New method to determine antioxidant activity of polyphenols

The capacity of polyphenolic compounds to reduce the beta-carotene-linoleic acid cooxidation enzymatically induced by soybean lipoxygenase was assayed to determine their comprehensive antioxidant ability. The inhibition of the coupled oxidation is a well-known spectrophotometric method for the antioxidant activity measurement. A modification of this method is proposed to reduce assay time and to gain simplicity. The antioxidant abilities of several polyphenols were determined, and quercetin and sinapic acid were most active. These results were compared to those obtained by the DPPH* procedure to evaluate the free radical scavenging contribution to the total protective action. The highest values of antiradical activity were found for ellagic and quercetin.     

Quince (Cydonia oblonga Miller) fruit (pulp, peel, and seed) and Jam: antioxidant activity

To study the antioxidant activity of quince fruit (pulp, peel, and seed) and jam, methanolic extracts were prepared. Each extract was fractionated into a phenolic fraction and an organic acid fraction and was analyzed by high-performance liquid chromatography (HPLC)/diode array detection and HPLC/UV, respectively. Antiradical activities of the extracts and fractions were evaluated by a microassay using 1,1'-diphenyl-2-picrylhydrazyl. The phenolic fraction always exhibited a stronger antioxidant activity than the whole methanolic extract. Organic acid extracts were always the weakest in terms of antiradical activity, which seems to indicate that the phenolic fraction gives a higher contribution for the antioxidant potential of quince fruit and jam. The evaluation of the antioxidant activity of methanolic extracts showed that peel extract was the one presenting the highest antioxidant capacity. The IC50 values of quince pulp, peel, and jam extracts were correlated with the caffeoylquinic acids total content. Among the phenolic fractions, the seed extract was the one that exhibited the strongest antioxidant activity. The IC50 values of quince pulp, peel, and jam phenolic extracts were strongly correlated with caffeoylquinic acids and phenolics total contents. For organic acid fractions, the peel extract was the one that had the strongest antiradical activity. The IC50 values of quince pulp, peel, and jam organic acid fractions were correlated with the ascorbic acid and citric acid contents.     

Phenolic constituents in the fruits of Cinnamomum zeylanicum and their antioxidant activity

Defatted cinnamon fruit powder was successively extracted with benzene ethyl acetate, acetone, MeOH, and water. The concentrated water extract contained the maximum amount of phenolics and showed the highest antioxidant activities. Hence, it was fractionated by Diaion HP-20SS, Diaion HP-20, and Sephadex LH-20 column chromatographies. It gave five purified compounds, the purities of which were analyzed by HPLC. Compounds 1-5 were identified as 3,4-dihydroxybenzoic acid (protocatechuic acid), epicatechin-(2beta-->O-7,4beta-->8)-epicatechin-(4beta-->8)-epicatechin (cinnamtannin B-1), 4-[2,3-dihydro-3-(hydroxymethyl)-5-(3-hydroxypropyl)-7-(methoxy)benzofuranyl]-2-methoxyphenyl beta-d-glucopyranoside (urolignoside), quercetin-3-O-(6-O-alpha-l-rhamnopyranosyl)-beta-d-glucopyranoside (rutin), and quercetin-3-O-alpha-l-rhamnopyranoside by using extensive spectral studies. The antioxidant activities of purified compounds were screened for their antioxidative potential using beta-carotene-linoleate and 1,1-diphenyl-2-picrylhydrazyl model systems. All of the compounds showed antioxidant and radical scavenging activities. This is the first report of the isolation and identification of nonvolatile constituents and as well as antioxidant activities from cinnamon fruits.     

Isolation and identification of sea buckthorn (Hippophae rhamnoides) phenolics with antioxidant activity and α-glucosidase inhibitory effect

This study was performed to evaluate the antioxidant and α-glucosidase inhibitory effects from the extract, fractions, and isolated compounds of sea buckthorn leaves. Six compounds, kaempferol-3-O-β-D-(6'-O-coumaryl) glycoside, 1-feruloyl-β-D-glucopyranoside, isorhamnetin-3-O-glucoside, quercetin 3-O-β-D-glucopyranoside, quercetin 3-O-β-D-glucopyranosyl-7-O-α-L-rhamnopyranoside, and isorhamnetin-3-O-rutinoside, were isolated from sea buckthorn leaf extracts. The butanol fraction (EC(50) = 1.81 μg/mL) along with quercetin 3-O-β-D-glucopyranoside (EC(50) = 1.86 μg/mL) had a higher DPPH radical-scavenging activity and showed stronger reducing power (OD(700) = 1.83 and 1.78, respectively). The butanol fraction (477 mg GAE/g) contained the highest amount of phenolic compounds and also the most powerful α-glucosidase inhibitory effect (86%) at 5 μg/mL. The results indicate that sea buckthorn leaf extracts could potentially be used for food additives and the development of useful natural compounds.     

