Decalepis hamiltonii roots boost antioxidant status of rat liver and brain

BACKGROUND: Roots of Decalepis hamiltonii are traditionally consumed as pickles and juice for their health benefits. We have earlier demonstrated the antioxidant property of the root extract and identified the constituent antioxidant molecules. RESULTS: This paper reports the effect of multiple‐dose (7, 15, and 30 days) treatment of Decalepis hamiltonii aqueous root extract (DHA) (50 and 100 mg kg^?1 body weight) on the antioxidant profile of rat liver and brain. Activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione‐S‐transferase (GST) were increased and glutathione content was elevated in both liver and brain, apart from reduction in the basal level of lipid peroxidation. DHA induced stronger antioxidant boost in brain by increasing the activities of SOD, CAT, and GPx compared to liver. CONCLUSION: As failure to grapple with oxidative stress is an important factor in the etiology of several diseases, DHA's effects on improvement of antioxidant status could provide a scientific justification for the health‐promoting properties attributed to it. Copyright © 2009 Society of Chemical Industry     

Antioxidant potential and radioprotective effect of soy isoflavone against gamma irradiation induced oxidative stress

The in vitro antioxidant potential and in vivo radioprotective ability of soy isoflavones was studied. Male Wistar rats were orally administered with soybean isoflavones (60 mg/kg) for 21 days followed by gamma irradiation exposure. Survival studies in rats exposed at 10 Gy and endogenous spleen colony forming unit assay (CFU) at 6.0 Gy were performed in order to find radioprotective and immunomodulatory nature of the compound. The rat liver post mitochondrial supernatant and erythrocytes were used to measure lipid peroxidation (LPO) and glutathione (GSH) content along with various antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT) and glutathione-S-transferase (GST) after gamma irradiation exposure at 2.0 Gy. Pretreatment with soy isoflavone, prior to gamma irradiation resulted in the increased survival rate of the animals as compared to irradiated group. CFU counts in the isoflavone treated group followed by gamma irradiation at 6 Gy were significantly high as compared to control and the irradiated group, showing immunomodulatory nature of the isoflavones. Pretreatment with isoflavones also significantly reduced the LPO, enhanced the activity of antioxidant enzymes and improved haematological and histological parameters. The present study suggests that supplementation with isoflavone has potent antioxidant activity and act as probable radioprotector against gamma radiation induced oxidative damage.     

大豆异黄酮和皂甙对扑热息痛诱导的小鼠急性肝损伤的保护作用

研究了大豆异黄酮和皂甙对扑热息痛(APAP)诱导的小鼠急性肝损伤的保护作用。将实验小鼠随机分为正常组、模型组、大豆异黄酮组、大豆皂甙组及联苯双酯组(阳性对照组)。每日给药1次,连续7 d。实验末期,腹腔注射APAP建立急性肝损伤模型,比色法检测血清谷丙转氨酶(ALT)、谷草转氨酶(AST)、碱性磷酸酶(ALP)、白蛋白(ALB)以及肝脏诱导型一氧化氮合酶(iNOS)、一氧化氮(NO)、过氧化脂质(LOOH)、丙二醛(MDA)、还原型谷胱甘肽(GSH)含量和过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)的活性。结果表明,大豆异黄酮和皂甙显著降低APAP诱发的急性肝损伤小鼠血清ALT、AST和ALP活性,增高血清ALB水平,降低肝iNOS活性和NO水平,减少肝LOOH和MDA含量,升高肝组织CAT、GPx、SOD活性和GSH水平。提示,大豆异黄酮和皂甙对APAP诱导的小鼠急性肝损伤具有保护作用,其机制可能与抗炎和抗氧化作用有关。     

The effect of selenium on antioxidant system in erythrocytes and liver of the carp (Cyprinus carpio L.)

