Antimutagenic Activity of (+)-β-Eudesmol and Paeonol from Dioscorea japonica

A methanol extract from Dioscorea japonica showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The methanol extract from D. japonica was re-extracted with dichloromethane, n -butanol, and water, respectively. The suppressive compounds in the dichloromethane extract fraction were isolated by SiO 2 column chromatography and identified as (+)-β-eudesmol and 2-hydroxy-4-methoxyacetophenone (paeonol) by EI-MS and 1 H and 13 C NMR spectroscopy. (+)-β-Eudesmol suppressed the SOS-inducing activity of furylfuramide in the umu test. Gene expression was suppressed 80% at <0.18 μmol/mL, and the ID 50 value was 0.09 μmol/mL. Paeonol also suppressed the SOS-inducing activity of furylfuramide in the umu test. Gene expression was suppressed 60% at <1.2 μmol/mL, and the ID 50 value was 0.99 μmol/mL. (+)-β-Eudesmol and paeonol were assayed with the mutagen 3-amino-1,4-dimethyl-5 H -pyrido[4,3- b ]indole (Trp-P-1), which requires liver metabolizing enzymes, and showed suppressive effects on the SOS induction of the mutagen. (+)-β-Eudesmol suppressed gene expression 48% at <0.18 μmol/mL. Paeonol suppressed gene expression 76% at <1.2 μmol/mL, and the ID 50 was 0.41 μmol/mL. The antimutagenic activities of these compounds against furylfuramide and Trp-P-1 were tested by an Ames test using S . typhimurium TA100, which indicated that these compounds showed antimutagenic activity.