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1.
The antioxidant activity of oregano, parsley, olive mill wastewaters (OMWW), Trolox, and ethylenediaminetetraacetic acid (EDTA) was evaluated in bulk oils and oil-in-water (o/w) emulsions enriched with 5% tuna oil by monitoring the formation of hydroperoxides, hexanal, and t-t-2,4-heptadienal in samples stored at 37 degrees C for 14 days. In bulk oil, the order of antioxidant activity was, in decreasing order (p < 0.05), OMWW > oregano > parsley > EDTA > Trolox. The antioxidant activity in o/w emulsion followed the same order except that EDTA was as efficient an antioxidant as OMWW. In addition, the total phenolic content, the radical scavenging properties, the reducing capacity, and the iron chelating activity of OMWW, parsley, and oregano extracts were determined by the Folin-Ciocalteau, oxygen radical absorbance capacity, ferric reducing antioxidant power, and iron(II) chelating activity assays, respectively. The antioxidant activity of OMWW, parsley, and oregano in food systems was related to their total phenolic content and radical scavenging capacity but not to their ability to chelate iron in vitro. OMWW was identified as a promising source of antioxidants to retard lipid oxidation in fish oil-enriched food products.  相似文献   

2.
The contents of antioxidant nutritional compounds, total soluble phenolics (TSP), vitamin C, vitamin E, beta-carotene, and total carotenoids (TC), were correlated with the total antioxidant capacity (AOC) of hydrophilic (HPE) and lipophilic extracts (LPE) from eight horticultural crops, namely, guava, avocado, black sapote, mango, papaya, prickly pear fruit, cladodes, and strawberry. AOC was measured using six different assays: 2,2'-diphenyl-1-picrylhydrazyl (DPPH), N,N-dimethyl-p-phenylendiamine (DMPD), ferric-ion-reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), and total oxidant scavenging capacity (TOSC). AOC values from HPE were about 95 times higher than LPE values. HPE of guava had the highest AOC value when evaluated with DMPD, DPPH, FRAP, TEAC, and TOSC assays, whereas with ORAC assay, black sapote had the highest value. HPE of papaya and prickly pear fruit presented the lowest AOC values with all assays. From HPE, vitamin C and TSP contents were highly correlated with AOC for all assays, while from LPE, TC and beta-carotene contents possessed a high correlation with AOC only in the DMPD assay.  相似文献   

3.
The chemistry behind antioxidant capacity assays   总被引：3，自引：0，他引：3  
This review summarizes the multifaceted aspects of antioxidants and the basic kinetic models of inhibited autoxidation and analyzes the chemical principles of antioxidant capacity assays. Depending upon the reactions involved, these assays can roughly be classified into two types: assays based on hydrogen atom transfer (HAT) reactions and assays based on electron transfer (ET). The majority of HAT-based assays apply a competitive reaction scheme, in which antioxidant and substrate compete for thermally generated peroxyl radicals through the decomposition of azo compounds. These assays include inhibition of induced low-density lipoprotein autoxidation, oxygen radical absorbance capacity (ORAC), total radical trapping antioxidant parameter (TRAP), and crocin bleaching assays. ET-based assays measure the capacity of an antioxidant in the reduction of an oxidant, which changes color when reduced. The degree of color change is correlated with the sample's antioxidant concentrations. ET-based assays include the total phenols assay by Folin-Ciocalteu reagent (FCR), Trolox equivalence antioxidant capacity (TEAC), ferric ion reducing antioxidant power (FRAP), "total antioxidant potential" assay using a Cu(II) complex as an oxidant, and DPPH. In addition, other assays intended to measure a sample's scavenging capacity of biologically relevant oxidants such as singlet oxygen, superoxide anion, peroxynitrite, and hydroxyl radical are also summarized. On the basis of this analysis, it is suggested that the total phenols assay by FCR be used to quantify an antioxidant's reducing capacity and the ORAC assay to quantify peroxyl radical scavenging capacity. To comprehensively study different aspects of antioxidants, validated and specific assays are needed in addition to these two commonly accepted assays.  相似文献   

