Antioxidant potential of two red seaweeds from the Brazilian coasts

In this work, in vitro antioxidant activity of two Brazilian red seaweeds, Gracilaria birdiae and Gracilaria cornea, was characterized. The total phenolic content, the radical-scavenging activity and the antioxidant activity were determined in two solvent extracts of the algae. Liquid chromatography-mass spectrometry (LC-MS/MS) allowed identification of important antioxidant compounds. The ethanol extract of G. birdiae was found to have the highest value of total phenolic content: 1.13 mg of gallic acid equiv (GAE)/g of extract. The radical-scavenging activity of G. birdiae and G. cornea extracts has been evaluated at different extract concentrations; the IC(50) values of ethanolic extracts of G. cornea and G. birdiae were 0.77 and 0.76 mg mL(-1), respectively, while for methanolic extracts, the IC(50) values of G. cornea and G. birdiae were 0.86 and 0.76 mg mL(-1), respectively. The antioxidant activities of these two seaweeds' extracts as assessed by the β-carotene-linoleic acid assay were equally high, achieving values of β-carotene oxidation inhibition of up to 40%. Finally, in the methanolic extracts, LC-MS/MS allowed identification in both algae of two important antioxidants: apigenin and gallic acid.     

Isolation of antioxidant compounds from the methanolic extract of the roots of Decalepis hamiltonii (Wight and Arn.)

The tuberous roots of Decalepis hamiltonii are consumed as pickles and beverages and are believed to possess health-promoting properties. We have investigated the antioxidant potential of the roots. The methanolic extract of the root showed a high antioxidant activity. The methanolic extract was fractionated on a silica gel column, which showed three major fractions with good antioxidant activity. The active fractions were further subjected to preparative thin layer and silica gel column chromatography, which yielded six pure compounds. The purified compounds were characterized by MS, 1H NMR, 13C NMR, and two-dimensional NMR spectroscopic techniques and identified as 2-hydroxy-4-methoxybenzaldehyde, p-anisaldehyde, vanillin, borneol, salicylaldehyde, and bis-2,3,4,6-galloyl-alpha/beta-D-glucopyranoside. The latter compound, named decalepin, is a new antioxidant molecule from the plant kingdom. The purified compounds showed antioxidant activities in in vitro assays such as inhibition of lipid peroxidation, hydroxyl radical, superoxide anion, and 1,1-diphenyl-2picrylhydrazyl radical scavenging. This is the first report of the antioxidant constituents of the roots of Decalepis hamiltonii.     

Phenolic constituents and antioxidant properties of Xanthosoma violaceum leaves

An extract of Xanthosoma violaceum leaves was subjected to a polyphenol profile determination, including total polyphenols, and antioxidant activity evaluation. Analysis of the extract resulted in the isolation of a new flavone C-glycoside, apigenin 6-C-beta-D-glucopyranosyl-8-C-beta-D-apiofuranoside (1), as well as known flavone C-glycosides, including vitexin (2), isovitexin (3), isovitexin 4'-O-rhamnopyranoside (4), apigenin 6-C-[beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside] (5), and apigenin 6,8-diC-beta-D-glucopyranoside (6). The antioxidant activity of the extract was assessed by means of two different in vitro tests: bleaching of the stable 1,1-diphenyl-2-picrylhydrazyl radical (DPPH test) and peroxidation induced by the water-soluble radical initiator 2,2'-azobis(2-amidinopropane) hydrochloride, on mixed dipalmitoylphosphatidylcholine/linoleic acid unilamellar vesicles (LP-LUV test). In both tests used, the extract and a fraction II showed a significant antioxidant/free-radical scavenging effect (fraction II, EC(50) = 11.6 microg/mL) in comparison to alpha-tocopherol (EC(50) = 10.1 microg/mL).     

