The effect of quercetin on the mutagenicity of 2-acetylaminofluorene and benzo[alpha]pyrene in Salmonella typhimurium strains.

The comutagenic and desmutagenic effect of quercetin on the mutagenicity of typical mutagens e.g. 2-acetylaminofluorene (AAF), 4-nitroquinoline-1-oxide (4NQO) and benzo[alpha]pyrene (B[a]P), in Salmonella typhimurium TA98, TA100 and TA98/1,8 DNP6 were examined. In the mixed application of AAF with quercetin in the presence of mammalian metabolic activation system (S9 mix), the numbers of revertants in TA98 increased by as much 2.2-5.0-fold compared with the sum of those in the separate applications of AAF and quercetin. A 1.4-2.7-fold increase was observed in TA100. Quercetin did not affect the mutagenicity of 4NQO, and depressed that of B[a]P. Dose-response curves for mutagenicity of quercetin with or without AAF (5 micrograms/plate) were examined. The results suggest that quercetin, present in a molarity of up to 1.5 times that of AAF, is apparently effective in enhancing the mutagenicity of AAF, because a linear dose-response curve was observed in the range of 0-5 micrograms/plate quercetin with AAF although quercetin alone was not mutagenic in the same range. Dose-response curves for mutagenicity of quercetin with or without 5 micrograms/plate B[a]P did not increase compared with that for quercetin alone. The mutagenicity of the mixed application of B[a]P with quercetin was reduced to about 60% of the sum of separate application at doses ranging from 25 to 100 micrograms/plate of quercetin. Since enhancement and depression of mutagenicity by quercetin were observed for indirect mutagens, AAF and B[a]P, respectively, in the presence of S9 mix, quercetin may affect the metabolic pathway of these mutagens.