The effect of selenium‐supplemented diet (sodium selenate and selenium yeast) on antioxidant in erthrocytes and liver of the carp (Cyprinus carpio L.) fingerlings was studied. With this goal, the activities of glutathione peroxidase (GSH‐Px), catalase (CAT), superoxide dismutase (SOD), glutathione reductase (GR) and glutathione‐S‐transferase (GST), as well as glutathione (GSH + GSSG) level, were determined. In the group supplemented with sodium selenate, no significant changes in the activity of the above enzymes were recorded in both the erythrocytes and in the liver, with the exception of GST activity that was significantly reduced in the plasma compared with the controls. Glutathione content was at the control level. In the group supplemented with selenium‐yeast, the activities of GSH‐Px, CAT, and SOD were significantly increased in erythrocytes, whereas GST activity and plasma content of GSH + GSSG were reduced compared with the controls. At the same time, the activities of hepatic SOD and GST were increased compared with the controls. These results demonstrate that organically bound selenium (selenium‐yeast) acts more efficiently on antioxidant system of the carp fingerlings than inorganic selenium salts.     

Content composition and antioxidant activity of isoflavones in commercial and homemade soymilk and tofu

BACKGROUND: Isoflavones, found in soymilk and tofu, are one of the phytochemicals in soy‐based products that may promote good health. Homemade tofu and various homemade soymilk samples were made using different soaking, grinding, and cooking methods. The homemade samples were compared to commercial tofu and soymilk for total isoflavone content and composition as well as their antioxidant capacity. All samples were freeze‐dried and extracted with a 58% acetonitrile solution which was subsequently used to determine the isoflavone content by reverse‐phase high‐performance liquid chromatography. The antioxidant activity of extracts was determined using a modified 2,2‐azino‐bis‐(3‐ethylbenzthiazoline‐6‐sulfonic acid) method and total antioxidant capacity was reported as ascorbic acid equivalents. RESULTS: The total isoflavone, aglycone, and antioxidant levels were significantly higher in homemade soymilk and tofu (1571 µg) than in commercial samples. Homemade soymilk made by the extended boiling method yielded the highest total isoflavone (2567 µg) and glucoside (1525 µg) content. A strong positive correlation was observed between the total isoflavone, aglycone conjugates, and genistein series concentration and antioxidant capacity of soymilk. CONCLUSION: Increased moist heating time yielded the highest concentration of total isoflavones as well as aglycone conjugates and the genistein series. Increasing the duration of boiling can increase the isoflavone content of both homemade and commercial soymilk and tofu. Copyright © 2007 Society of Chemical Industry     

Characterisation and comparison of phenols,flavonoids and isoflavones of soymilk and their correlations with antioxidant activity

To investigate the relationship between bioactive compounds and antioxidant property, total phenolic content (TPC), total flavonoid content (TFC), individual and total isoflavone content of soymilk and their correlations with oxygen‐radical‐absorbing capacity (ORAC), ferric reducing antioxidant power (FRAP) and 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging capacity values were evaluated and compared. Results showed that TPC, TFC, isoflavones (including concentration and profiles) and antioxidation activity significantly varied among ten tested soybean cultivars. Significant correlations were established between DPPH and TFC (r = 0.553, P < 0.01), DPPH and TPC (r = 0.753, P < 0.01), FRAP and TFC (r = 0.599, P < 0.01) and FRAP and TPC (r = 0.616, P < 0.01). Positive linear correlations were found between subtotal, total isoflavones and ORAC. Unlike other isoflavone monomers, aglycone isoflavones correlated positively with DPPH and FRAP significantly. DPPH well correlated with FRAP, whereas neither DPPH nor FRAP correlated with ORAC. TPC, TFC, individual and total isoflavone values are potentially useful for soymilk antioxidant activity assessment.     

Isoflavone profiles,phenol content,and antioxidant activity of soybean seeds as influenced by cultivar and growing location in Ohio

Isoflavone levels and isoflavone chemical composition in soybeans vary between planting locations although the exact factors which control isoflavone biosynthesis are unclear. We compared levels of 12 isoflavones in soybean seeds of six cultivars grown in four different locations in Ohio in 2002 as determined by high‐performance liquid chromatography. Antioxidant activity contained in plant‐based foods can improve food oxidative stability and phenolics and isoflavones have proven active in food systems. Radical scavenging activity was assessed using the 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH) radical. Total phenolics (TPCs) were determined by using Folin–Ciocalteu reagent. Total isoflavones (TIs) varied five‐fold (1573–7710 nmol g^?1) between seeds from the various location–cultivar combinations. One location (Wooster, Ohio) produced seeds containing half the isoflavones as the other locations tested apparently due to poor growing conditions. The cultivars could be divided into two groups based on TI, one having approximately 50% more isoflavones. Surprisingly, across the entire data set, with increasing TI, the proportion of isoflavones accounted for by the daidzein family increased due primarily to malonyl daidzin. DPPH scavenging did not differ significantly by location or cultivar (P > 0.05) and did not correlate with TPC or TI. Profiling soybean isoflavones could help elucidate how isoflavone biosynthesis is regulated and lead to better disease resistance of soybean crops and soy foods with greater health benefits. Copyright © 2007 Society of Chemical Industry     