Antioxidant activity of indigenous edible mushrooms

The current study was undertaken to measure the antioxidant potential from water and methanolic extracts of fruiting bodies of 23 species of mushrooms naturally grown in different geographic locations of India. The antioxidant ability of each species was analyzed for the total antioxidative status, employing multimechanistic antioxidative assays such as inhibition of lipid peroxidation, determination of reducing power, and free radical scavenging ability, in addition to determination of total phenolics and identification of phenolic acids by HPLC analysis, because the phenolics are known to contribute largely to antioxidant potential. The antioxidant potential of these varieties of mushrooms was determined by summing the antioxidative activity (AOA) of each variety by varied antioxidant assays followed by determining the relative percent of AOA defined as the "antioxidant index" (AI). On the basis of the AI, the mushroom species were graded as very high, high, moderate, and low. Termitomyces heimii was identified as the best variety, which showed 100% AI with 37 mg of phenolics/g of sample, 418 units of reducing power ability (RPA)/g, and an IC50 of approximately 1.1 mg (dry weight)/mL, free radical scavenging activity (FRS) in the water extract followed by 11.2 mg of phenolics/g, 275 units of RPA/g, and an IC50 of approximately 2.7 mg (dry weight)/mL of FRS in the methanolic extract. Following T. heimii, Termitomyces mummiformis exhibited an AI of 86% within the "very high" group. Potent inhibitions of lipid peroxidation of approximately 100 and 69% was also observed in T. heimii and T. mummiformis, respectively. Water extracts ranged from 34 to 49% and methanolic extracts varied from 20 to 32% on dry weight of mushroom fruiting body. Total phenolic compounds were higher in the water extracts (2-37 mg/g) than in methanolic extract (0.7-11.2 mg/g). The AOA measured in the water extract was better than that from the methanolic extract. HPLC analysis of phenolic acids in the two mushroom species, namely, T. heimii and T. mummiformis, displaying maximum AOA potential indicated a preponderance of tannic acid, gallic acid, protocatacheuic acid, and gentisic acid. Studies thus provide the precise antioxidant status of 23 indigenous species of mushrooms, which can serve as a useful database for the selection of mushrooms for the function of preparation of mushroom-based nutraceutics.     

Antioxidant activities of sicilian prickly pear (Opuntia ficus indica) fruit extracts and reducing properties of its betalains: betanin and indicaxanthin

Sicilian cultivars of prickly pear (Opuntia ficus indica) produce yellow, red, and white fruits, due to the combination of two betalain pigments, the purple-red betanin and the yellow-orange indicaxanthin. The betalain distribution in the three cultivars and the antioxidant activities of methanolic extracts from edible pulp were investigated. In addition, the reducing capacity of purified betanin and indicaxanthin was measured. According to a spectrophotometric analysis, the yellow cultivar exhibited the highest amount of betalains, followed by the red and white ones. Indicaxanthin accounted for about 99% of betalains in the white fruit, while the ratio of betanin to indicaxanthin varied from 1:8 (w:w) in the yellow fruit to 2:1 (w:w) in the red one. Polyphenol pigments were negligible components only in the red fruit. When measured as 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid (Trolox) equivalents per gram of pulp, the methanolic fruit extracts showed a marked antioxidant activity. Vitamin C did not account for more than 40% of the measured activity. In addition, the extracts dose-dependently inhibited the organic hydroperoxide-stimulated red cell membrane lipid oxidation, as well as the metal-dependent and -independent low-density lipoprotein oxidation. The extract from the white fruit showed the highest protection in all models of lipid oxidation. Purified betanin and indicaxanthin were more effective than Trolox at scavenging the [2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid)] diammonium salt cation radical. Cyclic voltammetric measurements show two anodic waves for betanin and indicaxanthin, and differential pulse voltammetry shows three anodic waves for betanin, with calculated peak potentials of 404, 616, and 998 mV, and two anodic waves for indicaxanthin, with peak potentials of 611 and 895 mV. Betanin underwent complex formation through chelation with Cu(2+), whereas indicaxanthin was not modified. These findings suggest that the above betalains contribute to the antioxidant activity of prickly pear fruits.     

