Antimutagenic activity of isoflavone from Pueraria lobata

A methanol extract from Pueraria lobata showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK100 2 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuram ide). The methanol extract from P. lobata was re-extracted with hexane, dic hloromethane, ethyl acetate, butanol, and water, respectively. A suppressiv e compound in the dichloromethane and ethyl acetate extract fractions was i solated by SiO2 column chromatography and identified as tectorigenin (1) by EI-MS and H-1 and C-13 NMR spectroscopy Compound 1 and its methylated deri vative [7,4'-di-O-methyltectorigenin (2)] had the suppressive effects on um u gene expression of the SOS response in Salmonella typhimurium. TA1535/pSK 1002 against furylfuramide, 4-nitroquinoline-1-oxide, N-methyl-N'-nitrosogu anidine, and activated Trp-P-1, which do not require live metabolic activat ion by S9. These compounds also showed suppression of SOS-inducing activity against Trp-P-1 and AfB(1), which requires liver metabolizing enzymes. In addition to the antimutagenic activities of these compounds against furylfu ramide, Trp-P-1 and activated Trp-P-1 were also assayed by an Ames test usi ng S. typhimurium TA100.