4.
Antioxidative activity of hydrolyzed protein prepared from alkali-solubilized catfish protein isolates was studied. The isolates were hydrolyzed to 5, 15, and 30% degree of hydrolysis using the protease enzyme, Protamex. Hydrolyzed protein was separated into hydrolysates and soluble supernatants, and both of these fractions were studied for their metal chelating ability, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), and their ability to inhibit the formation of thiobarbituric acid reactive substances (TBARS) in washed tilapia muscle containing tilapia hemolysate. Both hydrolysates and supernatants were characterized using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Results showed that DPPH radical scavenging ability and reducing power of catfish protein hydrolysates decreased, whereas the ORAC value, metal chelating ability, and ability to inhibit TBARS increased, with an increase in the degree of hydrolysis. Hydrolysate samples showed higher DPPH radical scavenging ability and Fe(3+) reducing ability, and supernatant samples had higher metal chelating ability. In general, low molecular weight (MW) peptides had high ORAC values and high metal chelating ability, and high MW peptides had a higher reducing power (FRAP) and were more effective in scavenging DPPH radicals. In a washed muscle model system, the ability of catfish protein hydrolysates and their corresponding supernatants to inhibit the formation of TBARS increased with an increase in the degree of hydrolysis.  相似文献   

5.
The antioxidant capacity (AOC) of three representative citrus limonoids, limonin, nomilin, and limonin glucoside, was examined by the oxygen radical absorbance capacity (ORAC), Trolox equivalent antioxidant capacity (TEAC), beta-carotene-linoleic acid bleaching, and 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging assays. Pure compounds and proper negative (cinnamic acid) and positive (2,6-di-tert-butyl-4-methylphenol (BHT) and ascorbic acid) controls were used to remove any ambiguity in interpreting results. In all cases, limonin and nomilin gave results equivalent to those of cinnamic acid, indicating that they do not possess any inherent AOC and should not be considered antioxidants. Similar results were observed for limonin glucoside, with the exception of an anomalous result obtained from the beta-carotene-linoleic acid bleaching assay. Limonin glucoside was deemed not to be an antioxidant on the basis of the three unequivocal assays.  相似文献   

6.
Swiss red wheat grain, bran, aleurone, and micronized aleurone were examined and compared for their free radical scavenging properties against 2,2-diphenyl-1-picrylhydrazyl radical (DPPH*), radical cation ABTS*+ and peroxide radical anion O(2)*-, oxygen radical absorbance capacity (ORAC), chelating capacity, total phenolic content (TPC), and phenolic acid composition. The results showed that micronized aleurone, aleurone, bran, and grain may significantly differ in their antioxidant properties, TPC, and phenolic acid composition. Micronized aleurone had the greatest antioxidant activities, TPC, and concentrations of all identified phenolic acids, suggesting the potential of postharvesting treatment on antioxidant activities and availability of TPC and phenolic acids. Ferulic acid was the predominant phenolic acid in Swiss red wheat and accounted for approximately 57-77% of total phenolic acids on a weight basis. Ferulic acid concentration was well correlated with scavenging activities against radical cation and superoxide anion, TPC, and other phenolic acid concentrations, suggesting the potential use of ferulic acid as a marker of wheat antioxidants. In addition, 50% acetone and ethanol were compared for their effects on wheat ORAC values. The ORAC value of 50% acetone extracts was 3-20-fold greater than that of the ethanol extracts, indicating that 50% acetone may be a better solvent system for monitoring antioxidant properties of wheat. These data suggest the possibility to improve the antioxidant release from wheat-based food ingredients through postharvesting treatment or processing.  相似文献   

7.
Phenolic profiles and antioxidant properties of a total of 30 soybean samples, including 27 grown in the North Dakota-Minnesota region and three soybeans from the other regions, were investigated. The total phenolic content (TPC), total flavonoids content (TFC), phenolic acids, flavonols, anthocyanins, and isoflavones were quantified. Antioxidant properties of soybean extracts were assessed using 2-diphenyl-1-picryhydrazyl free radical scavenging activity (DPPH), ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) methods. Results showed that black soybean cultivars possessed significantly higher TPC, TFC, DPPH, FRAP, and ORAC values than all yellow soybean cultivars. However, black soybean cultivars did not exhibit significantly higher individual phenolic contents (except for anthocyanins), such as phenolic acids and isoflavones, than the yellow soybean cultivars. The isoflavone profiles of North Dakota soybean cultivars were similar to those of South Dakota, but average values of total isoflavone (TI) contents were higher than soybeans grown in the other states and Korea and Japan according to the U.S. Department of Agriculture-Iowa State University Database on the isoflavone contents of foods. Correlation assays showed that TPC, TI, total phenolic acids, daidzin, genistin, malonyldaidzin, daidzein, genistein, and trans-cinnamic acid significantly ( r = 0.73, 0.62, 0.49, 0.68, 0.59, 0.59, 0.56, 0.47, and 0.76, respectively, p < 0.0001) correlated with ORAC values of yellow soybeans. Both isoflavones and phenolic acids contributed to the ORAC values of yellow soybeans. These data suggest that some selected soybean cultivars may be used as high-quality food-grade soybeans for providing high phenolic phytochemicals and antioxidant activities.  相似文献   

