Contributions of major components to the antimutagenic effect of Hsian-tsao (Mesona procumbens Hemsl.).

Our aim was to determine the antimutagenic activity of various solvent extracts from an herb Mesona procumbens Hemsl, normally called Hsian-tsao in China. We also investigated the relationships between the special components in the water extract of Hsian-tsao (WEHT) and the antimutagenic activity. It was found that the extracts at 0-0.6 mg/plate from three solvents (water, methanol, and ethyl acetate) exhibited a dose-dependent antimutagenic effect against benzo[a]pyrene [B(a)P] and 2-amino-3-methylimidazo(4,5-f)quinoline (IQ), both are indirect mutagens in Salmonella tester strains TA98 and TA100. The WEHT from three different plantations revealed a similar inhibitory effect on the mutagenicity of IQ in TA 98 at 2.5-5.0 mg/plate. The inhibitory effect of WEHT on the mutagenicity of IQ correlates with their polyphenol and ascorbic acid contents but not with their chlorophyll contents. These findings suggest that the antimutagenicity activity of WEHT may be attributed mainly to their polyphenolic compounds and ascorbic acid.

Evaluation of the cytotoxicity, mutagenicity and antimutagenicity of emerging edible plants.

This study evaluates the toxic, mutagenic and antimutagenic effects of emerging edible plants that are consumed as new leafy vegetables in Taiwan. Among eight plant extracts, only the extracts of Sol (Solanum nigrum L.) showed cytotoxicity to Salmonella typhimurium TA100 in the absence of S9 mix. The toxicity of extracts from different parts of the Sol plant, such as leaf and stem, immature fruit and mature fruit, towards S. typhimurium TA100 and human lymphocytes was also assayed. The immature fruit extracts of Sol exhibited strong cytotoxicity with dose dependence and induced significant DNA damage in human lymphocytes based on the comet assay. However, no mutagenicity was found in eight plant extracts to TA98 or TA100 either with or without the S9 mixture. Sol and Sec [Sechium edule (Jacq.) Swartz] extracts showed the strongest inhibitory effect towards the mutagenicity of 2-amino-3-methyl-imidazo[4,5-f]quinoline (IQ) in S. typhimurium TA98 and TA100; the ID(50) was less then 1 mg/plate. Cra [Crassocephalum creidioides (Benth.) S. Moore] extracts also expressed moderate antimutagenic activities towards IQ and benzo[a]pyrene (B[a]P) either in TA98 or in TA100; the ID(50) was 1.63-2.41 mg/plate. The extracts from Bas (Basella alba L.), Bou (Boussingaultia gracilis Miers var. pseudobaselloides Bailey), Cen (Centella asiatica L. Urban), Cor (Corchorus olitorius L.) and Por (Portulaca oleracea L.) showed weak to moderate inhibition of mutagenicity of IQ. However, the potential antimutagenicity of these plant extracts towards B[a]P was weaker than that towards IQ. For a direct mutagen, 4-nitroquinoline-N-oxide (NQNO), only the Sol extracts showed strong inhibitory effects in the TA100 system. The antimutagenic activity of water extracts of Sec was partly reduced by heating at 100 degrees C for 20 min. The heat-stable antimutagens in Sec extracts could be produced in the plant extract preparation process. Fractions with molecular weights above 30,000 showed the strongest antimutagenicity and peroxidase activity in all the fractions of the Sec extracts.

Inhibitory effects of Cassia tora L. on benzo[a]pyrene-mediated DNA damage toward HepG2 cells.