Antioxidant activity and total phenolics in selected cereal grains and their different morphological fractions

The purpose of this study was to examine the antioxidant properties of water and 80% methanolic extracts of cereal grains and their different morphological fractions. Wheat (Triticum aestivum L.) cv. Almari and cv. Henika, barley (Hordeum vulgare L.) cv. Gregor and cv. Mobek, rye (Secale cereale L.) cv. Dańkowskie Zlote, oat (Avena sativa L.) cv. Slawko and buckwheat (Fagopyrum esculentum Moench) cv. Kora were used. PC (L-alpha-phosphatidylcholine) liposome system and spectrophotometric assay of total antioxidant activity (TAA) were used to evaluate the antioxidative activity of extracts. Among the water extracts, only the one prepared from buckwheat exhibited antioxidant activity at the concentration analyzed. The following hierarchy of antioxidant activity was provided for 80% methanolic extracts originated from whole grain: buckwheat > barley > oat > wheat congruent with rye. The antioxidant activity was observed in extract prepared from separated parts of buckwheat and barley. In respect to hulls, the antioxidant hierarchy was as follows: buckwheat > oat > barley. The correlation coefficient between total phenolic compounds and total antioxidative activity of the extracts was -0.35 for water extracts and 0.96, 0.99, 0.80, and 0.99 for 80% methanolic extracts originated from whole grains, hulls, pericarb with testa fractions and endosperm with embryo fractions, respectively.     

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.     

Antioxidative activity and safety of the 50 ethanolic extract from red bean fermented by Bacillus subtilis IMR-NK1

This study aimed at evaluating the antioxidative activities and the safety of 50% ethanolic extract from red bean fermented by Bacillus subtillis IMR-NK1. The antioxidative activities, including alpha,alpha-diphenyl-beta-picryl-hydrazyl (DPPH) radicals scavenging effects, Fe(2+)-chelating ability, and reducing power, were studied in vitro. It was found that the antioxidative activity increased with the concentrations of the extract to a certain extent and then leveled off as the concentration further increased. As compared to the commercial antioxidants, the fermented red bean extract showed less scavenging effect on the DPPH radical and reducing power than alpha-tocopherol and BHT, but better Fe(2+)-chelating ability. No mutagenicity or toxicity effect toward all tester strains was found in the 50% ethanolic extract of fermented red bean by means of the Ames test. The results suggested that the 50% ethanolic extract was safe in genotoxicity.     

Antioxidant activities and antitumor screening of extracts from cranberry fruit (Vaccinium macrocarpon)

Polyphenolic compounds in cranberries have been investigated to determine their role in protection against cardiovascular disease and some cancers. Extracts of whole fruit were assayed for radical-scavenging activity and tumor growth inhibition using seven tumor cell lines. Selective inhibition of K562 and HT-29 cells was observed from a methanolic extract in the range of 16-125 microg/mL. Radical-scavenging activity was greatest in an extract composed primarily of flavonol glycosides. Seven flavonol glycosides were isolated and purified from whole fruit for further evaluation; the anthocyanin cyanidin 3-galactoside was also purified for comparison with the flavonoids. Three flavonol monoglycosides were newly identified by (13)C NMR as myricetin 3-alpha-arabinofuranoside, quercetin 3-xyloside, and 3-methoxyquercetin 3-beta-galactoside (isorhamnetin); the other four isolated were the previously identified myricetin 3-beta-galactoside, quercetin 3-beta-galactoside, quercetin 3-alpha-arabinofuranoside, and quercetin 3-alpha-rhamnopyranoside. These compounds were evaluated for 1,1-diphenyl-2-picrylhydrazyl radical-scavenging activity and ability to inhibit low-density lipoprotein oxidation in vitro. Most of the flavonol glycosides showed antioxidant activity comparable or superior to that of vitamin E; cyanidin 3-galactoside showed activity superior to that of the flavonoids as well as vitamin E or Trolox in both antioxidant assays.     

