Antioxidative Potential of Cheonggukjang Prepared with Soybean Varieties with Different Levels of Isoflavones and Anthocyanins

Abstract

Cheonggukjang is a popular Korean traditional fermented soy food manufactured by fermenting steamed soybeans with Bacillus species. We examined the antioxidative activity of methanolic extract of cheonggukjang prepared with different strains. The extract of cheonggukjang prepared with B. amyloliquefaciens showed stronger antioxidative activity than those of other strains. In order to investigate in vivo antioxidative effect of cheonggukjang prepared by fermenting four varieties of soybean (Aga No 3, Aga No 4, TaeGwang, Ilpoom Black No 1) containing different levels of isoflavones and anthocyanins with B. amyloliquefaciens, eighty mice were divided into 8 groups including control, CCl4‐treated group, steamed soybean group, four cheonggukjang + CCl4 groups, and vitamin E + CCl4 group. Mice were fed experimental diet containing 0 or 30% cheonggukjang or vitamin E (2000 IU/kg) for 14 days, followed by injection with CCl4 (day 1), and sacrificed at 14th day after beginning of experiment. The hepatic levels of antioxidant and detoxification enzymes including heme‐oxigenase‐1 (HO‐1), CYP450s in liver collected from experimental groups were compared using western blot. The markers for oxidative damage such as MDA and 8‐OH‐dG were also assayed for tissues collected from experimental groups. In conclusion, anthocyanins in soy but not isoflavones appear to make major contribution to antioxidant activity of soy.