The effects of water extracts from Cassia tora L. (WECT) treated with different degrees of roasting on benzo[a]pyrene (B[a]P)-induced DNA damage in human hepatoma cell line HepG2 were investigated via the comet assay without exogenous activation mixtures, such as S9 mix. WECT alone, at concentrations of 0.1-2 mg/mL, showed neither cytotoxic nor genotoxic effect toward HepG2 cells. B[a]P-induced DNA damage in HepG2 cells could be reduced by WECT in a dose-dependent manner (P < 0.05). At a concentration of 1 mg/mL, the inhibitory effects of WECT on DNA damage were in the order unroasted (72%) > roasted at 150 degrees C (60%) > roasted at 250 degrees C (23%). Ethoxyresorufin-O-dealkylase activity of HepG2 cells was effectively inhibited by WECT, and a similar trend of inhibition was observed in the order unroasted (64%) > roasted at 150 degrees C (42%) > roasted at 250 degrees C (18%). The activity of NADPH cytochrome P-450 reductase was also decreased by unroasted and 150 degrees C-roasted samples (50% and 38%, respectively). Furthermore, glutathione S-transferase activity was increased by treatment with unroasted (1.26-fold) and 150 degrees C-roasted (1.35-fold) samples at 1 mg/mL. In addition, the contents of anthraquinones (AQs) in WECT, including chrysophanol, emodin, and rhein, were decreased with increasing roasting temperature. Each of these AQs also demonstrated significant antigenotoxic activity in the comet assay. The inhibitory effects of chrysophanol, emodin, and rhein on B[a]P-mediated DNA damage in HepG2 cells were 78, 86, and 71%, respectively, at 100 microM. These findings suggested that the decreased antigenotoxicity of the roasted samples might be due to a reduction in their AQs content.

Isolation and characterization of antioxidant compounds from Aspergillus candidus broth filtrate.

The objectives of this study were to isolate the antioxidative components in the broth filtrate of Aspergillus candidus (CCRC 31543), to characterize their antioxidative properties, and to evaluate their safety. Three major compounds were isolated and identified as 3,3' '-dihydroxyterphenyllin, 3-hydroxyterphenyllin, and candidusin B. In the linoleic acid peroxidation system, the inhibition of peroxidation in these three compounds was greater than 95% and was significantly higher than that of alpha-tocopherol but equal to that of BHA at 12.5-200 microg/mL. As measured using the Rancimat method in lard, 3,3' '-di-OH-terphenyllin exhibited a protection factor value of 7.82, which was substantially higher than those of BHA (5.58) and alpha-tocopherol (4.29) at 200 microg/mL. 3,3' '-di-OH-terphenyllin and 3-OH-terphenyllin also exhibited marked scavenging effects on the alpha,alpha-diphenyl-beta-picrylhydrazyl radicals (94.7 and 96.0%, respectively), which were similar to those of BHA and alpha-tocopherol. Safety studies showed that these three compounds were neither cyto- nor geno-toxic toward human intestine 407 (INT 407) cells, nor mutagenic toward Salmonella typhimurium TA98 and TA100.

Antioxidant effects of water extracts from barley (Hordeum vulgare L.) prepared under different roasting temperatures.

The antioxidant effects of water extracts of roasted barley (WERB) were investigated under different roasting temperatures and compared with those of the water extracts of unroasted barley (WEUB). It was found that the Maillard reaction products increased upon increasing the roasting temperatures. Both WERB and WEUB exhibited significant antioxidant activities in linoleic acid and liposome model systems. Although WERB and WEUB afforded considerable protection against the damage of deoxyribose and proteins, the antioxidant efficiency of roasted samples was weaker than that of unroasted samples because of the reduction of antioxidant components (catechin, tocopherol, and lutein) with increasing roasting temperature. Unroasted samples were more effective in reducing power, quenching free radical, hydroxyl radical, and chelating iron than the roasted samples. The different antioxidant activity among roasted and unroasted barley samples may be partly attributed to the changes in catechin, tocopherol, and lutein contents.

Suppression effect of soy isoflavones on nitric oxide production in RAW 264.7 macrophages.

