Study of the mechanism of todralazine antimutagenic activity: the effect upon mutagenicity of daunorubicine.

Todralazine markedly reduced the mutagenic activity of the standard direct-acting mutagen--daunorobicine (DRC)--in the Ames test. Spectrophotometric measurements proved that todralazine did not interact with DRC in water solution. Todralazine neither interacted with calf thymus DNS in vitro, nor changed the interaction of DRC with DNA. Therefore we concluded that the decrease of DRC mutagenicity observed in the Ames test should be explained rather in terms of a bioantimutagenic than a desmutagenic activity of todralazine.