Abstract

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous contaminants with a high octanol-water partition coefficient (kow) and are persistent in the environment. PAHs have various modes of action including mutagenicity, carcinogenicity, and teratogenicity. The mutagenic sensitivity to PAHs of single-cell gel electrophoresis (Comet assay) was compared with the Ames reversion Salmonella experiment (using Salmonella typhimurium TA98, TA100 and TA102) were with and without an exogenous metabolic activation system (S9 mix). S. typhimurium strains TA98, TA100 and TA102 treated with 4 and 40 µM of benzo[a]pyrene, 2-methylnaphthalene, and phenazine with and without S9 mix. Similarly, Caco-2 cells were treated with 5, 10, 20 and 40 µM of the chosen PAHs in the presence or absence of S9 mix. Even at the lowest treatment concentration (4 µM), benzo[a]pyrene, 2-methylnaphthalene and phenazine, significantly (p < 0.05) increased the number of revertant colonies of S. typhimurium TA98, TA100, and TA102 with S9 mix only. Similarly, the chosen PAHs significantly (p < 0.05) increased the tail moments of Caco-2 cells at the lowest treatment concentration (5 µM), resulting in decreased cell growth and viability as in the case of 2-methylnaphthalene. However, DNA damage to Caco-2 cells was not dependent on the S9 mix. The comet assay exhibits a comparable and more sensitive reaction to the tested PAHs than the Ames assay due to the inherent CYP450 metabolic pathway in mammalian cells. 

Key words: Mutagenicity, Polycyclic aromatic hydrocarbons, benzo[a]pyrene, Ames assay, Comet assay.