8.
为揭示日喀则青稞全籽粒所含酚类物质与抗氧化能力间的关系,遴选出抗氧化品质优异的品种,对13份青稞材料的酚类物质含量和抗氧化能力进行了品种间的多重比较分析、酚类物质含量和抗氧化能力的相关分析、抗氧化品质的主成分分析以及品种间的聚类分析。结果表明,按籽粒颜色可将13份青稞品种划分为棕、紫、黑三色,深色(紫色和黑色)品种中花色苷、原花青素、总黄酮和总酚含量较高,且氧化自由基吸收能力(ORAC)、铁离子还原能力(FRAP)、1,1-二苯基-2-三硝基苯肼(DPPH)自由基清除能力也高于浅色(棕色)品种。ORAC、FRAP、DPPH自由基清除能力与酚类物质含量之间存在显著或极显著相关性,而金属离子螯合能力(MCC)与酚类物质无显著相关性。主成分分析和聚类分析结果表明,可通过籽粒颜色来进行青稞抗氧化品质初筛,深色青稞品种尤其是黑色青稞品种籽粒抗氧化品质最高。研究青稞籽粒酚类物质抗氧化有助于完善青稞抗氧化品质评价体系,为开发青稞抗氧化功能食品筛选出抗氧化能力优异的品种。  相似文献   

9.
An electron spin resonance (ESR) spectrometry study was conducted to examine the free radical scavenging properties of bran extracts of Alliance and Wichita wheat using hydroxyl radical (HO*), 2,2-diphenyl-1-picryhydrazyl radical (DPPH*), and superoxide radical anion (O2*-) and their chelating capacities against Cu2+. Also reported is the radical cation 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS*+) scavenging activity, oxygen radical absorbing capacity (ORAC), and chelating property against Fe2+ of the bran extracts measured by the spectrophotometric methods. Significant radical scavenging and chelating capacities were detected in the bran extracts, along with significant levels of phenolic acids, tocopherols, and carotenoids. Ferulic acid, with a concentration range of 130.60-146.38 microg/g, was the predominant phenolic acid in all of the tested bran samples and accounted for approximately 53-67% of total phenolic acids on a weight basis. Total tocopherol concentration ranged from 1.87 to 2.95 micromol/100 g of bran, whereas total carotenoid level was 0.20-0.33 micromol/100 g of bran. In addition, both wheat variety and growing conditions might significantly alter antioxidant properties and concentrations of beneficial components in wheat bran.  相似文献   

10.
Various extracts of the aerial parts of Barkleyanthus salicifolius (Asteraceae) and Penstemon gentianoides (Scrophulariaceae) have been used in folk medicine to treat many ailments, particularly inflammation and migraine. Neither the bioactive components responsible nor the mechanisms involved have been evaluated. Here are reported antioxidant activities of their methanol, dichloromethane, and ethyl acetate extracts. Samples were evaluated for oxygen radical absorption capacity (ORAC), ferric reducing antioxidant power (FRAP), 2,2-diphenyl-1-picryl-hydrazyl (DPPH) radical scavenging, and inhibition of the formation of thiobarbituric acid reactive species (TBARS), a measure of lipid peroxidation. Antioxidant activities were strongly correlated with total polyphenol content. The most active extracts from P. gentianoides in scavenging DPPH radicals and inhibiting TBARS formation were the methanol extract (A) and a further ethyl acetate extract of this (E). Partition E was further divided into eight fractions, and both E and the fractions were compared for activity against butylated hydroxytoluene, quercetin, and tocopherol. Partition E and the most active fractions, 5 and 6, were found to have I(50) values of 14.1, 38.6, and 41.8 ppm, respectively, against DPPH and 18.5, 26.0, and 12.7 ppm, respectively, against TBARS formation. Consistent with this finding, partition E and fractions 4-6 had the greatest ORAC and FRAP values. These results show that these plants could be useful antioxidant sources.  相似文献   

