Effect of eugenol on the mutagenicity of benzo[a]pyrene and the formation of benzo[a]pyrene-DNA adducts in the λ-lacZ-transgenic mouse

To study the possible reduction by eugenol of the mutagenicity and genotoxicity of benzo[a]pyrene (B[a]P) in vivo, the λ-lacZ-transgenic mouse strain 40.6 (Muta^TMMouse) was used. Male mice were fed a diet containing 0.4% (w/w) eugenol or a control diet for 58 days. On day 10, half of the mice received an i.p. dose of 100 mg/kg b.w. B[a]P. The lacZ mutants were recovered by packaging of DNA isolated from liver into lambda phage, and expressed in E. coli C lacZ⁻recA⁻galE⁻ bacteria. In both control mice and mice fed the eugenol diet, B[a]P treatment resulted in a similar, significant increase in lacZ mutant frequency. Eugenol was not mutagenic by itself. By ³²P-postlabelling analysis of the liver DNA using an analysis method with chromatographic conditions for B[a]P-DNA adducts, no effect of eugenol on the formation of B[a]P-DNA adducts in the λ-lacZ-transgenic mouse was found. By ³²P-postlabelling analysis using an alkenybenzene solvent system the amount of B[a]P-DNA adducts was lower in mice fed the eugenol diet than in mice fed the control diet but the decrease was not statistically significant. However, one spot indicative of an eugenol-associated DNA adduct was detected. The present data provide no evidence for antimutagenic or antigenotoxic potential of eugenol in vivo. Furthermore, they suggest genotoxicity in vivo of eugenol per se.