Antimutagenic effects of dehydrozingerone and its analogs on UV-induced mutagenesis in Escherichia coli.

Antimutagenic activities of dehydrozingerone, benzalacetone and its analogs substituted with the hydroxyl, methoxyl or methyl group on the benzene ring were investigated by the post-treatment for UV-induced mutagenesis in Escherichia coli WP2s (uvrA). In this assay, dehydrozingerone was a poor antimutagen. Among the test compounds except for 2-hydroxybenzalacetone, benzalacetone was the most strong antimutagen, showing that the ring substitutions decrease the antimutagenic activities. 2-Hydroxybenzalacetone was, however, more effective than benzalacetone. The antimutagenicity of 2-hydroxybenzalacetone might be dependent on the property that is known to associate inter-molecularly by hydrogen bonding between the hydroxyl group and the carbonyl group. The effects of the side chain, single, double or triple bond and its adjacent carbonyl group, were further investigated using benzylacetone with saturated carbonyl chain, benzalacetone with double-bonded carbonyl chain, 4-phenyl-3-butyn-2-one with triple-bonded carbonyl chain and trans-beta-methyl styrene with only double bond. Benzalacetone and 4-phenyl-3-butyn-2-one suppressed the UV-induced mutagenesis, but benzylacetone and trans-beta-methyl styrene scarcely inhibited the mutagenesis: an alpha, beta-double or triple-bonded carbonyl system was necessary for the antimutagenic activity. 4-Phenyl-3-butyn-2-one showed the potent antimutagenicity at one order lower concentrations than that of benzalacetone. Benzalacetone, 2-hydroxybenzalacetone and 4-phenyl-3-butyn-2-one that were effective on the UV-induced mutagenesis also decreased the gamma-induced mutagenesis in Salmonella typhimurium TA2638.