Antimutagenic activity of flavonoids from Sozuku.

Pinocembrin (1) and cardamonin (2) from Sozuku showed a suppressive effect on umu gene expression of SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen furylfuramide. Compounds 1 and 2 suppressed 52% and 36% of SOS-inducing activity at a concentration of 0.20 μmol/mL. The ID value of 1 was 0.18 μmol/mL. These compounds showed the suppression of 2-amino-3,4-dimethylimidazo-[4,5-f]quinolone (MeIQ) and UV irradiation-induced SOS response. Pinostrobin (3) and 5,7-dimethoxyflavanone (4), methyl ethers of 1, showed similar activity to 1 against MeIQ-induced SOS response, but that of furylfuramide and UV irradiation were decreased. On the other hand, compounds 1-4 did not show the suppression of activated MeIQ-induced SOS response. Furthermore, compounds 1-4 showed potent antimutagenic activity against MeIQ mutagenesis in Ames test using the S. typhimurium TA100 and TA98 strains.