Carcinogenic Activity of Some Heterocyclic Analogs of p-Dimethylaminoazobenzene: II. Effects of Methyl Groups in the Pyridine Ring

Summary 1.A new series of compounds in which the pyridine and pyridine-1-oxide rings were substituted for a benzene ring of p -dimethylaminoazobenzene (DAB) were prepared and tested for ability to induce rat tumors. 2.The compounds tested were 4-methylpyridine-2-azo- p -dimethylaniline (4-Me-P2), 6-methylpyridine-2-azo- p -dimethylaniline (6-Me-P2), 4-methylpyridine-1-oxide-2-azo- p -dimethylaniline (4-Me-PO2), 6-methylpyridine-1-oxide-2-azo- p -dimethylaniline (6-Me-PO2), 2-methylpyridine-4-azo- p -dimethylaniline (2-Me-P4), pyridine-1-oxide-3-azo- p -dimethylaniline (PO3), 2-methylpyridine-1-oxide-4-azo- p -dimethylaniline (2-Me-PO4), 3-methylpyridine-1-oxide-4-azo- p -dimethylaniline (3-Me-PO4), and 2,6-dimethylpyridine-1-oxide-4-azo- p -dimethylaniline (2,6-diMe-PO4). 3.Over a period of 10 months9 administration of the test compounds, 4-Me-P2, 6-Me-P2, 4-Me-PO2, and 6-Me-PO2 were ineffective in tumor production. 2-Me-P4 was observed to be more effective than P4 and about equivalent to DAB. PO3 was observed to be less active than PO4 and about as active as DAB. 3-Me-PO4 seemed to be more active than DAB and about equal to m ′-Me-DAB. 2-Me-PO4 and 2,6-diMe-PO4 both appeared far more active than m ′-Me-DAB and both are more active than PO4, which was the most potent of the compounds previously tested.