Reduction of genotoxic effects of MNNG by butylated hydroxyanisole

Butylated hydroxyanisole (BHA) is a food preservative with markedly contrad ictory effects. On one side many studies showed its antimutagenic and antic arcinogenic effects but on the other side dietary levels of BHA were report ed to cause gastrointestinal hyperplasia in rodents. We studied the influen ce of BHA on cytotoxicity, mutagenicity, and DNA-damaging activity of N-met hyl-N'-nitro-N-nitrosoguanidine (MNNG) in Chinese hamster V79 cells culture d ill vitro. Our results showed that BHA significantly reduced the frequenc y of 6-thioguanine resistant (6-TG(r)) mutations and micronuclei induced in V79 cells by MNNG. These antimutagenic effects of BHA were, however, accom panied by a very marked increase of MNNG toxicity and also slightly increas ed level of MNNG-induced DNA damage. For evaluation of toxicity we used three methods: (i) trypane blue exclusio n; (ii) plating efficiency; and (iii) intensity of cellular macromolecule s ynthesis. The level of DNA damage was measured by the comet assay. On the b asis of obtained results we suggest that BHA, which induces phase II detoxi fying enzymes, probably doesn't reduce the level of DNA damage induced in t ime of MNNG-treatment but it reduces the level of DNA damage created during a long-term period needed for expression of 6-TG(r) mutations and micronuc lei.