酱油渣异黄酮抗氧化功效成分纯化研究

以酱油渣为原料,采用乙醇提取法提取酱油渣中大豆异黄酮,对提取条件进行了优化。比较了醇沉法、等电点沉淀法、浓缩离心法、正丁醇法、二氯甲烷法、乙酸乙酯萃取法等6种方法对异黄酮粗提物的纯化效果。通过高效液相鉴定了纯化产物的异黄酮单体组成,并采用邻苯三酚氧化法和DPPH法评价了异黄酮纯化物的体外抗氧化活性。结果表明：优化条件下提取的异黄酮粗提物中异黄酮质量分数为1.21%、提取率为（85.36±0.09）%。6种纯化方法中,浓缩离心法所得异黄酮产物中异黄酮纯度为7.75%,去除蛋白质效果最佳;二氯甲烷萃取法所得异黄酮产物中异黄酮纯度为27.74%,去除总糖和灰分效果最佳;两者联用后所得纯化产物的异黄酮纯度为44.88%,其主要由染料木素、大豆黄素和大豆素组成,质量分数分别为67.37%、9.33%、23.30%。在质量浓度为1 mg/mL时,异黄酮纯化物对超氧阴离子、DPPH自由基的清除率分别为67.65%、89.18%,显著高于异黄酮粗提物（P＜0.05）,其IC50分别为0.34、0.26 mg/mL,说明异黄酮纯化物具有一定的抗氧化活性,有望作为一种潜在的天然抗氧化剂应用于功能性食品中。     

Apple phlorizin supplementation attenuates oxidative stress in hamsters fed a high‐fat diet

Phlorizin from apple peel has been used as a nutrient for more than 100 years. The present study investigated the effects of phlorizin on the antioxidant capacity and the antioxidative mechanisms in hamsters fed high‐fat diet supplemented with phlorizin (0.3, 0.6, and 0.9%). Results showed that phlorizin increased the antioxidant enzyme activities and reduced the malondialdehyde content in plasma, liver, heart, and kidney that might arise from the higher mRNA levels of CuZn‐superoxide dismutase, Mn‐superoxide dismutase (Mn‐SOD), catalase, glutathione peroxidase, nuclear factor erythroid 2‐related factor 2‐like (Nrf2), and the protein expression of Mn‐SOD (p < .05). Diet supplemented with phlorizin also significantly decreased the total cholesterol and triglycerides levels in plasma. The present study demonstrated that phlorizin might reduce lipid peroxidation and protect against cardiovascular issues in vivo.

Practical applications

Phlorizin, from apple peel, has been used as a nutrient for over 100 years. To date, despite extensive research on phlorizin, a report on its effect on lipid peroxidation, the antioxidant system in plasma, heart, liver, and kidney of hamsters fed high‐fat diet is yet lacking. This report demonstrates that phlorizin can reduce lipid peroxidation and exert a protective effect on cardiovascular issues in vivo, which is valuable in the rational utilization of phlorizin in functional foods.     

The role of two putative nitroreductases,Frm2p and Hbn1p,in the oxidative stress response in Saccharomyces cerevisiae