Evaluation of the phenolic content in the aerial parts of different varieties of Cichorium intybus L

Fresh aerial parts of different chicory varieties: green chicory (c.v. "Catalogna"), two red chicory varieties ("radicchio rosso di Chioggia" and "radicchio rosso di Treviso"), and Witloof or Belgian endive were analyzed by HPLC/DAD/MS. The chromatographic fingerprint was diagnostic for each variety. A monocaffeoyl tartaric acid, chlorogenic acid, and chicoric acid were detected in all the varieties, while cyanidin 3-O-glucoside, delphinidin 3-O-(6' malonyl) glucoside, and cyanidin 3-O-(6' malonyl) glucoside were the main phenolic compounds in the red varieties. The flavonoidic compounds, quercetin 3-O-glucuronide and luteolin 7-O-glucuronide, were absent in the Witloof sample. The phenolic compounds from total leaves were the same as those obtained from only the colored parts; nevertheless, the total amount was remarkably lower with a decrease of up to 80% for Belgian endive. Chemical stability at high temperature was observed for the phenolic fraction from the green variety after decoction at 100 degrees C for 30 min.     

Antioxidant activities and phenolic composition of extracts from Greek oregano,Greek sage,and summer savory

Oregano vulgare L. ssp. hirtum (Greek oregano), Salvia fruticosa (Greek sage), and Satureja hortensis (summer savory) were examined as potential sources of phenolic antioxidant compounds. The antioxidant capacities (antiradical activity by DPPH* test, phosphatidylcholine liposome oxidation, Rancimat test) and total phenol content were determined in the ethanol and acetone extracts of the dried material obtained from the botanically characterized plants. The ground material was also tested by the Rancimat test for its effect on the stability of sunflower oil. The data indicated that ground material and both ethanol and acetone extracts had antioxidant activity. Chromatographic (TLC, RP-HPLC) and NMR procedures were employed to cross-validate the presence of antioxidants in ethanol and acetone extracts. The major component of all ethanol extracts was rosmarinic acid as determined by RP-HPLC and NMR. Chromatography indicated the presence of other phenolic antioxidants, mainly found in the acetone extracts. The presence of the flavones luteolin and apigenin and the flavonol quercetin was confirmed in the majority of the extracts by the use of a novel (1)H NMR procedure, which is based on the strongly deshielded OH protons in the region of 12-13 ppm without previous chromatographic separation. This deshielding may be attributed to the strong intramolecular six-membered ring hydrogen bond of the OH(5)...CO(4) moiety.     

Separation and HPLC-MS identification of phenolic antioxidants from agricultural residues: almond hulls and grape pomace

Almond hulls and grape pomace are residues abundantly generated by agricultural industries, which could be processed to obtain bioactive products. To this purpose, crude ethanol extracts from both agricultural byproducts were attained and subsequently fractionated in order to obtain an organic/water fraction (FOW). Extracts and fractions were analyzed for antioxidant power and their phenolic components tentatively identified by HPLC-MS. Chromatographic peaks of almond hull extracts showed the occurrence of hydroxybenzoic and cinnamic acid derivatives, with minor presence of flavan-3-ols (ECG, EGCG), whereas the FOW fraction offered the additional presence of epicatechin (EC) and glycosylated flavonols. In the composition for extracts of white and red grape pomace several of these compounds were also detected but basically consisted of glycosylated flavonols (quercetin, kaempferol). As a difference between both grape pomaces, myricetin glycosyde was found in that from the red variety, whereas flavan-3-ols (EC, afzelechin) were only identified in white pomace. When their FOW fractions were analyzed, gallic acid and some hydroxybenzoic acids were additionally detected. Antioxidant activity was assessed by DPPH and TBARS assays. Almond hulls showed inhibition percentages lower than 50% in both assays, while the inhibition percentage ranged from 80% to 90% in pomace extracts. Red grape pomace extract was the most efficient antioxidant, with an EC50 value of 0.91 g/L for TBARS and 0.20 g/L for DPPH. Even appearing as two quite different vegetal matrixes, the composition of phenolics in grape pomace and almond hulls is quite similar, the main difference being the major occurrence of flavonols in grape pomace. This fact could presumably explain the lower antiradical activity of hull extracts.     