Antioxidant effects of extracts from Cassia tora L. prepared under different degrees of roasting on the oxidative damage to biomolecules

The effects of water extracts from Cassia tora L. (WECT) treated with different degrees of roasting (unroasted and roasted at 150, 200, and 250 degrees C) on the oxidative damage to deoxyribose, DNA, and DNA base in vitro were investigated. It was found that WECT alone induced a slight strand breaking of DNA. In the presence of Fe(3+)/H(2)O(2), WECT accelerated the strand breaking of DNA at a concentration of 2 microg/mL; however, it decreased with increasing concentrations (>5 microg/mL) of WECT. WECT also accelerated the oxidation of deoxyribose induced by Fe(3+)-EDTA/H(2)O(2) at a concentration of 0.2 mg/mL but inhibited the oxidation of deoxyribose induced by Fe(3+)-EDTA/H(2)O(2)/ascorbic acid. Furthermore, WECT accelerated the oxidation of 2'-deoxyguanosine (2'-dG) to form 8-OH-2'-dG induced by Fe(3+)-EDTA/H(2)O(2). The prooxidant action of WECT on the oxidation of 2'-dG was in the order of unroasted > roasted at 150 degrees C > roasted at 200 degrees C > roasted at 250 degrees C. The decrease in the prooxidant activity of the roasted sample might be due to the reduction in its anthraquinone glycoside content or the formation of antioxidant Maillard reaction products after roasting. Thus, WECT exhibited either a prooxidant or an antioxidant property in the model system that was dependent on the activities of the reducing metal ions, scavenging hydroxyl radical, and chelating ferrous ion.     

Chemical composition, iron bioavailability, and antioxidant activity of Kappaphycus alvarezzi (Doty)

Kappaphycus alvarezzi, an edible seaweed from the west coast of India, was analyzed for its chemical composition. It was found that K. alvarezzi is rich in protein (16.24% w/w) and contains a high amount of fiber (29.40% w/w) and carbohydrates (27.4% w/w). K. alvarezzi showed vitamin A activity of 865 mug retinal equivalents/100 g of sample. It contained a higher quantity of unsaturated fatty acids (44.50% of the total), in which relative percentage of oleic acid was 11%, cis-heptadecanoic acid 13.50%, and linoleic acid 2.3% and 37.0% of saturated fatty acids (mainly heptadecanoic acid). K. alvarezziwas also found to be good source of minerals, viz 0.16% of calcium, 0.033% of iron, and 0.016% of zinc, which are essential for various vital biological activities. Bioavailability of iron by in vitro methods showed a higher efficiency in intestinal conditions than in stomach conditions. Ascorbic acid influenced higher bioavailability of iron. Successive extracts of n-hexane, acetone, ethyl acetate, ethanol, and direct extractables of chloroform/methanol (1:1 and 2:1) were screened for antioxidant activity using a beta-carotene linoleic acid model system (B-CLAMS), DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) model system and hydroxyl radical scavenging activity. The chloroform/methanol (2:1) extract has shown 82.5% scavenging activity at 1000 ppm. Acetone fraction extracts at the 1000 ppm level showed 63.31% antioxidant activity in beta-carotene linoleic acid system. The acetone extract showed 46.04% scavenging activity at 1000 ppm concentration. In the case of hydroxyl radical scavenging activity, all the extracts showed better activity at the concentrations of 25 and 50 ppm, where at the 50 ppm level ethyl acetate extract showed 76.0%, acetone 75.12%, and hexane 71.15% activity, respectively. Results of this study suggest the utility of K. alvarezzi (Eucheuma) for various nutritional products, including antioxidant for use as health food or nutraceutical supplement.     

Phenolics composition and antioxidant activity of sweet basil (Ocimum basilicum L.)

The antioxidant activity of a methanolic extract of Ocimum basilicum L. (sweet basil) was examined using different in vitro assay model systems. The crude extract was fractionated on a Sephadex LH-20 column, and six fractions were identified. The DPPH scavenging assay system and the oxidation of the soy phosphotidylcholin liposome model system were used to evaluate the antioxidant activity of each fraction. Fraction IV showed the strongest activity followed by fractions V and VI. Phenolic compounds responsible for the antioxidative activity of the fractions were characterized by atmospheric pressure chemical ionization liquid chromatography-mass spectrometry. The major antioxidant compound in fraction IV was confirmed as rosmarinic acid by (1)H NMR and characteristic fragmentations in the mass spectrum. Moreover, the native of antioxidant activity of rosmarinic acid in the liposome system was examined. The results showed that one rosmarinic acid can capture 1.52 radicals, and furthermore, the existence of a synergistic effect between alpha-tocopherol and rosmarinic acid was revealed.     

