Antimutagenic activity of flavonoids from Pogostemon cablin.

A methanol extract from Pogostemon cablin showed a suppressive effect on umu gene expression of SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract was re-extracted with hexane, dichloromethane, butanol, and water. A dichloromethane fraction showed a suppressive effect. Suppressive compounds against furylfuramide in the dichloromethane fraction were isolated by SiO(2) column chromatography and identified as 7,4'-di-O-methyleriodictyol (1), 7, 3',4'-tri-O-methyleriodictyol (2), and 3,7,4'-tri-O-methylkaempferol (3). In addition, three flavonoids, ombuine (4), pachypodol (5), and kumatakenin (6), were isolated and identified from the dichrolomethane fraction. Compounds 1 and 3 suppressed >50% of the SOS-inducing activity at <0.6 micromol/mL, and the ID(50) values of both compounds were 0.25 micromol/mL. Compound 2 showed a weakly suppressive effect (17%) at a concentration of 0.6 micromol/mL, and compounds 4-6 did not. These compounds were also assayed with 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), which requires liver metabolizing enzymes. Compounds 3-6 suppressed >80% of the SOS-inducing activity of Trp-P-1 at <0.06 micromol/mL, and compounds 1 and 2 suppressed 87 and 63% at a concentration of 0.3 micromol/mL. In addition, these compounds were assayed with activated Trp-P-1, and the suppressed effects of these compounds were further decreased when compared to Trp-P-1. The antimutagenic activities of these compounds against furylfuramide, Trp-P-1, and activated Trp-P-1 were assayed by the Ames test using S. typhimurium TA100.