Antimutagenic and antioxidant properties of phenolic fractions from Andean purple corn (Zea mays L.)

The antimutagenic and antioxidant properties of various phenolic fractions obtained from Andean purple corn were examined by the Ames test and the DPPH antiradical assay. An anthocyanin-rich water fraction (WF) and an ethyl acetate fraction (EAF) showed a dose-dependent antimutagenic behavior against the food mutagen Trp-P-1 with IC50 values of 321.7 +/- 21.36 and 95.2 +/- 10.95 microg of chlorogenic acid equiv/plate, respectively, indicating that EAF was a more potent antimutagen. The antioxidant activities for WF and EAF were 1.019 +/- 0.05 and 0.838 +/- 0.11 microg of Trolox equiv/mug of phenolics, respectively. Further fractionation of WF and EAF revealed an ethyl acetate subfraction, EA-IV, with high antimutagen potency that contained a quercetin derivative. The mechanism of antimutagenic action of the WF is predominantly a blocking effect on the S-9 Mix activation system of the mutagen, whereas for the EAF, it is a dual mechanism involving blocking of the S-9 Mix and a scavenging action on Trp-P-1 electrophiles.     

Changes in phytochemical and antioxidant activity of selected pepper cultivars (Capsicum species) as influenced by maturity

The effect of fruit maturation on changes in carotenoids, flavonoids, total soluble reducing equivalents, phenolic acids, ascorbic acid, and antioxidant activity (AOX) in different pepper types (Capsicum annuum, Capsicum frutescens, and Capsicum chinese) was determined. Generally, the concentration of these chemical constituents increased as the peppers reached maturity. Peppers contained high levels of L-ascorbic acid and carotenoids at maturity, contributing 124-338% of the RDA for vitamin C and 0.33-336 RE/100 g of provitamin A activity, respectively. Levels of phenolic acids, capxanthin, and zeaxanthin generally increased during maturation, whereas the level of lutein declined. Flavonoid concentrations varied greatly among the pepper types analyzed and were negatively correlated to AOX under the conditions of the beta-carotene-linoleic assay. Model systems were used to aid in understanding the relationship between flavonoids and AOX. Significant increases in AOX were observed in pepper juice models in response to increasing dilution factors and the presence of EDTA, indicating a pro-oxidant effect due to metal ions in the system. In vitro models demonstrated that increasing levels of flavonoids in combination with constant levels of caffeic and ascorbic acid gave a resultant AOX that was either additive of the two compounds or competitive in their ability to scavenge peroxyl radicals. The model systems were in good agreement with the chemical composition of the pepper cultivars and reflected the interactions affecting AOX. More research is needed to understand the complex interactions that occur among various antioxidants present in pepper extracts.     

Antioxidant and antiradical activities in extracts of hazelnut kernel (Corylus avellana L.) and hazelnut green leafy cover

Phenolic compounds in the aqueous systems were extracted, from hazelnut kernel (HK) and hazelnut green leafy cover (HGLC), with 80% (v/v) ethanol (HKe and HGLCe) or 80% (v/v) acetone (HKa and HGLCa). The extracts were examined for their phenolic and condensed tannin contents and phenolic acid profiles (free and esterified fractions) as well as antioxidant and antiradical activities by total antioxidant activity (TAA), antioxidant activity in a beta-carotene-linoleate model system, scavenging of DPPH (2,2-diphenyl-1-picrylhydrazyl) radical, and reducing power. Significant differences (p < 0.05) in the contents of total phenolics, condensed tannins, and TAA existed among the extracts that were examined. HGLCa extract had the highest content of total phenolics (201 mg of catechin equivalents/g of extract), condensed tannins (542 mg of catechin equivalents/g of extract), and TAA (1.29 mmol of Trolox equivalents/g of extract) followed by HGLCe, HKa, and HKe extracts, respectively. Five phenolic acids (gallic acid, caffeic acid, p-coumaric acid, ferulic acid, and sinapic acid) were tentatively identified and quantified, among which gallic acid was the most abundant in both free and esterified forms. The order of antioxidant activity in a beta-carotene-linoleate model system, the scavenging effect on DPPH radical, and the reducing power in all extracts were in the following order: HGLCa > HGLCe > HKa > HKe. These results suggest that both 80% ethanol and acetone are capable of extracting phenolics, but 80% acetone was a more effective solvent for the extraction process. HGLC exhibited stronger antioxidant and antiradical activities than HK itself in both extracts and could potentially be considered as an inexpensive source of natural antioxidants.     