11.
A total of 927 freeze-dried vegetable samples, including 111 white cabbages, 59 carrots, 51 snap beans, 57 cauliflower, 33 white onions, 48 purple onions, 130 broccoli, 169 tomatoes, 25 beets, 88 peas, 88 spinach, 18 red peppers, and 50 green peppers, were analyzed using the oxygen radical absorption capacity (ORAC) and ferric reducing antioxidant capacity (FRAP) methods. The data show that the ORAC and FRAP values of vegetable are not only dependent on species, but also highly dependent on geographical origin and harvest time. The two antioxidant assay methods, ORAC and FRAP, also give different antioxidant activity trends. The discrepancy is extensively discussed based on the chemistry principles upon which these methods are built, and it is concluded that the ORAC method is chemically more relevant to chain-breaking antioxidants activity, while the FRAP has some drawbacks such as interference, reaction kinetics, and quantitation methods. On the basis of the ORAC results, green pepper, spinach, purple onion, broccoli, beet, and cauliflower are the leading sources of antioxidant activities against the peroxyl radicals.  相似文献   

12.
Defatted peanut meal hydrolysate (DPMH) was purified using ultrafiltration, gel filtration chromatography, and high-performance liquid chromatography. A tripeptide with strong oxygen radical absorbance capacity (ORAC) was isolated and identified as Tyr-Gly-Ser by ESI-MS/MS. It was then synthesized to measure its antioxidant properties in different systems. The ORAC value of Tyr-Gly-Ser was 3-fold higher than that of glutathione (GSH), and it displayed a stronger protective effect on linoleic acid peroxidation and H(2)O(2)-induced oxidative injury in rat pheochromocytoma line PC12 cells than GSH (p < 0.05). However, Tyr-Gly-Ser showed negligible DPPH radical scavenging activity, reducing power, and no metal chelating ability. The results suggested that Tyr-Gly-Ser displayed antioxidant activity via the hydrogen atom transfer mechanism, and the Tyr at the N-terminal was the hydrogen donor. The ORAC assay was recommended as a reliable and effective method to measure the antioxidant activity in the course of antioxidant peptide isolation.  相似文献   

13.
Antioxidant capacity of hydrophilic and lipophilic extracts from eight broccoli genotypes was compared using the oxygen radical absorbance capacity (ORAC) assay. Each genotype was analyzed for carotenoid, tocopherol, ascorbic acid, and flavonoid content. Results indicate that the antioxidant capacity of hydrophilic extracts ranged from 65.8 to 121.6 micromol trolox equivalents (TE)/g of tissue, and the capacity of lipophilic extracts ranged from 3.9 to 17.5 micromol TE/g. Ascorbic acid and flavonoid content of the hydrophilic extracts did not explain the total variation in antioxidant capacity of those extracts, suggesting either the presence of other antioxidant components that have yet to be identified or that the known antioxidants are producing synergistic effects. The carotenoids did correlate with antioxidant capacity of the lipophilic extracts and accounted for the majority of the variability in that fraction. The variability in hydrophilic and lipophilic antioxidant capacity found among these genotypes suggests that potential efficacy from antioxidants will vary considerably from genotype to genotype.  相似文献   

14.
The isolation and identification of a phytocomplex from olive mill waste waters (OMWW) was achieved. The isolated phytocomplex is made up of the following three phenolic compounds: hydroxytyrosol (3,4-DHPEA), tyrosol (p-HPEA) and the dialdehydic form of decarboxymethyl elenolic acid, linked with (3,4-dihydroxyphenyl)ethanol (3,4-DHPEA-EDA). The purification of this phytocomplex was reached by partial dehydration of the OMWW, followed by liquid-liquid extraction with ethyl acetate and middle pressure liquid chromatography (MPLC) on a Sephadex LH-20 column. The phytocomplex accounted for 6% of the total phenolic content of the OMWW. The phytocomplex and individual compounds were tested for antioxidant capacity by the oxygen radical absorbance capacity (ORAC) method. The ORAC phytocomplex produced 10,000 ORAC units/g dry weight, whereas the cellular antioxidant activity, measured by the cellular antioxidant activity in red blood cell (CAA-RBC) method, demonstrated that the phytocomplex and all of the components are able to permeate the cell membrane thus exhibiting antioxidant activity inside the red blood cells. Our phytocomplex could be employed in the formulation of fortified foods and nutraceuticals, with the goal to obtain substantial health protective effects due to the suitable combination of the component molecules.  相似文献   

