. Analysis of total phenols and other oxidation substrates and antioxidants by means of folin-ciocalteu reagent. Methods Enzymol. 1999, 299, 152–178. [CrossRef] 45. Gulcin, I. Antioxidants and antioxidant methods: An updated overview. Arch. Toxicol. 2020, 94, 651–715. [CrossRef] [PubMed] 46. Brainina, K.; Stozhko, N.; Vidrevich, M. Antioxidants: Terminology, methods, and future considerations. Antioxidants 2019, 8, 297. [CrossRef] [PubMed] 47. Shahidi, F.; Zhong, Y. Measurement of antioxidant activity. J. Funct. Foods 2015, 18, 757–781. [CrossRef] 48. Alcalde, B.; Granados, M.; Saurina, J. Exploring the Antioxidant Features of Polyphenols by Spectroscopic and Electrochemical Methods. Antioxidants 2019, 8, 523. [CrossRef] 49. Pekal, ˛ A.; Pyrzynska, K. Evaluation of Aluminium Complexation Reaction for Flavonoid Content Assay. Food Anal. Methods 2014, 7, 1776–1782. [CrossRef] 50. Feliciano, R.P.; Shea, M.P.; Shanmuganayagam, D.; Krueger, C.G.; Howell, A.B.; Reed, J.D. Comparison of isolated cran- berry (Vaccinium macrocarpon Ait.) proanthocyanidins to catechin and procyanidins A2 and B2 for use as standards in the 4-(dimethylamino)cinnamaldehyde assay. J. Agric. Food Chem. 2012, 60, 4578–4585. [CrossRef] 51. Payne, M.J.; Hurst, W.J.; Stuart, D.A.; Ou, B.; Fan, E.; Ji, H.; Kou, Y. Determination of total procyanidins in selected chocolate and confectionery products using DMAC. J. AOAC Int. 2010, 93, 89–96. [CrossRef] 52. Wang, Y.; Singh, A.P.; Hurst, W.J.; Glinski, J.A.; Koo, H.; Vorsa, N. Inﬂuence of Degree-of-Polymerization and Linkage on the Quantiﬁcation of Proanthocyanidins using 4-Dimethylaminocinnamaldehyde (DMAC) Assay. J. Agric. Food Chem. 2016, 64, 2190–2199. [CrossRef] [PubMed] 53. Vidal-Casanella, O.; Nuñez, O.; Hernández-Cassou, S.; Saurina, J. Assessment of Experimental Factors Affecting the Sensitivity and Selectivity of the Spectrophotometric Estimation of Proanthocyanidins in Foods and Nutraceuticals. Food Anal. Methods 2021, 14, 485–495. [CrossRef] 54. Krueger, C.G.; Chesmore, N.; Chen, X.; Parker, J.; Khoo, C.; Marais, J.P.J.; Shanmuganayagam, D.; Crump, P.; Reed, J.D. Critical reevaluation of the 4-(dimethylamino)cinnamaldehyde assay: Cranberry proanthocyanidin standard is superior to procyanidin A2 dimer for accurate quantiﬁcation of proanthocyanidins in cranberry products. J. Funct. Foods 2016, 22, 13–19. [CrossRef] 55. Arribas, A.S.; Martinez-Fernandez, M.; Chicharro, M. The role of electroanalytical techniques in analysis of polyphenols in wine. TrAC Trends Anal. Chem. 2012, 34, 78–96. [CrossRef] 56. Petrovic, S.C. Correlation of perceived wine astringency to cyclic voltammetric response. Am. J. Enol. Vitic. 2009, 60, 373–378. 57. Makhotkina, O.; Kilmartin, P.A. The use of cyclic voltammetry for wine analysis: Determination of polyphenols and free sulfur dioxide. Anal. Chim. Acta 2010, 668, 155–165. [CrossRef] 58. David, I.G.; Buleandră, M.; Popa, D.E.; Bîzgan, A.-M.C.; Moldovan, Z.; Badea, I.-A.; Iorgulescu, E.E.; Tekiner, T.A.; Basaga, H. Voltammetric determination of polyphenolic content as rosmarinic acid equivalent in tea samples using pencil graphite electrodes. J. Food Sci. Technol. 2016, 53, 2589–2596. [CrossRef] 59. David, I.G.; Bizgan, A.