Genistein, daidzein, and glycitein, as primary isoflavones in soybeans, are reported to have beneficial effects on atherosclerosis, chronic inflammatory diseases, and cancers that are conducted by nitric oxide (NO) injury. The objectives of this study were to investigate the effects and mechanisms of these soy isoflavones on the inducible nitric oxide synthase (iNOS) system in lipopolysaccharide (LPS)-activated RAW 264.7 macrophages. Genistein, daidzein, and glycitein dose-dependently suppress NO production (IC(50) = 50 microM) in supernatants of LPS-activated macrophages as measured on the basis of nitrite accumulation. In addition, direct inhibition of iNOS activity, determined by means of the conversion of L-[(3)H]arginine to L-[(3)H]citrulline, and markedly reduced iNOS protein and mRNA levels, evaluated by means of Western blot and RT-PCR, respectively, were found in homogenates of LPS-activated cells treated with each isoflavone. Moreover, genistein was found to have a greater inhibitory effect on NO production but no significant effect on iNOS activity or protein and gene expression to daidzein and glycitein. These observations reveal that the suppression of NO production by genistein, daidzein, and glycitein might be due to the inhibition of both the activity and expression of iNOS in LPS-activated macrophages. The result suggests that soy isoflavones might attenuate excessive NO generation at inflammatory sites.

Mutagenicity and identification of mutagenic compounds of fumes obtained from heating peanut oil.

Since the fume of cooking oil has been reported to increase the risk of lung cancer, the objectives of this study were to evaluate the mutagenicity and to find the mutagens in the fumes of peanut oil heated to the smoke point. Peanut oil prepared from roasted peanut kernel showed a lower smoke point, less unsaturated fatty acids, more fume formation, and stronger mutagenicity than that from unroasted kernel. Further investigation of mutagenic compounds was performed by the Ames test and gas chromatography/mass spectrometry analysis. Among the 12 compounds identified from the neutral fraction of methanol extract, four compounds at a dose of 10 microg per plate were mutagenic to Salmonella Typhimurium TA98 and TA100 in the order of trans-trans-2,4-decadienal > trans-trans-2,4-nonadienal > trans-2-decenal > trans-2-undecenal. Results report the enal compounds formed as the mutagens in the fumes of peanut oil and indicate that inhaling cooking fumes might cause carcinogenic risk.

Reactive oxygen species scavenging activity of Du-zhong (Eucommia ulmoides oliv.) and its active compounds.

The biologically active compounds and free radical-/ or reactive oxygen species (ROS)-/ scavenging effect of water extract from Du-zhong (WEDZ) were investigated. The WEDZ used included leaves, raw cortex, and roasted cortex. The hot water extract of Du-zhong leaves showed marked activity as a ROS scavenger, and the scavenging effect was concentration dependent. The extract of roasted cortex exhibited a modest scavenging effect on ROS, while the extract of raw cortex had the weakest scavenging effect. The scavenging activity of WEDZ on ROS was correlated to its protocatechuic acid (PCA) content. The content of PCA in Du-zhong determined by HPLC followed the order of leaves (17.17 mg/g) > roasted cortex (2.99 mg/g) > raw cortex (1.16 mg/g). The inhibitory activity of leaf extract of Du-zhong was stronger than that of PCA on the peroxidation of linoleic acid at the same concentration of 0.1 mg/mL. The results presented herein indicated that extract of Du-zhong could possibly act as a prophylactic agent to prevent free radical-related diseases.

Protective effect of extracts of Mesona procumbens Hemsl. on DNA damage in human lymphocytes exposed to hydrogen peroxide and UV irradiation.

In the present study, the protective effect of water extracts from Hsian-tsao (WEHT) on DNA damage in human lymphocytes induced by UV-C and/or H(2)O(2) was evaluated using single-cell electrophoresis (comet assay). No toxicity was found in WEHT towards human lymphocytes. WEHT did not cause DNA damage at lower concentrations of 0.05 and 0.1 mg/ml, while it did cause slight DNA damage at a concentration of 0.5-2.5 mg/ml when compared with the control group. When WEHT was mixed with H(2)O(2) for reaction, it exhibited a slight inhibitory effect on DNA damage induced by H(2)O(2). Moreover, when WEHT and lymphocytes were irradiated by UV-C and then incubated for 35 min, the DNA damage decreased with an increase of the concentration of WEHT. Thus, WEHT could reduce UV-C-induced DNA damage, and WEHT had a more protective effect on UV-C than on H(2)O(2)-induced DNA damage. The protective effect of WEHT on DNA damage might be due to the fact that it contains polyphenol compounds and/or other active components.

