Suppression of chemical mutagen-induced SOS response by allylbenzen from Asiasarum heterotropoides in the Salmonella typhimurium TA1535/PSK1002 umu test.

A methanol extract from Asiasarum heterotropoides showed a suppressive effect of the SOS-including activity on the mutagen 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) in the Salmonella typhimurium TA1535/pSK1002 umu test. The methanol extract was re-extracted with chloroform, butanol, and water. The chloroform fraction showed a suppressive effect. Suppressive compounds in the chloroform fraction were isolated by silica gel column chromatography and identified as methyleugenol (1), elemicin (2), and gamma-asaron (3) by GC/MS, IR, and 1H- and 13C-NMR spectroscopy. These compounds suppressed the MeIQ-induced SOS response in the umu test. Gene expression was suppressed 52.2, 61.8, and 71.6% at a concentration of 0.1 mM, respectively. The ID50 values (50% inhibition dose) of these compounds were 0.080, 0.028, and 0.013 mM, respectively. On the other hand, Compounds 1-3 showed weak suppressive effect of the SOS-inducing activity on activated MeIQ. These results indicate that the inhibition of the SOS-inducing activity on MeIQ, which was caused by Compound 1-3 was due to the inhibition of metabolic activity by S9.