Antioxidant and antigenotoxic activities of Korean fermented soybean

This study was aimed at evaluating the antioxidative and antigenotoxic activities of Korean fermented soybean (Chungkookjang) in vitro and in vivo. The 100% ethanol extract of Chungkookjang (CKJ) inhibited the generation of 1,1-diphenyl-2-picryl hydrazine (DPPH) radicals, and had an inhibitory effect on LDL oxidation. CKJ and its constituents (genistein and daidzein) also inhibited H2O2-induced DNA damage from NIH/3T3 fibroblasts. Furthermore, they showed the cytoprotective effects against H2O2-induced cell death. In vivo study also demonstrated that an oral administration of CKJ extract (800 mg/kg/day) for 2 weeks potently inhibited the formation of malondialdehyde, the damage of DNA and the formation of micronucleated reticulocytes in KBrO3-treated mice. The well-known antioxidants, trolox and vitamin C, also showed the potent inhibition on these parameters. All these results indicate that CKJ extract may be a useful antigenotoxic antioxidant by scavenging free radicals, inhibiting lipid peroxidation and protecting against oxidative DNA damage. The isoflavones, genistein and daidzein, may contribute to these biological effects of CKJ extract at least in part. Korean fermented soybean (Chungkookjang) is suggested to be a promising functional food witch can prevent oxidative stress.