Vitamin E prevents ethilene bis(dithiocarbamate) pesticide zineb-induced sister chromatid exchanges in Chinese hamster ovary (CHO) cells

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Summary *

The in vitro effect of the antioxidant a-tocopherol, vitamin E, on deleterious effects induced by dithiocarbamate fungicide zineb- and its commercial formulation azzurro on Chinese hamster ovary (CHO) cells was studied by using frequency of sister chromatid exchanges (SCEs), cell-cycle progression and mitotic index (MI) as genetic end points. Both zineb and azzurro activities were tested within the range of 0.1-100.0 mg/ml on exponentially growing CHO cells preincubated for 24 h in the presence or absence of 50.0. mg/ml of vitamin E. SCE frequencies increased significantly over control values in a dose-dependent manner in zineb- or azzurro-treated cultures with doses of 0.1-10.0 mg/ml and 0.1-25.0 mg/ml, respectively. When target cells were preincubated with vitamin E, the number of SCEs was significantly lower than that observed in cells exposed only to 1.0-10.0 mg/ml zineb or 1.0-25.0 mg/ml azzurro, but higher than control values. Cytotoxicity was observed at doses higher than 25.0 and 50.0 mg/ml of zineb and azzurro, respectively, regardless of the absence or presence of vitamin E. Regression analysis showed that the proliferative rate index decreased as a function of either the concentration of zineb (0.1-10.0 mg/ml dose-range) or azzurro (0.1-25.0 mg/ml dose-range) titrated into cultures. For both chemicals, progressive dose-related inhibition of the mitotic activity from cultures was observed when 10.0 mg/ml of zineb and 1.0-25.0 mg/ml of azzurro were employed. However, no significant alteration in cell-cycle progression or in MI was observed between vitamin E-preincubated cultures and those treated only with zineb and azzurro. Information provided by the agent in SIGEVA