Modulation of genotoxicity and DNA repair by plant monoterpenes camphor, eucalyptol and thujone in Escherichia coli and mammalian cells.

The aim of this work was to examine the antigenotoxic potential of plant monoterpenes: camphor, eucalyptol and thujone in prokaryotic and eukaryotic cells and to elucidate their effect on DNA repair. We compared the effect of monoterpenes on spontaneous, UV- and 4NQO-induced mutagenesis in Escherichia coli K12 repair proficient, and MMR and NER deficient strains. Positive controls tannic acid and vanillin were included in bacterial tests. We also examined protective effect of monoterpenes against 4NQO-induced genotoxicity in Vero cell line by alkaline comet assay. The results obtained in repair proficient strain indicated antimutagenic potential of monoterpenes against UV- and 4NQO-induced mutagenesis, which was diminished with NER deficiency. Camphor and eucalyptol maintained UV-induced SOS response longer than in controls, while thujone decreased SOS response and reduced general protein synthesis and the growth rate. The three monoterpenes increased spontaneous and UV-induced recombination in recA730 and camphor additionally in recA(+) cells. Incubation of 4NQO-pretreated Vero cells with monoterpenes resulted in significant reduction of tail moment. However, higher concentrations of monoterpenes induced DNA strand breaks. Obtained results indicate that by making a small amount of DNA lesions camphor, eucalyptol and thujone can stimulate error-free DNA repair processes and act as bioantimutagens.