The micronucleus assay in mammalian cells in vitro to assess health benefits of various phytochemicals

We evaluated the protective effects of Gentiana lutea extracts (GLEx) and 6-Gingerol (6-G) on clastogenicity of N-methyl-N′-nitro-N-nitrosoguanidine (MNNG) and 7,12-dimethylbenz(α) anthracene (DMBA) in vitro on HepG2 cells using the frequencies of induced micronuclei (MN) as the end point. Pre-, post- and simultaneous treatments with GLEx or 6-G and the carcinogens were carried out. Both GLEx post- and simultaneous treatments reduced the frequencies of MN induced by MNNG and DMBA. Probably this effect is due to an increase of cytostasis and a physico-chemical interaction between GLEx and DMBA under simultaneous treatment. Pre- and simultaneous treatments with 6-G significantly reduced the yield of MNNG-induced micronuclei without affecting % of cytostasis. Simultaneous treatment with 6-G plus DMBA resulted in reduction in the frequency of MN and an increase in cytotoxicity compared to sample treated alone with DMBA, whereas a post-treatment, caused a significant decrease in the yield of MN compared with DMBA alone without any cytotoxic effect. These results are compared with our earlier data obtained in the same system with other phytochemicals. It is concluded that for a critical evaluation of the protective effects of phytochemicals, both the influence on the induced MN and induced cytostasis have to be considered.