Studies on Carcinogenic Azo Dyes. III. Retention of Tritium during Enzymatic Hydroxylation of 3'-Methyl-4-dimethylaminoazobenzene (4'-³H, or 5'-³H) or Chemical Substitutions of the Related Compound, and the Effect of the Repeated Administration of This Azo Dye on the Retention of Tritium

Abstract

This paper is intended to report the retention of tritium during enzymatic hydroxylation at the 4'position of 3'-methyl-4-dimethylaminoazobenzene [4'-³H, or 5'-³H] (3'-Me-DAB) or during nonenzymatic substitutions at the 4 position of 3-methylacetanilide (4-³H, or 5-³H), and the effect of the repeated administration of carcinogenic 3'-Me-DAB upon the aryl hydroxylation activity against 3'-Me-DAB (5'-³H) and retention of tritium in the hydroxylated product. The enzymically formed 3'-methyl-4'-hydroxy-4-dimethylaminoazobenzene from 3'-Me-DAB (4'-³H) retained tritium 94% on an average. Accordingly, it may be proved that the NIH shift also occurs in the enzymatic hydroxylation of 3'-Me-DAB (4'-³H). The chemically produced 4-hydroxy-, 4, 6-dibromo-, and 4-nitro-3-methylacetanilide from 3-methylacetanilide (4-³H) retained tritium approximately 65% in each case. Since no significant effect of feeding 0.06% 3'-Me-DAB for 1-4 weeks on the aryl hydroxylation activity against 3'-Me-DAB (5'-³H) and retention of tritium in the hydroxylated product from 3'-Me-DAB (4'-³H) was observed, it may be suggested that the aryl hydroxylase activity of rat liver against 3'-Me-DAB dose not be qualitatively changed during the early stage of the carcinogenesis by 3'-Me-DAB.