Antioxidant properties of water extracts from Cassia tora L. in relation to the degree of roasting.

The antioxidant properties of water extracts from Cassia tora L. (WECT) prepared under different degrees of roasting were investigated. The water extracts of unroasted C. tora L. (WEUCT) showed 94% inhibition of peroxidation of linoleic acid at a dose of 0.2 mg/mL, which was higher than that of alpha-tocopherol (82%). Water extracts prepared from C. tora L. roasted at 175 degrees C for 5 min and at 200 degrees C for 5 min exhibited 83% and 82%, respectively, inhibition of linoleic acid peroxidation. This result indicated that the antioxidant activities of WECT decreased with longer roasting time or higher roasting temperature. The IC(50) of WEUCT in liposome oxidation induced by the Fenton reaction was 0.41 mg/mL, which was higher than that of alpha-tocopherol (IC(50) = 0.55 mg/mL). WEUCT also exhibited good antioxidant activity in enzymatic and nonenzymatic microsome oxidative systems. The water extracts of roasted C. tora L. increased in the degree of browning and produced chemiluminescence when compared with the unroasted sample. However, the total polyphenolic compounds of WECT decreased after the roasting process finished. In conclusion, the decrease in the antioxidant activity of water extracts from roasted C. tora L. might have been due to the degradation of Maillard reaction products and the decrease of polyphenolic compounds.

Antioxidant actions of du-zhong (Eucommia ulmoides Oliv.) toward oxidative damage in biomolecules.

This study aimed to investigate the antioxidant effect of water extracts of Du-zhong (WEDZ) on oxidative damage in biomolecules such as deoxyribose, DNA, and 2'-deoxyguanosine (2'-dG) as induced by Fenton reaction. The WEDZ used included leaves, raw cortex, and roasted cortex. All of the WEDZ inhibited the oxidation of deoxyribose induced by Fe(3+)-EDTA/H2O2/ascorbic acid in a concentration dependent manner. At a concentration of 1.14 mg/mL, the inhibitory effect of the extracts of leaves, roasted cortex, and raw cortex was 85.2%, 68.0% and 49.3%, respectively. The extract of leaves inhibited the strand-breaking of DNA induced by the Fenton reaction at concentrations of 5 and 10 micrograms/microL. This inhibitory effect was similar to mannitol whereas the extracts of raw cortex and roasted cortex had no inhibitory effect at all. WEDZ also inhibited the oxidation of 2'-dG to 8-OH-2'-dG induced by Fe(3+)-EDTA/H2O2/ascorbic acid. Gallic acid had a prooxidant effect, but trolox and mannitol had an antioxidant effect. The leaf extract had a marked inhibitory effect on Fenton reaction induced oxidative damage in biomolecules. The extract of roasted cortex exhibited modest inhibition while the extract of raw cortex had the least inhibitory effect on oxidative damage in biomolecules. This is in contrast to gallic acid in the same reaction system, whose higher reducing power and weaker chelating ability may contribute to its prooxidant effect. In the present study, leaf extract of Du-zhong had inhibitory effect on oxidative damage in biomolecules. Therefore, drinking of Du-zhong tea (leaf extract) over a long period of time may have anticancer potential.

Changes in volatile flavor components of guava juice with high-pressure treatment and heat processing and during storage.

The changes in volatile flavor components of guava juice during pressure processing (25 degrees C, 600 MPa, 15 min), heat processing (95 degrees C, 5 min), and storage at 4 and 25 degrees C were evaluated by purge and trap/gas chromatography/mass spectrometry. Esters were the major volatile fraction in guava juice, and alcohols were the second. Pressure processing could maintain the original flavor distribution of the juice. Heat processing (95 degrees C, 5 min) caused decreases in the majority of flavor components in the juice when compared with freshly extracted juice. High-pressure treatment at 600 MPa for 15 min can effectively sterilize microbes but partially inactivate enzymes of guava juice; therefore, volatile components in pressure-treated juice gradually changed during storage periods. Pressure-treated guava juice showed increases in methanol, ethanol, and 2-ethylfuran with decreases in the other components during storage period. Nevertheless, the volatile distribution of 600 MPa treated guava juice was similar to that of freshly extracted juice when stored at 4 degrees C for 30 days.

