MUTAGENICITY OF STRUCTURALLY RELATED PHENYLAZO-3-PYRIDINES IN SALMONELLA-TYPHIMURIUM

Studies were conducted to explore structure-activity relationships for 4'-N,N-dimethylamino-1'-phenylazo-3-pyridine and nine structurally re lated compounds in Salmonella typhimurium tester strains TA1535, TA100 , TA1537, TA1538, TA98. Each compound was tested for mutagenicity at f ive or more concentrations that varied from 10-5000 mug/plate. We used the standard plate test and the investigations were carried out both in the absence and presence of Aroclor-1254-induced rat-liver homogena te and the components of the NADPH-generating system. Negative respons e was observed for 4'-N,N-dimethylamino-1'-phenylazo-3-pyridine and fi ve of its analogues (4'-N,N-diethylamino-1'-phenylazo-3-pyridine; i-(b eta-hydroxyethylamino)-1'phenylazo-3-pyridine; 4'-N-methylamino sulfon ic acid-1'-phenylazo-3-pyridine; imethyl-amino-6'-acetamido-1'phenylaz o-3-pyridine, and oxyethyl-amino)-6'-methyl-1'phenylazo-3-pyridine). W hen S9 induced by Aroclor-1254 was present, the compound N,N-dimethyla mino-6-methoxy-1'phenylazo-3-pyridine exhibited mutagenic activity in the two strains TA1538 and TA98. The compound 4',6'-diamino-3-methyl-1 '-phenylazo-3-pyridine was also mutagenic, both in the presence and in the absence of S9 mix. The two compounds N,N-dimethylamino-6-butoxy-1 '-phenylazo-3-pyridine and azo-3-[6-N,N-di-(beta-hydroxyethylamino)]-p yridine were either weakly mutagenic or nonmutagenic. On the basis of these data, it is concluded that the mutagenicity of phenylazo-3-pyrid ines, like monocyclic aromatic amines and azo dyes, is influenced by t he nature of the substituent chemical groups and their positions in th e molecular structure of the compounds.