The nitroreductase family is comprised of a group of FMN‐ or FAD‐dependent enzymes that are able to metabolize nitrosubstituted compounds using the reducing power of NAD(P)H. These nitroreductases can be found in bacterial species and, to a lesser extent, in eukaryotes. There is little information on the biochemical functions of nitroreductases. Some studies suggest their possible involvement in the oxidative stress response. In the yeast Saccharomyces cerevisiae, two nitroreductase proteins, Frm2p and Hbn1p, have been described. While Frm2p appears to act in the lipid signalling pathway, the function of Hbn1p is completely unknown. In order to elucidate the functions of Frm2p and Hbn1p, we evaluated the sensitivity of yeast strains, proficient and deficient in both oxidative stress proteins, for respiratory competence, antioxidant‐enzyme activities, intracellular reactive oxygen species (ROS) production and lipid peroxidation. We found reduced basal activity of superoxide dismutase (SOD), ROS production, lipid peroxidation and petite induction and higher sensitivity to 4‐nitroquinoline‐oxide (4‐NQO) and N‐nitrosodiethylamine (NDEA), as well as higher basal activity of catalase (CAT) and glutathione peroxidase (GPx) and reduced glutathione (GSH) content in the single and double mutant strains frm2Δ and frm2Δ hbn1Δ. These strains exhibited less ROS accumulation and lipid peroxidation when exposed to peroxides, H₂O₂ and t‐BOOH. In summary, the Frm1p and Hbn1p nitroreductases influence the response to oxidative stress in S. cerevisae yeast by modulating the GSH contents and antioxidant enzymatic activities, such as SOD, CAT and GPx. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of trypsin inhibitor on plasma antioxidant activity and lipid levels in mice from sweet potato roots

BACKGROUND: Several inflammatory diseases are thought to be related to oxidative injury and reactive oxygen species have been proposed as important causative agents of heart disease and ageing. This study was designed to investigate the effects of sweet potato trypsin inhibitor (SPTI) on antioxidant enzymes, lipid peroxidation and lipid profiles in mice. RESULTS: Twenty mice were randomly divided into four groups and fed with TI (10, 50 and 100 mg kg^?1 BW) as treatment and with saline as a control in addition to regular diets. After 35 days, Trolox equivalent antioxidant capacity (TEAC), triglyceride (TG) and cholesterol levels in plasma and superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx), thiobarbituric acid reactive substances (TBARS) in liver were measured. Serum from the group that had received the the highest oral dose of SPTI (100 mg kg^?1 BW) had the highest total antioxidant activity (expressed as 3.59 ± 0.237 mmol L^?1 TEAC). The SOD, catalase and GPx activity of SPTI groups were significantly increased compared with the control group. Malondialdehyde (MDA) was significantly lower in all experimental groups compared with the control one. No significant differences in the concentration of low‐density lipoprotein (LDL)‐cholesterol was found, but high density lipoprotein (HDL)‐cholesterol, triglyceride (TG) and total cholesterol tended to decrease. CONCLUSION: This study showed that the oral intake of SPTI in mice may trigger inflammatory responses which result in an increase in antioxidant enzyme activities, and a decrease in MDA, TG and total cholesterol, which are known risk factors of inflammatory and heart disease. Copyright © 2008 Society of Chemical Industry     

INFLUENCE OF HEAT TREATMENT AND GRAIN GERMINATION ON THE ISOFLAVONE PROFILE OF SOY MILK

Soy foods have attracted much attention for their possible effects on human health because of their phytochemical content, mainly isoflavones. Twelve forms of isoflavones have been identified in soybeans and soy products. Technological processes like heat treatment or fermentation can change the isoflavone profile of soy products. In this study, the effects of heat treatment and grain germination on isoflavone profile of soy milk prepared from BRS 213 soybean variety were evaluated. Isoflavone forms were separated and quantified by reversed‐phase high‐performance liquid chromatography. Heat treatment by autoclaving for 5 min did not affect the total isoflavone content, but led to a 90% decrease in malonyl forms, whereas β‐glycosides increased by 70%. Autoclaving for 15 min led to a 20% loss of total isoflavones. Germination for 3 days did not change the total isoflavone content, but changed the distribution profile (15% increase of malonyl forms and 30% decrease of β‐glycosides). Germination for 7 days increased the bioavailability of aglycone isoflavones in soy milk by seven times.     