15.
Four kinds of solvent extracts from three Chinese barley varieties (Ken-3, KA4B, and Gan-3) were used to examine the effects of extraction solvent mixtures on antioxidant activity evaluation and their extraction capacity and selectivity for free phenolic compounds in barley through free radical scavenging activity, reducing power and metal chelating activity, and individual and total phenolic contents. Results showed that extraction solvent mixtures had significant impacts on antioxidant activity estimation, as well as different extraction capacity and selectivity for free phenolic compounds in barley. The highest DPPH* and ABTS*+ scavenging activities and reducing power were found in 80% acetone extracts, whereas the strongest *OH scavenging activity, O2*- scavenging activity, and metal chelating activity were found in 80% ethanol, 80% methanol, and water extracts, respectively. Additionally, 80% acetone showed the highest extraction capacity for (+)-catechin and ferulic, caffeic, vanillic, and p-coumaric acids, 80% methanol for (-)-epicatechin and syringic acid, and water for protocatechuic and gallic acids. Furthermore, correlations analysis revealed that TPC, reducing power, DPPH* and ABTS*+ scavenging activities were well positively correlated with each other (p < 0.01). Thus, for routine screening of barley varieties with higher antioxidant activity, 80% acetone was recommended to extract free phenolic compounds from barley. DPPH* scavenging activity and ABTS*+ scavenging activity or reducing power could be used to assess barley antioxidant activity.  相似文献   

16.
Methods are described for the extraction and analysis of hydrophilic and lipophilic antioxidants, using modifications of the oxygen radical absorbing capacity (ORAC(FL)) procedure. These methods provide, for the first time, the ability to obtain a measure of "total antioxidant capacity" in the protein free plasma, using the same peroxyl radical generator for both lipophilic and hydrophilic antioxidants. Separation of the lipophilic and hydrophilic antioxidant fractions from plasma was accomplished by extracting with hexane after adding water and ethanol to the plasma (hexane/plasma/ethanol/water, 4:1:2:1, v/v). Lipophilic and hydrophilic antioxidants were efficiently partitioned between hexane and aqueous solvents. Conditions for controlling temperature effects and decreasing assay variability using fluorescein as the fluorescent probe were validated in different laboratories. Incubation (37 degrees C for at least 30 min) of the buffer to which AAPH was dissolved was critical in decreasing assay variability. Lipophilic antioxidants represented 33.1 +/- 1.5 and 38.2 +/- 1.9% of the total antioxidant capacity of the protein free plasma in two independent studies of 6 and 10 subjects, respectively. Methods are described for application of the assay techniques to other types of biological and food samples.  相似文献   

17.
Black soybeans have been used as an excellent dietary source for disease prevention and health promotion in China for hundreds of years. However, information about the distribution of health-promoting phenolic compositions in different physical parts of black soybean and the contribution of phenolic compositions to overall antioxidant capacity is limited. To elucidate the distribution of phenolic composition and their contribution to antioxidant activities in black soybean, the total and individual phenolic profiles, and antioxidant capacities of seed coat, dehulled and whole black soybean were systematically investigated. The seed coat exhibited much higher total phenolic indexes and antioxidant activities than whole and dehulled black soybean. Dehulled black soybean possessed similar levels of total phenolic content, total flavonoid content, 2-diphenyl-1-picryhydrazyl (DPPH) radical scavenging activity, ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC) activities as compared to whole yellow soybean. Cyanidin-3-glucoside, petunidin-3-glucoside, and peonidin-3-glucoside were detected in the seed coat but not in dehulled black soybean and yellow soybean. Among benzoic acid detected, caffeic and chlorogenic acid were the predominant phenolic acids. Whole black soybean and dehulled black soybean exhibited similar isoflavone contents in 7- O-beta-glucosides and malonylglucosides of daidzein and genistein. The seed coat possessed significantly ( p < 0.05) lower 7- O-beta-glucosides and malonylglucosides of daidzein and genistein, acetylglycitin, and total isoflavones than whole and dehulled black soybean. The contribution of phenolics in the seed coat to the antioxidant activity of black soybean parts depends on the assay methods. When measured with the DPPH and FRAP methods, the seed coat contributed 90% of the total antioxidant capacity of black soybean. However, when measured with the ORAC method, the seed coat and dehulled portion contributed approximately equally the total antioxidant capacity of black soybeans. The information generated from this study on the distribution and content of their active components is useful for the effective use of black soybeans as an ingredient for promoting health.  相似文献   