-M.C.; Popa, D.E.; Buleandra, M.; Moldovan, Z.; Badea, I.A.; Tekiner, T.A.; Basaga, H.; Ciucu, A.A. Rapid determination of total polyphenolic content in tea samples based on caffeic acid voltammetric behaviour on a disposable graphite electrode. Food Chem. 2015, 173, 1059–1065. [CrossRef] 60. Oliveira-Neto, J.R.; Rezende, S.G.; de Fátima Reis, C.; Benjamin, S.R.; Rocha, M.L.; de Souza Gil, E. Electrochemical behavior and determination of major phenolic antioxidants in selected coffee samples. Food Chem. 2016, 190, 506–512. [CrossRef] 61. Memon, A.F.; Solangi, A.R.; Memon, S.Q.; Mallah, A.; Memon, N. Quantitative separation of hesperidin, chrysin, epicatechin, epigallocatechin gallate, and morin using ionic liquid as a buffer additive in capillary electrophoresis. Electrophoresis 2018, 39, 1606–1612. [CrossRef] 62. Arries, W.J.; Tredoux, A.G.J.; de Beer, D.; Joubert, E.; de Villiers, A. Evaluation of capillary electrophoresis for the analysis of rooibos and honeybush tea phenolics. Electrophoresis 2017, 38, 897–905. [CrossRef] [PubMed] 63. Dresler, S.; Bogucka-Kocka, A.; Kovácik, ˇ J.; Kubrak, T.; Strzemski, M.; Wójciak-Kosior, M.; Rysiak, A.; Sowa, I. Separation and determination of coumarins including furanocoumarins using micellar electrokinetic capillary chromatography. Talanta 2018, 187, 120–124. [CrossRef] 64. Navarro, M.; Núñez, O.; Saurina, J.; Hernández-Cassou, S.; Puignou, L. Characterization of fruit products by capillary zone electrophoresis and liquid chromatography using the compositional proﬁles of polyphenols: Application to authentication of natural extracts. J. Agric. Food Chem. 2014, 62, 1038–1046. [CrossRef] [PubMed] 65. Przybylska, A.; Gackowski, M.; Koba, M. Application of capillary electrophoresis to the analysis of bioactive compounds in herbal raw materials. Molecules 2021, 26, 2135. [CrossRef] 66. Ahmad, N.; Zuo, Y.; Lu, X.; Anwar, F.; Hameed, S. Characterization of free and conjugated phenolic compounds in fruits of selected wild plants. Food Chem. 2016, 190, 80–89. [CrossRef] Appl. Sci. 2021, 11, 8276 15 of 16 67. Osman, M.F.; Hassan, N.M.; Khatib, A.; Tolos, S.M. Antioxidant activities of Dialium indum L. Fruit and gas chromatography-mass spectrometry (GC-MS) of the active fractions. Antioxidants 2018, 7, 154. [CrossRef] [PubMed] 68. Park, C.H.; Morgan, A.M.A.; Park, B.B.; Lee, S.Y.; Lee, S.; Kim, J.K.; Park, S.U. Metabolic analysis of four cultivars of liriope platyphylla. Metabolites 2019, 9, 59. [CrossRef] 69. Ifeanacho, M.O.; Ikewuchi, C.C.; Ikewuchi, J.C. Investigation of the proﬁle of phenolic compounds in the leaves and stems of Pandiaka heudelotii using gas chromatography coupled with ﬂame ionization detector. Food Sci. Nutr. 2017, 5, 646–652. [CrossRef] [PubMed] 70. Annunziata, G.; Maisto, M.; Schisano, C.; Ciampaglia, R.; Narciso, V.; Tenore, G.C.; Novellino, E. Effects of grape pomace polyphenolic extract (Taurisolo ) in reducing tmao serum levels in humans: Preliminary results from a randomized, placebo- controlled, cross-over study. Nutrients 2019, 11, 139. [CrossRef] [PubMed] 71. López-Gutiérrez, N.; Romero-González, R.; Plaza-Bolaños, P.; Martínez Vidal, J.L.; Garrido Frenich, A. Identiﬁcation and quantiﬁcation of phytochemicals in nutraceutical products from green tea by UHPLC-Orbitrap-MS. Food Chem. 2015, 173, 607–618. [CrossRef] 72. López-Gutiérrez, N.; Romero-González, R.; Martínez Vidal, J.L.; Frenich, A.G. Determination of polyphenols in grape-based nutraceutical products using high resolution mass spectrometry. LWT Food Sci. Technol. 