Antimutagenic activity of Aspergillus awamori-fermented black soybean response to simulated digestive juice treatments and its antimutagenic mechanisms

Aspergillus awamori-fermented black soybeans, a potential healthy food ingredient, possess antimutagenicity against 4-nitroquinoline-N-oxide (4-NQO); a direct mutagen and benzo[a]pyrene (B[a]P; an indirect mutagen). Results of this study revealed that antimutagenic, desmutagenic, and blocking effects all contributed to the antimutagenicity of the methanol of fermented black soybean. However, the desmutagenic effect of the fermented black soybean extract on B[a]P is not caused by the interaction of intact B[a]P or S9 mixture with the extract. Instead, it is due to the interaction of B[a]P metabolites with the antimutagenic factors in the extract. Exposure to simulated gastric juice (pH 1.2) for 30 min or intestinal juice for 2 h resulted in a reduced antimutagenicity of fermented black soybean extract. Nevertheless, the simulated gastric juice treated-fermented black soybean extracts and the simulated intestinal juice treated-fermented black soybean extracts still possessed a considerable antimutagenic effect against 4-NQO and B[a]P.