Antioxidant activity of extracts, condensed tannin fractions, and pure flavonoids from Phaseolus vulgaris L. seed coat color genotypes

Twelve different seed coat color genotypes of Phaseolus vulgaris L. were extracted and pure flavonoids isolated from 10 of these. The seed coat methanol extracts, tannin fractions, and pure flavonoids all displayed antioxidant activity in a fluorescence-based liposome assay. The relatively high activity of the condensed tannin (proanthocyanidin) fractions indicates that these may play an important role in the overall activity of the extracts. This activity also indicates that although these polyphenols cause problems in digestibility, they may be important dietary supplements with beneficial health effects. The pure anthocyanins delphinidin 3-O-glucoside (1), petunidin 3-O-glucoside (2), and malvidin 3-O-glucoside (3) and the flavonol quercetin 3-O-glucoside (4) isolated from seed coats also had significantly higher antioxidant activity than the Fe(2+) control. The activity of kaempferol 3-O-glucoside (5) was not different from that of the Fe(2+) control. These findings suggest that variously colored dry beans may be an important source of dietary antioxidants.     

大孔树脂分离纯化玫瑰果多酚及其抗氧化性

为了研究大孔树脂对玫瑰果多酚的纯化效果,该试验以玫瑰果多酚粗提液为原料,利用大孔树脂吸附法对其进行纯化,并对其体外抗氧化活性进行了研究。结果表明,大孔吸附树脂纯化较佳工艺为:在20℃条件下,用质量浓度为0.80 mg/m L的玫瑰果多酚粗提液(p H值5.8)以1 m L/min的流速上样200 m L;吸附平衡后用少量蒸馏水洗至洗脱液无色,后用70 m L体积分数为70%的乙醇溶液,以1.5 m L/min的流速进行动态洗脱,洗脱峰相对集中、对称,无拖尾。纯化后,总酚质量分数由纯化前的122.90 mg/g提高到399.42 mg/g。体外抗氧化活性的研究表明:清除1,1-二苯基-2-苦基肼自由基的作用效果顺序为维生素C纯化多酚2,6-二叔丁基-4-甲基苯酚(Butylated hydroxytoluene,BHT)粗多酚;清除超氧阴离子自由基的作用效果顺序为维生素CBHT纯化多酚粗多酚;清除羟基自由基的作用效果顺序为维生素C纯化多酚BHT粗多酚。研究结果为玫瑰果多酚的进一步利用提供依据。     

Antioxidant activity in common beans (Phaseolus vulgaris L.)

Beans were pearled to evaluate the feasibility of increasing antioxidant activity and phenolic antioxidants. Phenolics were concentrated mostly in the hull fraction at about 56 mg of catechin equivalents per gram of sample. The methanolic extracts of the pearled bean samples were screened for antioxidant potential using the beta-carotene-linoleate and the 1,1-diphenyl-2-picrylhydrazyl (DPPH) in vitro model systems. The pearled material, also referred to as milled samples, exhibited antioxidant activity that correlated with phenolic content and inhibited DPPH significantly in a dose-dependent manner. Phenolics and antioxidant activities were also examined in chromatographic fractions of methanolic extracts of manually obtained hulls that represented a model used previously to ascertain antimutagenic activity. Fractions extracted with ethyl acetate/acetone and acetone displayed antioxidant activity, which implies potent free radical scavenging activity with antimutagenic activity.     