Effects of a mixed koji culture of Aspergillus oryzae HG‐26 and Aspergillus niger HG‐35 on the levels of enzymes,antioxidants and phenolic compounds in soy sauce during the fermentation process

Soy sauce contains a number of bioactive components, which have been shown to possess strong antioxidative properties. The objective of this study was to compare the enzyme activities, antioxidant activity and phenolic compounds content of soy sauces prepared from a mixed koji (SSAON, inoculated with Aspergillus oryzae HG‐26 and Aspergillus niger HG‐35), with those of soy sauces made from a koji culture containing only Aspergillus oryzae HG‐26 koji (SSAO). The total phenolic content (TPC), total flavonoid content (TFC), content of three isoflavone aglycones (daizein, glycitein and genistein) and the antioxidant activity of the SSAON were found to be higher than those of the SSAO during moromi fermentation. In addition, they showed strong positive correlations with the antioxidant potential of the soy sauce. This study has demonstrated the potential of a mixed‐culture koji, based upon A. orzyae and A. niger, for the production of soy sauce with an increased level of bioactive components.     

Preparation and characterisation of soya milk enriched with isoflavone aglycone fermented by lactic acid bacteria combined with hydrothermal cooking pretreatment

A fermented soya milk (FSM) enriched with isoflavone aglycone (FSM‐SPIA) was prepared from heated soya protein isolate (SPI)‐isoflavone complex. After 48 h of fermentation, FSM‐SPIA contained higher contents of living bacteria, free amino acids and aglycone compared with the FSM of SPI (FSM‐SPI) and the FSM of SPI‐isoflavone complex (FSM‐Mix). In the in‐vitro digestion experiment, FSM‐SPIA showed higher antioxidant capacity and isoflavones (ISO) bioavailability than FSM‐SPI and FSM‐Mix. This was likely due to the soya milk containing a higher level of amino acid, peptides and the presence of soya bean isoflavone. The improved protein digestibility, the interaction and binding ability between proteins and ISO may affect the properties of the protein and the fermented products. The FSM enriched with isoflavone aglycone can be used as a functional fermented drink, as well as an auxiliary food for menopausal women during a specific pathological period.     

Preparation and characterisation of glyceollin‐enriched soya bean protein using solid‐state fermentation

Glyceollins, stress‐induced phytoalexins from parent soya bean isoflavones, were elicited with Aspergillus oryzae. This solid‐state fermentation facilitated the conversion of isoflavone glycosides into aglycones and glyceollins, which could mainly enrich in soya bean protein isolate (SPI) during protein preparation due to protein–polyphenol interactions. Glyceollin‐enriched SPI exhibited less flavour volatiles, higher solubility, lower whiteness and higher antioxidant activity than unfermented SPI. Fermented SPI was more easily to be digested during in vitro pepsin–trypsin digestion. This may be attributed to partial degradation of protein, especially α′ and α subunits of β‐conglycinin and acidic subunit of glycinin. The antioxidant activity of digestive products derived from fermented SPI was obviously enhanced with increasing digestion time due to simultaneous release of antioxidant peptides and glyceollins involved in the interior of protein molecule. These results suggest an effective technique for producing a nutrient‐enhanced SPI as novel functional ingredients applied in food industry.     

Urinary isoflavone excretion in Korean adults: comparisons of fermented soybean paste and unfermented soy flour

BACKGROUND: This study compared the 24 h urinary excretion of isoflavone algycones after the consumption of fermented soybean paste or unfermented soy flour in a population of healthy Koreans (four males and five females). An equivalent amount (20 mg) of total isoflavone was consumed as either 52 g of soybean paste or 12.2 g of soy flour in a randomised, crossover trial consisting of two single‐time‐point feedings and having 3 day run‐in and washout periods between feedings. RESULTS: Analysis of starting materials indicated that daidzein (1.4%) and genistein (1.4%) constituted a smaller proportion of the total isoflavones in soy flour as compared with soybean paste (55.3% daidzein and 45.7% genistein). Free and glycosidic forms of isoflavones differed significantly between the two soy products. Levels of β‐glycosides as well as total glycosides (β‐glycosides, malonyl and acetyl forms) were two‐fold higher in soy flour as compared with soybean paste. Malonyl forms predominated in soy flour. CONCLUSIONS: The consumption of soybean paste resulted in significantly higher urinary excretion of both daidzein and genistein as compared with soy flour (P < 0.05 and P < 0.01 respectively). Copyright © 2007 Society of Chemical Industry     

Cellular DNA breakage by soy isoflavone genistein and its methylated structural analogue biochanin A

