Antioxidative activity and safety of the 50% ethanolic extract from red bean fermented by Bacillus subtilis IMR-NK1

This study aimed at evaluating the antioxidative activities and the safety of 50% ethanolic extract from red bean fermented by Bacillus subtillis IMR-NK1. The antioxidative activities, including alpha,alpha-diphenyl-beta-picryl-hydrazyl (DPPH) radicals scavenging effects, Fe2+-chelating ability, and reducing power, were studied in vitro. It was found that the antioxidative activity increased with the concentrations of the extract to a certain extent and then leveled off as the concentration further increased. As compared to the commercial antioxidants, the fermented red bean extract showed less scavenging effect on the DPPH radical and reducing power than a-tocopherol and BHT, but better Fe2+-chelating ability. No mutagenicity or toxicity effect toward all tester strains was found in the 50% ethanolic extract of fermented red bean by means of the Ames test. The results suggested that the 50% ethanolic extract was safe in genotoxicity.