Results of genotoxicity testing of theophylline on bacteria and two lines of mammalian cells.

In study of the genotoxic effects of theophylline, this substance was subjected to a series of tests. Its potential mutagenicity was followed at the level of both bacteria and mammalian cells. The capacity of the substance to damage human DNA was determined by the so-called DNA inhibition test and by the method of alkaline elution of DNA. In the absence of the enzymatic microsomal S9 fraction, theophylline showed very weak mutagenic effects on bacteria and mammalian cells. However, in both cases this weak mutagenic effect was eliminated through a simultaneous application of theophylline and the S9 fraction. The results of the remaining tests proved negative regardless of whether the S9 fraction was present or absent. Our results lead us to infer that theophylline exerts no genotoxic action under in vivo conditions.