2016, 71, 249–259. [CrossRef] 73. Bakhytkyzy, I.; Nuñez, O.; Saurina, J. Size Exclusion Coupled to Reversed Phase Liquid Chromatography for the Characterization of Cranberry Products. Food Anal. Methods 2019, 12, 604–611. [CrossRef] 74. Parets, L.; Alechaga, É.; Núñez, O.; Saurina, J.; Hernández-Cassou, S.; Puignou, L. Ultrahigh pressure liquid chromatography- atmospheric pressure photoionization-tandem mass spectrometry for the determination of polyphenolic proﬁles in the charac- terization and classiﬁcation of cranberry-based pharmaceutical preparations and natural ext. Anal. Methods 2016, 8, 4363–4378. [CrossRef] 75. Vidal-Casanella, O.; Arias-Alpizar, K.; Nuñez, O.; Saurina, J. Hydrophilic interaction liquid chromatography to characterize nutraceuticals and food supplements based on ﬂavanols and related compounds. Separations 2021, 8, 17. [CrossRef] 76. Cacciola, F.; Rigano, F.; Dugo, P.; Mondello, L. Comprehensive two-dimensional liquid chromatography as a powerful tool for the analysis of food and food products. TrAC Trends Anal. Chem. 2020, 127, 115894. [CrossRef] 77. Cacciola, F.; Arena, K.; Mandolﬁno, F.; Donnarumma, D.; Dugo, P.; Mondello, L. Reversed phase versus hydrophilic interaction liquid chromatography as ﬁrst dimension of comprehensive two-dimensional liquid chromatography systems for the elucidation of the polyphenolic content of food and natural products. J. Chromatogr. A 2021, 1645, 462129. [CrossRef] [PubMed] 78. Arena, K.; Cacciola, F.; Mangraviti, D.; Zoccali, M.; Rigano, F.; Marino, N.; Dugo, P.; Mondello, L. Determination of the polyphenolic fraction of Pistacia vera L. kernel extracts by comprehensive two-dimensional liquid chromatography coupled to mass spectrometry detection. Anal. Bioanal. Chem. 2019, 411, 4819–4829. [CrossRef] 79. Sommella, E.; Ismail, O.H.; Pagano, F.; Pepe, G.; Ostacolo, C.; Mazzoccanti, G.; Russo, M.; Novellino, E.; Gasparrini, F.; Campiglia, P. Development of an improved online comprehensive hydrophilic interaction chromatography reversed-phase ultra-high-pressure liquid chromatography platform for complex multiclass polyphenolic sample analysis. J. Sep. Sci. 2017, 40, 2188–2197. [CrossRef] 80. Tamasi, G.; Pardini, A.; Bonechi, C.; Donati, A.; Pessina, F.; Marcolongo, P.; Gamberucci, A.; Leone, G.; Consumi, M.; Magnani, A.; et al. Characterization of nutraceutical components in tomato pulp, skin and locular gel. Eur. Food Res. Tech- nol. 2019, 245, 907–918. [CrossRef] 81. Simeoni, M.C.; Pellegrini, M.; Sergi, M.; Pittia, P.; Ricci, A.; Compagnone, D. Analysis of Polyphenols in the Lamiaceae Family by Matrix Solid-Phase Dispersion Extraction Followed by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry Determination. ACS Omega 2018, 3, 17610–17616. [CrossRef] 82. Núñez, N.; Vidal-Casanella, O.; Sentellas, S.; Saurina, J.; Núñez, O. Characterization, classiﬁcation and authentication of turmeric and curry samples by targeted LC-HRMS polyphenolic and curcuminoid proﬁling and chemometrics. Molecules 2020, 25, 2942. [CrossRef] [PubMed] 83. Lozano-Mena, G.; Sánchez-González, M.; Parra, A.; Juan, M.E.; Planas, J.M. Identiﬁcation of gut-derived metabolites of maslinic acid, a bioactive compound from Olea europaea L. Mol. Nutr. Food Res. 2016, 60, 2053–2064. [CrossRef] 84. Garzón, G.A.; Narváez-Cuenca, C.E.; Kopec, R.E.; Barry, A.M.; Riedl, K.M.; Schwartz, S.J. Determination of carotenoids, total phenolic content, and antioxidant activity of Arazá (Eugenia stipitata McVaugh), an amazonian fruit. J. Agric. Food Chem. 2012, 60, 4709–4717. [CrossRef] [PubMed] 85. Sut, S.; Zengin, G.; Maggi, F.; Malagoli, M.; Dall’Acqua, S. Triterpene acid and phenolics from ancient apples of Friuli Venezia Giulia as nutraceutical ingredients: LC-MS study and in vitro activities. Molecules 2019, 24, 1109. [CrossRef] 86. Sut, S.; Poloniato, G.; Malagoli, M.; Dall’acqua, S. Fragmentation of the main triterpene acids of apple by LC- APCI-MSn. J. Mass Spectrom. 