Induction of a SOS repair system in lysogenic bacteria by zearalenone and its prevention by vitamin E.

Zearalenone (Zen) is an oestrogenic mycotoxin produced by several Fusarium species in cereals. It induces modifications of haematological parameters in rats with cytotoxicity and inhibition of macromolecular synthesis (nucleic acids and protein). Zen and its metabolites have oestrogenic and anabolic activities and interact with human oestrogen receptors. Zen and its metabolites showed a positive DNA damaging effect in recombination tests with Bacillus subtilis. It induces sister chromatid exchange and chromosomal aberration in CHO cells. Zen was found to be capable of inducing DNA-adduct formation in mouse liver. The genotoxicity of Zen was questionable until the last decade when increasing data tended to show this toxin to be genotoxic in vivo. However the mechanism of its genotoxicity and mutagenicity has not been completely clarified. The present investigations were designed to show whether Zen induces an SOS-DNA repair response in lysogenic bacteria which have an integrated lambda-bacteriophage in their genome. Zen was found to be genotoxic in the bacterial systems from a concentration of 1.50 mM and it was also bactericidal (IC50 = 1.45 mM). In addition vitamin E (6.0-12.0 mM) added 1 h prior to the toxin proved to prevent both the genotoxic and bactericidal effects of Zen. This vitamin could be active both as an antioxidant and as a radical scavenger. The specificity of this prevention is probably due to the similarity of structure between vitamin E and Zen.