Hydrophilic antimutagens in fermented defatted soybeans with Neurospora intermedia (D-oncom)

The author has previously reported on the higher antioxidative activity In vivo of defatted soybean oncom (D-oncom), fermented defatted soybeans with Neurospora inter-media, in comparison with that of defatted soybeans (DSB). In this paper. the hydrophilic antimutagenicity of D-oncom against N-nitrosodimethylamine (NDMA) was investigated. Water-extract of D-oncom had a stronger antimutagenicity than that of DSB. The main anti-mutagenic fraction of D-oncom was anionic, and stable against heating at 37 deg C. Its antimu-tagenicity was about one sixth of that of ascorbic acid. Actually the fraction scavenged superoxide anions. Therefore, the antimutagenicity of D-oncom against NDMA might be involved in the reduction of oxidative stress by scavenging superoxide anions. Nonetheless the main antimutagenic fraction was not polyphenol, peptide nor nucleotide, its molecular weight being distributed about 5.000-12,500.