2018, 53, 882–892. [CrossRef] [PubMed] 87. Arrizabalaga-Larrañaga, A.; Campmajó, G.; Saurina, J.; Núñez, O.; Santos, F.J.; Moyano, E. Determination of capsaicinoids and carotenoids for the characterization and geographical origin authentication of paprika by UHPLC–APCI–HRMS. LWT- Food Sci. Technol. 2021, 139, 110533. [CrossRef] 88. Giuffrida, D.; Pintea, A.; Dugo, P.; Torre, G.; Pop, R.M.; Mondello, L. Determination of carotenoids and their esters in fruits of sea buckthorn (Hippophae rhamnoides L.) by HPLC-DAD-APCI-MS. Phytochem. Anal. 2012, 23, 267–273. [CrossRef] Appl. Sci. 2021, 11, 8276 16 of 16 89. Bettaiah, A.; Prabhushankar, H.B. Screening of Novel Source for Genistein by Rapid and Sensitive UPLC-APCI-TOF Mass Spectrometry. Int. J. Food Sci. 2021, 2021, 5537917. [CrossRef] 90. Zhou, Y.; Xu, X.Y.; Gan, R.Y.; Zheng, J.; Li, Y.; Zhang, J.J.; Xu, D.P.; Li, H. Bin Optimization of ultrasound-assisted extraction of antioxidant polyphenols from the seed coats of red sword bean (Canavalia gladiate (Jacq.) DC.). Antioxidants 2019, 8, 200. [CrossRef] 91. Sut, S.; Boschiero, I.; Solana, M.; Malagoli, M.; Bertucco, A.; Dall’Acqua, S. Supercritical CO extraction of eruca sativa using cosolvents: Phytochemical composition by LC-MS analysis. Molecules 2018, 23, 3240. [CrossRef] [PubMed] 92. El Majdoub, Y.O.; Alibrando, F.; Cacciola, F.; Arena, K.; Pagnotta, E.; Matteo, R.; Micalizzi, G.; Dugo, L.; Dugo, P.; Mondello, L. Chemical Characterization of Three Accessions of Brassica juncea L. Extracts from Different Plant Tissues. Molecules 2020, 25, 5421. [CrossRef] 93. Nkuimi Wandjou, J.G.; Lancioni, L.; Barbalace, M.C.; Hrelia, S.; Papa, F.; Sagratini, G.; Vittori, S.; Dall’Acqua, S.; Caprioli, G.; Beghelli, D.; et al. Comprehensive characterization of phytochemicals and biological activities of the Italian ancient apple ‘Mela Rosa dei Monti Sibillini. Food Res. Int. 2020, 137, 109422. [CrossRef] [PubMed] 94. Nzekoue, F.K.; Angeloni, S.; Navarini, L.; Angeloni, C.; Freschi, M.; Hrelia, S.; Vitali, L.A.; Sagratini, G.; Vittori, S.; Caprioli, G. Coffee silverskin extracts: Quantiﬁcation of 30 bioactive compounds by a new HPLC-MS/MS method and evaluation of their antioxidant and antibacterial activities. Food Res. Int. 2020, 133, 109128. [CrossRef] [PubMed] 95. Amat-Ur-rasool, H.; Symes, F.; Tooth, D.; Schaffert, L.N.; Elmorsy, E.; Ahmed, M.; Hasnain, S.; Carter, W.G. Potential nutraceutical properties of leaves from several commonly cultivated plants. Biomolecules 2020, 10, 1556. [CrossRef] 96. Reddy, M.N.; Adnan, M.; Alreshidi, M.M.; Saeed, M.; Patel, M. Evaluation of Anticancer, Antibacterial and Antioxidant Properties of a Medicinally Treasured Fern Tectaria coadunata with its Phytoconstituents Analysis by HR-LCMS. Anticancer. Agents Med. Chem. 2020, 20, 1845–1856. [CrossRef] 97. Rocchetti, G.; Senizza, B.; Zengin, G.; Mahomodally, M.F.; Senkardes, I.; Lobine, D.; Lucini, L. Untargeted metabolomic proﬁling of three Crataegus species (hawthorn) and their in vitro biological activities. J. Sci. Food Agric. 