Epidemiological studies have indicated that populations with high isoflavone intake through soy consumption have lower rates of breast, prostate, and colon cancer. The isoflavone polyphenol genistein in soybean is considered to be a potent chemopreventive agent against cancer. In order to explore the chemical basis of chemopreventive activity of genistein, in this paper we have examined the structure–activity relationship between genistein and its structural analogue biochanin A. We show that both genistein and its methylated derivative biochanin A are able to mobilize nuclear copper in human lymphocyte, leading to degradation of cellular DNA. However, the relative rate of DNA breakage was greater in the case of genistein. Further, the cellular DNA degradation was inhibited by copper chelator (neocuproine/bathocuproine) but not by compounds that specifically bind iron and zinc (desferrioxamine mesylate and histidine, respectively). We also compared the antioxidant activity of the two isoflavones against tert‐butylhydroperoxide‐induced oxidative breakage in lymphocytes. Again genistein was found to be more effective than biochanin A in providing protection against oxidative stress induced by tert‐butylhydroperoxide. It would therefore appear that the structural features of isoflavones that are important for antioxidant properties are also the ones that contribute to their pro‐oxidant action through a mechanism that involves redox cycling of chromatin‐bound nuclear copper.     

Antioxidant balance after long-term consumption of standard diets including bread crust glycated compounds by adult rats

The objective of the present study was to evaluate the in vivo uptake of antioxidant capacity (AC) in rats fed on diets containing commonly consumed MRPs obtained from bread crust (BC) at long-term. Additionally we focused on understanding the effects of those compounds on the oxidative status of these animals. The global antioxidant response of the diets was measured. During 88 days, rats were fed control diet or diets containing BC or its soluble high molecular weight, soluble low molecular weight or insoluble fractions (BC, HMW, LMW and insoluble diets, respectively). In the final week, faeces from different dietary treatments were collected to determine the AC still retained in it and then calculate the uptake efficiency of AC. Animals were sacrificed and the liver and biceps brachii muscle were removed to investigate catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) levels. The addition of BC or its derivatives in the diet led to a significantly higher AC excreted with the faeces and to a lower uptake rate (around 90% in these groups vs. 98% in the control group). The muscle and liver showed different oxidative status after consumption of experimental diets. The muscle evidenced certain oxidative damage due to the BC consumption, more pronounced when the isolated fractions were ingested. However, the BC diet, but not the rest, induced a positive effect on the antioxidant defence in the liver, the key organ for xenobiotic metabolism, with increases in the CAT and GPx activities as well as the GSH stock (56, 20 and 14% with respect to the control group, respectively). The discordance found between the antioxidant status of muscle and antioxidant status of liver highlights the importance of considering several tissues to establish the effect of glycated compounds on the redox balance in an organism.     

Effect of Lactic Acid Fermentation on Enrichment of Antioxidant Properties and Bioactive Isoflavones in Soybean

ABSTRACT: The antioxidant properties of 80% ethanolic extracts from soybean obtained with lactic acid fermentation using ABTS•⁺ [2,2'-azinobis (3-ethylbenzothiazoline-6-sulphonicacid) diammonium salt] free radical decolorization assay and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging assay were measured, and the relationship between the observed antioxidant properties and the compositional changes in the isoflavone isomers was evaluated. Fermentation of soybean with 4 bacterial strains producing β-glucosidase for 48 h at 37°C— Lactobacillus plantarum KFRI 00144, Lactobacillus delbrueckii subsp. latisKFRI01181, Bifidobacteriathermophilum KFRI00748, and Bifidobacteria breve K-101—resulted in a significant increas (P < 0.05) in the antioxidant capacity expressed as Trolox equivalent antioxidant capacity (TEAC) (mM) and % scavenging activity. The significant bioconversion (P < 0.001) of the isoflavone glucosides (daidzin + genistin) into their responding bioactive aglycones (daidzein + genistein) during soy fermentation was observed. There was a good linear correlation between the concentration of isoflavone aglycones and the scavenging activity of ABTS ( R = 0.9045) assay, and DPPH ( R = 0.8299) assay in each extract. Among each extract, B. thermophilum KFRI 00748 showed a particularly high antioxidant activity (19.8 mM TEAC) and increased by 4.1 times compared with that of the control (4.8 mM TEAC), which fermented without strains. These results indicated that fermented soybean could be regarded as a potent antioxidant and radical scavenging dietary source due to their remarkable content of bioactive isoflavones.