Stoichiometric and kinetic studies of phenolic antioxidants from Andean purple corn and red-fleshed sweetpotato

Stoichiometric and kinetic values of phenolics against DPPH (2,2-diphenyl-1-picrylhydrazyl) were determined for Andean purple corn (Zea mays L.) and red sweetpotato (Ipomoea batatas). Both crops had higher antioxidant capacity and antiradical kinetics than blueberries and higher or similar anthocyanin and phenolic contents. The second-order rate constant (k(2)) was 1.56, 1.12, 0.57, and 0.26 (mg antiradical/mL)(-1) s(-1) for red sweetpotato, Trolox, purple corn, and blueberry, respectively. On the molar basis of active hydroxyl groups, k(2)' showed the same order as for k(2). Corn cob and sweetpotato endodermis contributed the most in phenolic compounds and antioxidant capacity. Both crops studied can be considered as excellent novel sources of natural antioxidants for the functional food and dietary supplement markets.     

Characterization and quantitation of antioxidant constituents of sweet pepper (Capsicum annuum L.)

Sweet peppers (Capsicum annuum L.) cv. Vergasa have been studied at four maturity stages (immature green, green, immature red, and red). The individual phenolics (hydroxycinnamic acids and flavonoids), vitamin C (ascorbic acid and dehydroascorbic acid), and individual carotenoids were characterized and quantified. Five hydroxycinnamic derivatives and 23 flavonoids were characterized and quantified from the pericarp of sweet pepper by high-performance liquid chromatography-diode array detection-electrospray ionization-mass spectrometry. Identification was carried out by their UV spectra, chromatographic comparisons with authentic markers, identification of hydrolysis products, and tandem mass spectrometry analysis. Hydroxycinnamic derivatives, O-glycosides of quercetin, luteolin, and chrysoeriol, and a large number of C-glycosyl flavones have been characterized. Some of these compounds were found for the first time in nature. Clear differences in the individual and total phenolic content were detected between the different maturity stages. Immature green pepper had a very high phenolic content while green, immature red, and red ripe peppers showed a 4-5-fold reduction. Ascorbic acid was the main form of vitamin C, and its content increased as the pepper reached maturity. The red ripe stage had a relevant impact on the carotenoids content. Thus, immature green peppers showed the highest content of polyphenols, while red ripe fruits had the highest content of vitamin C and provitamin A.     

Steam-blanched highbush blueberry (Vaccinium corymbosum L.) juice: phenolic profile and antioxidant capacity in relation to cultivar selection

High-quality standards in blueberry juice can be obtained only taking into account fruit compositional variability and its preservation along the processing chain. In this work, five highbush blueberry cultivars from the same environmental growing conditions were individually processed into juice after an initial blanching step and the influence was studied of the cultivar on juice phenolic content, distribution and relative antioxidant activity, measured as scavenging capacity on the artificial free-radical 2,2-diphenyl-1-picrylhydrazyl (DPPH*). A chromatographic protocol was developed to separate all main phenolic compounds in berries. A total of 15 glycosylated anthocyanins, catechin, galactoside, glucoside, and rhamnoside quercetin 3-derivatives, and main benzoic and cinnamic acids were identified. The total content and relative distribution in anthocyanins, chlorogenic acid, and quercetin of each juice were dependent upon cultivar, and the total content was highly correlated (rxy=0.97) to the antioxidant capacity. A selective protective effect of berry blanching in juice processing can be observed on more labile anthocyanin compounds.     

