Effects of the Fusarium mycotoxins zearalenone and deoxynivalenol on the mitochondrial methylthiazol tetrazolium-cleavage activity of monolayer cells.

The application of a modified colorimetric assay for the evaluation of mycotoxin-derived cytotoxicity is reported. Using four mammalian monolayer cell types (swine kidney, African green monkey kidney, Madin Darbin canine kidney and bovine embryonic lung cells), the influence of the mycotoxins zearalenone and deoxynivalenol on the cellular methylthiazoltetrazolium (MTT)-cleavage activity was evaluated after different toxin exposure times. The yellow tetrazolium salt is converted by mitochondrial enzymes of metabolically active cells into purple formazan products. These crystals were dissolved in dimethylsulphoxide to obtain a homogeneous solution, the optical density of which was suitable for precise spectrophotometric measurement by a plate reader. Zearalenone proved to be less cytotoxic than deoxynivalenol and even enhanced the cleavage activity of the cell types tested. At concentrations of 10 and 100 mug/ml, deoxynivalenol showed a marked suppressive effect on the activity of all cell types, depending on the length of the incubation time. The results indicate that monolayers are useful targets in the MTT assay for investigating the action of mycotoxins and for performing comparative studies in mammalian cells.