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

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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.