18.
A novel fluorometric method was developed and validated for hydroxyl radical scavenging capacity (HOSC) estimation using fluorescein as the probe. A constant flux of pure hydroxyl radical is generated under physiological pH using a Fenton-like Fe3+/H2O2 reaction. The generation of pure hydroxyl radicals under the experimental conditions was evaluated and confirmed using electron spin resonance with DMPO spin-trapping measurements. The hydroxyl radical scavenging capacity of a selected antioxidant sample is quantified by measuring the area under the fluorescence decay curve with or without the presence of the antioxidant and expressed as Trolox equivalents per unit of the antioxidant. The assay may be performed using a plate reader with a fluorescence detector for high-throughput measurements. The assay was validated for linearity, precision, accuracy, reproducibility, and its correlation with a popular peroxyl radical scavenging capacity assay using selected pure antioxidant compounds and botanical extracts. This method may provide researchers in the food, nutrition, and medical fields an easy to use protocol to evaluate free radical scavenging capacity of pure antioxidants and natural extracts in vitro against the very reactive hydroxyl radical, which may be linked to numerous degenerative diseases and conditions.  相似文献   

19.
Two barley varieties (Falcon and AC Metcalfe) were separated by pearling into seven fractions and subsequently extracted with 80% methanol. The extracts, after solvent removal, were evaluated for their radical scavenging efficacy using Trolox equivalent antioxidant capacity (TEAC). The radical scavenging capacity of the extracts was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, oxygen radical absorbance capacity (ORAC(FL)), and superoxide radical assays and a photoinduced chemiluminescence technique. In both barley varieties the outermost fraction (F1) yielded the highest phenolic content. In general, Falcon had a significantly higher total phenolic content than AC Metcalfe. A similar trend was observed for TEAC, DPPH, and superoxide radical scavenging capacities of the extracts. The contents of water-soluble antioxidants of Falcon and AC Metcalfe were 1.15-12.98 and 2.20-12.25 micromol of Trolox equiv/(g of defatted material), while the corresponding lipid-soluble counterparts varied from 1.44 to 4.70 micromol of alpha-tocopherol equiv/(g of defatted material). Phenolic acids, namely, vanillic, caffeic, p-coumaric, ferulic, and sinapic acids, were identified by HPLC in barley fractions.  相似文献   

20.
This paper reports a simple, rapid, and sensitive assay for assessing peroxyl radical scavenging capacity (PSC) of both hydrophilic and lipophilic antioxidant compounds and food extracts. The assay is based on the degree of inhibition of dichlorofluorescin oxidation by antioxidants that scavenge peroxyl radicals, generated from thermal degradation of 2,2'-azobis(amidinopropane). For hydrophilic antioxidant activity, the dose required to cause a 50% inhibition of the reaction (EC(50)) ranged from 2.41 +/- 0.02 (EGCG) to 21.26 +/- 0.38 microM (ferulic acid). EC(50) values for the hydrophilic antioxidant activity of food extracts ranged from 309.2 +/- 3.63 (apple) to 3345.1 +/- 151.5 micromol of vitamin C equiv/100 g for wheat bran. The EC(50) values for lipophilic antioxidant activity were 1.58 +/- 0.11 (Trolox), 4.35 +/- 0.43 (alpha-tocopherol), 18.94 +/- 0.38 (BHA), and 182.69 +/- 13.7 microM (BHT). Whole grain lipophilic antioxidant activity ranged from 3.49 +/- 0.57 (wheat) to 8.79 +/- 1.98 micromol of alpha-tocopherol equiv/100 g of rice. Hydrophilic antioxidant activity contributed >98% of the total antioxidant activity (hydrophilic plus lipophilic) of whole grains tested. The PSC assay was accurate (86-108% recovery), precise (0.12-11% CV), and reproducible (12% RSD) and produced results comparable to those of similar published assays. The PSC assay can be routinely used to analyze or screen both hydrophilic and lipophilic antioxidants or food extracts and will be a valuable alternative biomarker for future epidemiological studies of chronic diseases.  相似文献   

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