2020, 100, 1998–2006. [CrossRef] [PubMed] 98. Arshad, A.; Ahemad, S.; Saleem, H.; Saleem, M.; Zengin, G.; Abdallah, H.H.; Tousif, M.I.; Ahemad, N.; Mahomoodally, M.F. RP-UHPLC-MS chemical proﬁling, biological and in silico docking studies to unravel the therapeutic potential of heliotropium crispum desf. As a novel source of neuroprotective bioactive compounds. Biomolecules 2021, 11, 53. [CrossRef] 99. Rouphael, Y.; Bernardi, J.; Cardarelli, M.; Bernardo, L.; Kane, D.; Colla, G.; Lucini, L. Phenolic Compounds and Sesquiterpene Lactones Proﬁle in Leaves of Nineteen Artichoke Cultivars. J. Agric. Food Chem. 2016, 64, 8540–8548. [CrossRef] 100. Lachowicz, S.; Oszmianski, ´ J. Proﬁle of Bioactive Compounds in the Morphological Parts of Wild Fallopia japonica (Houtt) and Fallopia sachalinensis (F. Schmidt) and Their Antioxidative Activity. Molecules 2019, 24, 1436. [CrossRef] 101. Pepe, G.; Salviati, E.; Rapa, S.F.; Ostacolo, C.; Cascioferro, S.; Manfra, M.; Autore, G.; Marzocco, S.; Campiglia, P. Citrus sinensis and vitis vinifera protect cardiomyocytes from doxorubicin-induced oxidative stress: Evaluation of onconutraceutical potential of vegetable smoothies. Antioxidants 2020, 9, 378. [CrossRef] [PubMed] 102. Castaldo, L.; Izzo, L.; De Pascale, S.; Narváez, A.; Rodriguez-Carrasco, Y.; Ritieni, A. Chemical composition, in vitro bioacces- sibility and antioxidant activity of polyphenolic compounds from nutraceutical fennel waste extract. Molecules 2021, 26, 1968. [CrossRef] [PubMed] 103. Song, L.; Zheng, J.; Zhang, L.; Yan, S.; Huang, W.; He, J. Phytochemical Proﬁling and Fingerprint Analysis of Chinese Jujube (Ziziphus jujuba Mill.) Leaves of 66 Cultivars from Xinjiang Province. Molecules 2019, 24, 4528. [CrossRef] [PubMed] 104. Maia, M.; Ferreira, A.E.N.; Laureano, G.; Marques, A.P.; Torres, V.M.; Silva, A.B.; Matos, A.R.; Cordeiro, C.; Figueiredo, A.; Silva, M.S. Vitis vinifera “Pinot noir” leaves as a source of bioactive nutraceutical compounds. Food Funct. 2019, 10, 3822–3827. [CrossRef] [PubMed] 105. Giffen, J.E.; Lesiak, A.D.; Dane, A.J.; Cody, R.B.; Musah, R.A. Rapid Species-level Identiﬁcation of Salvias by Chemometric Processing of Ambient Ionisation Mass Spectrometry-derived Chemical Proﬁles. Phytochem. Anal. 2017, 28, 16–26. [CrossRef] [PubMed] 106. Riya, M.P.; Antu, K.A.; Vinu, T.; Chandrakanth, K.C.; Anilkumar, K.S.; Raghu, K.G. An in vitro study reveals nutraceutical properties of Ananas comosus (L.) Merr. var. Mauritius fruit residue beneﬁcial to diabetes. J. Sci. Food Agric. 2014, 94, 943–950. [CrossRef] 107. Perez, C.J.; Conceição, R.S.; Ifa, D.R. Chemical proﬁling and separation of bioactive secondary metabolites in Maca (Lepidium peruvianum) by normal and reverse phase thin layer chromatography coupled to desorption electrospray ionization-mass spectrometry. J. Mass Spectrom. 2021, 56, 1–14. [CrossRef] 108. Monagas, M.; Quintanilla-López, J.E.; Gómez-Cordovés, C.; Bartolomé, B.; Lebrón-Aguilar, R. MALDI-TOF MS analysis of plant proanthocyanidins. J. Pharm. Biomed. Anal. 2010, 51, 358–372. [CrossRef] 109. Pinto, G.; De Pascale, S.; Aponte, M.; Scaloni, A.; Addeo, F.; Caira, S. Polyphenol proﬁling of chestnut pericarp, integument and curing water extracts to qualify these food by-products as a source of antioxidants. Molecules 2021, 26, 2335. [CrossRef]

Journal

Applied Sciences – Multidisciplinary Digital Publishing Institute

Published: Sep 7, 2021

Keywords: polyphenols; flavonoids; bioactive compounds; antioxidants; nutraceuticals; analytical methods

Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

Get 20M+ Full-Text Papers For Less Than $1.50/day. Start a 14-Day Trial for You or Your Team.

Learn More →

Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

References (109)

Abstract

Journal

Recommended Articles

There are no references for this article.

Our policy towards the use of cookies