Action of methanolic extract of mung bean hulls as inhibitors of lipid peroxidation and non-lipid oxidative damage.

The antioxidant effects of methanolic extract of mung bean hulls (MEMBH) on lipids and non-lipids, including liposome, carbohydrate, protein and 2'-deoxyguanosine (2'-dG), were investigated. MEMBH exhibited a remarkable antioxidant effect in a liposome model system, indicating that the extract was an inhibitor of lipid peroxidation. The inhibitory effect of MEMBH on deoxyribose damage was amount-dependent and it afforded considerable protection against damage to deoxyribose. In addition, MEMBH at low amounts was more effective in protecting protein oxidation. Furthermore, the oxidation of 2'-dG to 8-hydroxy-2'-deoxyguanosine (8-OH-2'dG) was inhibited by MEMBH. These results show that the extract also was an inhibitor of non-lipid oxidation damage. The extract exhibited metal binding ability and scavenging activity for hydrogen peroxide and hydroxyl radical, which may explain the mechanism of their protecting lipids and non-lipids from oxidative damage.

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.

Medium optimization for the production of antioxidants from Aspergillus candidus.

The objective of this study was to optimize the factors for the production of antioxidant from Aspergillus candidus CCRC 31543. Extracts of broth filtrate had higher antioxidant activity (inhibition of peroxidation [IP] >98%) when sucrose or lactose was used as a carbon source. Sucrose in the medium also resulted in a higher yield of extracts. Ethyl acetate extracts had the highest yield and antioxidant activity compared with the other two solvents. For the production of antioxidant, inorganic nitrogen sources were found to be more suitable than organic nitrogen sources, and ammonium sulfate was better than sodium nitrate. Yeast extract had a strong influence on the yield of antioxidant extracts. Both mycelium and broth filtrate of A. candidus CCRC 31543 showed similar antioxidant activity (IP = 95%), and they also had similar extraction yields.

Scavenging effect of various tea extracts on superoxide derived from the metabolism of mutagens.

We determine the superoxide formed in the self-degradation of mutagens activated by cytochrome enzymes and evaluated the scavenging effect of various tea extracts. Benzo[a]pyrene (B[a]P) and 2-amino-6-methyldipyrido(1,2-a:3',2'-d)imidazole (Glu-P-1) each produced a large amount of superoxide after activation by cytochrome enzymes. However, 2-amino-3-methyl-imidazo(4,5-f)quinoline (IQ), 3-amino-1,4-dimethyl-5H-pyridol(4,3-b)indole (Trp-P-1) and alfatoxin B1 (AFB1) failed to generate a significant amount of superoxide. The addition of a tea extract to the reaction system marked inhibited the derivation of superoxide from Glu-P-1. However, the tea extracts showed weaker inhibition of the B[a]P-mediated formation of superoxide. Among the four teas tested, the oolong tea extract tended to exhibit the strongest inhibitory effect. Our results suggest that the chemopreventive efficacy of a tea extract is partly associated with its antioxidative activity.

High pressure and heat treatments effects on pectic substances in guava juice.

Effects of high pressure treatment on changes in pectic substances in guava juice were investigated and compared with those of heat treated samples. The viscosity and turbidity of guava juice pressurized at 6000 atm and 25 degrees C for 10 min increased slightly, whereas the viscosity of juice heated at 95 degrees C for 5 min decreased from 362 to 285 cps while turbidity increased from 0.87 to 1.15 (OD 600 nm). There were no apparent changes in water soluble, oxalate soluble and alkali soluble pectins in the pressurized juice. However, heat treated juice exhibited a decrease in its water and alkali soluble pectins and a slight increase in oxalate soluble pectin. The DEAE-cellulose profiles of pectic substances in guava juice were apparently unchanged after high pressure treatment while they were markedly changed by heat treatment, due to coagulation or degradation. During thermal processing, the degradation of pectin in guava juice caused a decrease in viscosity while the coagulation of pectin resulted in an increase in turbidity and cloud content. High pressure treatment showed no marked changes in pectic substances and cloud content in guava juice and maintained its natural viscous properties.

