The effects of thymol on sister chromatid exchange, chromosome aberration and micronucleus formation in human lymphocytes

In the present study, the genotoxic and cytotoxic effects of thymol were investigated in human peripheral lymphocytes treated with 25, 50, 75 and 100 ?g/ml concentrations of thymol for 24 and 48 hours treatment periods. The genotoxicity of thymol was investigated by studying sister chromatid exchange (SCE), chromosome aberration (CA) and micronucleus (MN) tests. Nucleear division index (NDI), replication index (RI) and mitotic index (MI) were also calculated to determine the cytotoxicity of thymol. Thymol significantly increased the mean SCE especially at the lower concentrations. Thymol also increased the mean SCE at the highest concentrations without statistical significant. On the other hand, thymol induced both the structural CA and frequency of MN at all concentrations. However, thymol could not induce the numerical CA. There were no dose-dependent effects between mean SCE, structural CA, frequency of MN and concentrations of thymol. Thymol dosedependently decreased the NDI for two treatment periods. Thymol decreased the RI for 24 hours treatment time without statistical significance. However, decreased the RI for 48 hours treatment time in a dose-dependent manner. Thymol also decreased the MI especially at the higher concentrations. However, no dose-dependent effect was observed. Key Words: Thymol, human peripheral lymphocytes, sister chromatid Exchange, chromosome aberration, micronucleus.