Simple SummaryThe aim of the present study was to evaluate, for the first time, the genotoxic and antigenotoxic potential of thymol on the honey bee continuous cell line AmE-711 using the Comet assay. Thymol did not show antigenotoxic effect on honey bee cells in any of the tested concentrations (10, 100, and 1000 μg/mL). Two concentrations (100 and 1000 μg/mL) expressed genotoxic effects on cultured honey bee cells, thus suggesting the careful application of thymol in beekeeping practice to avoid possible negative effects on honey bees.AbstractThymol is a natural essential oil derived from the plantThymus vulgarisL. It is known to be beneficial for human and animal health and has been used in beekeeping practice againstVarroamite for years. In this study, the genotoxic and antigenotoxic potential of thymol were evaluated on the honey bee (Apis melliferaL.) continuous cell line AmE-711 for the first time. Using the Comet assay, three increasing concentrations (10, 100, and 1000 µg/mL) of thymol were tested. Negative control (non-treated cells) and positive control (cells treated with 100 µM H2O2) were also included. The absence of thymol cytotoxicity was confirmed with the Trypan blue exclusion test. Thymol in the concentration of 10 µg/mL did not increase DNA damage in AmE-711 honey bee cells, while 100 and 1000 µg/mL concentrations showed genotoxic effects. For testing the antigenotoxic effect, all concentrations of thymol were mixed and incubated with H2O2. The antigenotoxic effect against was absent at all concentrations (10, 100, 1000 μg/mL) tested. Moreover, thymol enhanced the H2O2-induced DNA migration in the Comet assay. The obtained results indicate genotoxic effects of thymol on cultured honey bee cells suggesting its careful application in beekeeping practice to avoid possible negative effects on honey bees.