Activity of citrinin metabolized by rat and human microsome fractions in clastogenicity and SCE assays on Chinese hamster V79-E cells

The mycotoxin citrinin is a potent inducer of chromosomal aberrations in the clastogenicity assay on V79-E cells when metabolized by rat and human liver microsomes. Rat and human liver microsomes, standardized on protein content, activate citrinin at equal levels. 5 × 10−4 M citrinin induces complex translocations in a high frequency as well as defects of chromosomal coiling. Higher concentrations are cytotoxic, lower ones are almost inactive. After metabolization of mycotoxin by rat-kidney microsomes or an S9 mix fraction containing rat liver and kidney microsomes, toxic effects predominate and chromosomal aberrations are diminished. Clastogenic citrinin concentrations do not induce an increase of SCE frequency. Although the mode of action of this mycotoxin on chromosomal structure remains obscure, possible explanations are discussed.