Evolution of phenolic composition of red wine during vinification and storage and its contribution to wine sensory properties and antioxidant activity

The objective of this work was to study the evolution of the phenolic composition of red wine during vinification and storage and its relationship with some sensory properties (astringency and bitterness) and antioxidant activities. Thus, red wine was made by a classic vinification method with Castela?o and Tinta Miu?da grapes (Vitis vinifera L.) harvested at maturity (3:2; w/w). Samples were taken at 2 and 7 days of maceration, at second racking, at the time of bottling and at 6 and 14 months after bottling. The total polyphenols extract (TPx) in each sample was isolated by column chromatography. The phenolic composition (anthocyanins and proanthocyanidins), in vitro antioxidant activity, and sensory property (astringency, bitterness) of the isolated TPx from different winemaking stages were evaluated through high-performance liquid chromatography-diode array detection, 1,1-diphenyl-2-picrylhidrazyl radical test, ferric reducing antioxidant power assay, total phenolic index, MWI (polyphenol molecular weight index), TSA (tannin specific activity), and sensory panel tasting. The results showed that the phenolic composition of red wine varied significantly during winemaking. The intensity of astringency (IA) and the intensity bitterness (IB) of the isolated TPx from different winemaking stages increased from 2 days of maceration until second racking and then decreased. Furthermore, MWI and TSA are positively correlated with IA and IB. The in vitro antioxidant activity of the isolated TPx from different winemaking stages maintained unchanged after alcoholic fermentation, which was independent of the variation of phenolic composition and sensory properties.     

Isolation and characterization of antioxidant protein fractions from melinjo (Gnetum gnemon) seeds

The protein from the seeds of melinjo ( Gnetum gnemon ) was purified using a precipitation method and ion exchange chromatographic techniques to identify the potent antioxidant and free radical scavenging activities. Two antioxidant protein fractions were isolated from G. gnemon seed with molecular weights of approximately 30 kDa (Gg-AOPI) and 12 kDa (Gg-AOPII) by SDS-PAGE. The N-terminal amino acid sequence of Gg-AOPII is Gly-Asn-Gly-Lys-Ala-Thr-Val-Ala-Ile-Leu-Val-Lys-Glu-Lys-Val-Glu-Tyr-Gly-Glu-Glu, and the result of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis showed that they were distinct from each other; no protein in database matching was found to both Gg-AOPI and Gg-AOPII. The antioxidant or free radical scavenging activities of Gg-AOPs were investigated by employing in vitro assay systems including the inhibition of linoleic acid autoxidation, scavenging effect on α,α-diphenyl-β-picrylhydrazyl free radical (DPPH), 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), reducing power, chelating abilities of metal ions Cu(2+) and Fe(2+), and protections against hydroxyl radical-mediated DNA damages. The result showed that two protein fractions exhibited significant (p < 0.05) antioxidant activities against free radicals such as DPPH, ABTS, and superoxide anion and showed activities similar to those of glutathione (G-SH) and BHT in a linoleic acid emulsion assay system. Moreover, Gg-AOPI and Gg-AOPII also exhibited notable reducing power and strong chelating effect on Fe(2+) and protected hydroxyl radical induced oxidative DNA damage. The data obtained by the in vitro systems obviously established the antioxidant potency of Gg-AOPs.     

β-Carotene Assay Revisited. Application To Characterize and Quantify Antioxidant and Prooxidant Activities in a Microplate

The β-carotene bleaching assay, a common method for evaluating antioxidant activity, has been widely criticized due to its low reproducibility, problematic quantification, complex reagent preparation, and interference of different factors (temperature, pH, solvents, and metals). In this work we have examined the effects of these factors and developed a highly reproducible procedure for microplate assay, evaluated the critical points of the method, and proposed a kinetic model for quantifying both antioxidant and prooxidant activities. The application of these tools produced very consistent results, which provide robust and meaningful criteria to compare in detail the characteristics of several well-known commercial antioxidants, as well as several predictable prooxidants, and can be easily applied to natural extracts, food samples, and many other type of compounds. As an example, we have tested a set of commercial antioxidants and some typical lipophilic prooxidants. The activity of the tested antioxidants decreased in the following order: ethoxyquin ? α-tocopherol > butylhydroxyanisole > butylhydroxytoluene ? propyl gallate. On the other hand, hemoglobin and Fe(2+), Fe(3+), Co(2+), and Cu(2+) showed a strong prooxidant effect, and the activity was null in Cd(2+), Ni(2+), and Sr(2+), slightly antioxidant in Mg(2+), and strongly antioxidant in Zn(2+) and Mn(2+).