Carcinogenic activity of some heterocyclic analogs of p-dimethylaminoazobenzene.

Miller and Baumann (4), in a study of the rela tionship of the chemical structure of p-dimethyl aminoazobenzene (DAB) to its potency in induc ing hepatoma formation in rats, prepared a series of methylated derivatives of the parent compound. These workers found that 3'-methy!-DAB was not only more active than the parent compound but was the most active of all the azo dyes investigated up to that time (s). The carcinogenic action of DAB and its substitution products has been re cently reviewed and discussed (3, 5). In the present study, it seemed of interest to in vestigate the effect of changes in the nucleus or skeletal structure of DAB on the potency of this hepatic carcinogen. Accordingly, a series of hetero cyolic analogs of DAB, prepared by Faessinger and Brown (1), in which the pyridine or thiazole nu cleus was substituted for one of the benzene rings, was tested for carcinogenic activity. Owing to the presence of the hetero atom or atoms in these rings, position isomerism becomes an important factor. Therefore, the various position isomers of the analogs of DAB were synthesized and tested in the hope of obtaining a correlation of chemical structure and carcinogenic activity. It also seemed of interest to prepare' and compare the effect of the so-called Nor 1-oxides of the pyridineazo-p-di methylanilines.