Vitamin C equivalent antioxidant capacity (VCEAC) of phenolic phytochemicals

To express the antioxidant capacity of plant foods in a more familiar and easily understood manner (equivalent to vitamin C mg/100 g), two stable radical species, ABTS(*)(-) and DPPH(*), commonly used for antioxidant activity measurements, were employed independently to evaluate their efficacies using apple polyphenolic extracts and seven polyphenolic standards including synthetic Trolox. Their antioxidant activities were expressed as vitamin C equivalent antioxidant capacity (VCEAC) in mg/100 g apple or mg/100 mL of the reference chemical compounds in 10 and 30 min using the ABTS(*)(-) and DPPH(*) scavenging assays, respectively. The antioxidant capacity of Gala apples and seven phenolic standards, determined by both ABTS(*)(-) and DPPH(*) scavenging assays, showed a dose-response of the first-order. Fresh Gala apples had a VCEAC of 205.4 +/- 5.6 mg/100 g using the ABTS assay, and the relative VCEACs of phenolic standards were as follows: gallic acid > quercetin > epicatechin > catechin > vitamin C > rutin > chlorogenic acid > Trolox. With the DPPH radical assay, the VCEAC of fresh Gala apples was 136.0 +/- 6.6 mg/100 g, and the relative VCEACs of seven phenolic standards were, in decreasing order, as follows: gallic acid > quercetin > epicatechin > catechin > or = vitamin C > Trolox > rutin > chlorogenic acid. Because the ABTS assay can be used in both organic and aqueous solvent systems, employs a specific absorbance at a wavelength remote from the visible region, and requires a short reaction time, it is a more desirable method than the DPPH assay. Therefore, it is recommended that antioxidant capacity be expressed as vitamin C mg/100 g equivalent (VCEAC) using the ABTS assay.     

Isolation and structural elucidation of two new glycosides from sage (Salvia officinalis L.)

Six compounds, 1-O-(2,3, 4-trihydroxy-3-methyl)butyl-6-O-feruloyl-beta-D-glucopyranoside, ethyl beta-D-glucopyranosyl tuberonate, p-hydroxybenzoic acid, (-)-hydroxyjasmonic acid, caffeic acid, and 4-hydroxyacetophenone 4-O-[5-O-(3, 5-dimethoxy-4-hydroxybenzoyl)-beta-D-apiofrunosyl]-(1-->2)-beta-D- glu copyranoside, were isolated from the n-butanol-soluble fraction of sage leaf extracts. Their structures were determined by spectral methods (MS, NMR, and 2D-NMR), and their antioxidant activities were measured. Among them, two new glycosides were elucidated. All of these compounds showed DPPH free radical scavenging activity at the concentration of 30 mM, and caffeic acid was the most active compound.     

Antioxidant activity, cytotoxicity, and DNA information of Glossogyne tenuifolia

This study investigates the antioxidant activity and cytotoxicity of Glossogyne tenuifolia extract on various cancer cell lines. The 5.8s DNA of G. tenuifolia was isolated, and the species of this plant was confirmed by NCBI's DNA database. G. tenuifolia was then extracted with ethanol and separated into several fractions using the partition procedure with water, n-butanol, and ethyl acetate (EA). Among these, the EA fraction most significantly affected the activity of DPPH(*) and superoxide anion scavenging. Additionally, only the EA fraction exhibited cytotoxicity on breast cancer cells (MCF-7 and MDA-MB-231) and liver cancer cells (Hep G2 and Hep 3B). Next, the EA fraction was further separated by column chromatography, and 15 fractions were obtained. Three effective components were isolated and identified separately from the active fractions: oleanolic acid (OA) from fraction 6, luteolin from fractions 8-10, and luteolin-7-glucoside from fraction 12. The test of these three compounds on scavenging activity of DPPH(*) and superoxide anion indicates that luteolin had the highest antioxidant activity, whereas the effect of OA was negligible. Additionally, a synergistic effect between luteolin and luteolin-7-glucoside was observed. Kick-out experiments showed that the activities were vanished or decreased. Especially on MDA-MB-231 and MCF-7 cells, the cytotoxicity completely disappeared when luteolin was eliminated from fractions 8-10. These findings demonstrate that luteolin plays a crucial role in the inhibition of the growth of hepatoma cancer cell lines. Fraction 3, which did not contain luteolin, luteolin-7-glucoside, and oleanolic acid, had cytotoxicity on MDA-MB-231, MCF-7, Hep G2, Hep 3B, and A549, which implies that this fraction contained some other effective ingredients and requires further study. The investigation is currently underway in our laboratory.     

