Evaluation of antimutagenic effect of todralazine in cultured lymphocytes

Todralazine, an antihypertensive drug from the hydrazinophthalazine group, significantly decreased the activities of benzoa]pyrene and mitomycin C in three short-term genotoxicity tests in human lymphocyte cultures. The thioguanine resistance test, the cytokinesis-blocked micronucleus assay and the sister chromatid exchange test were used to demonstrate the antimutagenicity of todralazine. Todralazine lowered the level of free radicals generated by human granulocytes in vitro in the presence of benzoa] pyrene and also in the presence of the granulocyte activator and tumor promoter phorbol myristate acetate. These results, together with our previous data obtained in the standard bacterial Ames test, strongly suggest that todralazine is a good antimutagen in vitro and deserves further research on its inhibitory action on mutagenesis and carcinogenesis.