Antioxidative and Prooxidative Actions of Xylose-Lysine Maillard Reaction Products.

Maillard reaction products were prepared by heating xylose and lysine at pH 9.0 and 100°C for 3 h, and then fractionated by ethyl ether and ethanol into acidic, neutral and basic low-molecular-weight, ethanol-soluble and ethanol-insoluble fractions. The ethanol-soluble and -insoluble fractions were the major fractions of the xylose-lysine Maillard reaction products (XL MRPs), contributing 79.5% and 20.1%, respectively. XL MRPs revealed an inhibitory effect on linoleic acid peroxidation induced by the Fenton reaction, but did not inhibit liposome peroxidation induced by Fe(2+), where it had a prooxidative action. XL MRPs caused oxidative damage to deoxyribose and 2'-deoxyguanosine (2'-dG) induced by the Fenton reaction. The ethanol-soluble and -insoluble fractions also caused oxidative damages while the low-molecular-weight fractions displayed an antioxidative effect in inhibiting the oxidative damage to deoxyribose that was induced by the Fenton reaction. The prooxidative action of the ethanol-soluble and -insoluble fractions resembled that of the untractionated products in the 2'-dG assay. In these systems with deoxyribose, 2'-dG, linoleic acid and liposomes, XL MRPs exhibited either antioxidative or prooxidative properties, which might have been due to competition between their reducing power and scavenging activity toward the hydroxyl radical. However, the low-molecular-weight fractions did not show any prooxidative activity in these oxidation systems.

Possible mechanisms of antimutagens by various teas as judged by their effects on mutagenesis by 2-amino-3-methylimidazo[4,5-f]quinoline and benzo[a]pyrene.

Possible mechanisms of antimutagenicity of various tea extracts (green, pouchong, oolong and black tea) toward 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) and benzo[a]pyrene (B[a]P) were investigated using a Salmonella/microsome assay. Tea extracts exhibited no inhibitory effects toward IQ and B[a]P in bio-antimutagenic assays, indicating that their antimutagenic activity is desmutagenic in nature. The mutagenicities of IQ and B[a]P decreased as the reaction periods of tea extracts with promutagens, S9 mix, or mutagen metabolites increased. The antimutagenicity of tea extracts toward IQ could be attributed (primarily) to an interaction between tea extracts and S9 mix. Apart from their interaction with S9 mix, tea extracts also exhibited antimutagenicity by markedly decreasing the mutagenicity of B[a]P metabolites. These results suggest that tea extracts: (1) inhibit the cytochrome P-450-mediated metabolism of IQ and B[a]P to their ultimate mutagenic metabolite form; and (2) interact with both promutagens and their metabolites in such a way as to reduce their mutagenic potentials. Therefore, the antimutagenic actions of tea extracts are due to a combination of the above distinctive mechanisms, and can vary with the type of mutagen under test.

Antioxidant effects of dopamine and related compounds.

The antioxidant and free radical scavenging effects of dopamine, noradrenaline, tyramine, and tyrosine were investigated and compared with alpha-tocopherol. The antioxidant effect of dopamine and its related compounds on peroxidation of linoleic acid were in the order of dopamine > alpha-tocopherol = tyramine > tyrosine > noradrenaline as measured by the thiocyanate method. These amine compounds had reducing power, and a scavenging effect on reactive oxygen species, i.e., superoxide anion and hydroxyl radical. The results for reducing power and scavenging effect of these amine compounds had a similar trend as their inhibition of linoleic acid peroxidation. The antioxidant activity of these amine compounds in soybean oil was also evaluated by the Rancimat method. The induction time to reach 100 meq/kg peroxide value (POV) of soybean oil for dopamine, alpha-tocopherol, tyramine, tyrosine, noradrenaline, and control were 9.0, 8.2, 8.0, 6.4, 4.6, and 4.3 h, respectively. The antioxidant efficacy of amine compounds seems to be correlated with the numbers of hydroxy groups and their position on the phenolic ring.