Cellular antioxidant activity (CAA) assay for assessing antioxidants, foods, and dietary supplements

A cellular antioxidant activity (CAA) assay for quantifying the antioxidant activity of phytochemicals, food extracts, and dietary supplements has been developed. Dichlorofluorescin is a probe that is trapped within cells and is easily oxidized to fluorescent dichlorofluorescein (DCF). The method measures the ability of compounds to prevent the formation of DCF by 2,2'-azobis(2-amidinopropane) dihydrochloride (ABAP)-generated peroxyl radicals in human hepatocarcinoma HepG2 cells. The decrease in cellular fluorescence when compared to the control cells indicates the antioxidant capacity of the compounds. The antioxidant activities of selected phytochemicals and fruit extracts were evaluated using the CAA assay, and the results were expressed in micromoles of quercetin equivalents per 100 micromol of phytochemical or micromoles of quercetin equivalents per 100 g of fresh fruit. Quercetin had the highest CAA value, followed by kaempferol, epigallocatechin gallate (EGCG), myricetin, and luteolin among the pure compounds tested. Among the selected fruits tested, blueberry had the highest CAA value, followed by cranberry > apple = red grape > green grape. The CAA assay is a more biologically relevant method than the popular chemistry antioxidant activity assays because it accounts for some aspects of uptake, metabolism, and location of antioxidant compounds within cells.     

Functionality of bioactive compounds in Brazilian strawberry (Fragaria x ananassa Duch.) cultivars: evaluation of hyperglycemia and hypertension potential using in vitro models

Fruits of seven fully ripened strawberry cultivars grown in Brazil (Dover, Camp Dover, Camarosa, Sweet Charlie, Toyonoka, Oso Grande, and Piedade) were evaluated for total phenolics, antioxidant activity based on DPPH radical scavenging assay, and functionality such as inhibition of alpha-amylase, alpha-glucosidase, and angiotensin I-converting enzyme (ACE) relevant for potentially managing hyperglycemia and hypertension. The total phenolics content ranged from 966 to 1571 microg of gallic acid/g of fruit fresh weight for Toyonoka and Dover, respectively. No correlation was found between total phenolics and antioxidant activity. The major phenolic compounds in aqueous extracts of strawberries were ellagic acid, quercetin, and chlorogenic acid. Strawberries had high alpha-glucosidase inhibitory activity. However, alpha-amylase inhibitory activity was very low in all cultivars. This suggested that strawberries could be considered as a potential dietary source with anti-hyperglycemic potential. The evaluated cultivars had no significant ACE inhibitory activity, reflecting low anti-hypertensive potential.     

Changes in hydrophilic and lipophilic antioxidant activity in relation to their phenolic composition during the chamber drying of red grapes at a controlled temperature

The purpose of this work was to study the variation of phenol compounds, as measured by HPLC, during the chamber drying under controlled temperature conditions of red grapes of the Merlot and Tempranillo varieties in relation to antioxidant activity. Both lipophilic and hydrophilic antioxidant activities in these grapes increased during the drying process; the former was measured via proton transfer in the coupled oxidation reaction between linoleic acid and β-carotene, and the second via electron transfer in the DPPH assay. The hydrophilic component was invariably greater in Tempranillo grapes, and so was the lipophilic component in Merlot grapes. Only the increase in hydrophilic antioxidant activity obtained a significant correlation with the phenolic compounds during the drying process. However, based on the phenolic fraction analysis, this result was primarily due to phenolic polymers and, to a lesser extent, also to phenolic acids, flavans, and some flavonols and anthocyans.     

Isolation and Caenorhabditis elegans lifespan assay of flavonoids from onion

The main flavonoids were isolated from three selected onion cultivars. Three phenolic compounds were obtained by reverse-phase HPLC, and their structures were elucidated by multiple NMR measurements. There were two known compounds, quercetin and quercetin 3'-O-β-D-glucopyranoside (Q3'G), and one novel compound, quercetin 3-O-β-D-glucopyranoside-(4→1)-β-d-glucopyranoside (Q3M), which was identified in onion for the first time. These flavonoids were found to be more abundant in the onion peel than in the flesh or core. Their antioxidative activities were tested using the DPPH method, and their antiaging activities were evaluated using a Caenorhabditis elegans lifespan assay. No direct correlation was found between antioxidative activity and antiaging activity. Quercetin showed the highest antioxidative activity, whereas Q3M showed the strongest antiaging activity among these flavonoids, which might be related to its high hydrophilicity.