Effect of metabolic transformation of monoterpenes on antimutagenic potential in bacterial tests

The effect of metabolic transformation of the monoterpenes Linalool (Lin), Myrcene (Myr) and Eucalyptol (Euc) was evaluated on their antimutagenic potential against t-butyl hydroperoxide (t-BOOH) and 2-nitropropane (2NP) in E. coli WP2 and in S. typhimurium reversion assays, respectively. Spontaneous mutagenesis was also monitored in both assays. Mammalian metabolic transformation was provided by rat liver microsomes (S9 fraction). None of the monoterpenes was mutagenic, either with or without S9. Results obtained without S9 showed the antimutagenic potential of Lin against t-BOOH, of Myr against both t-BOOH and 2NP, and of Euc against spontaneous and mutagenesis induced with both mutagens. Mammalian enzymes significantly reduced the antimutagenic effect of Lin, completely diminished the antimutagenic effect of Myr, but did not alter the antimutagenic effect of Euc. Considering the results, metabolic transformation by host enzymes could significantly influence antimutagenic potential and should be included in antimutagenicity studies in prokaryotic assays. [Acknowledgments. This research was supported by the Ministry of Education and Science of Republic of Serbia, Project No. 172058.]