The binding of isotopically labeled aminoazo dye metabolites to rat liver DNA and protein in vivo was investigated. Both benzenoid ring systems of 4-dimethylaminoazobenzene (DAB) bind to DNA. When rats were prefed a high riboflavin diet (which inhibits carcinogenesis by DAB), less binding of DAB metabolites to both DNA and protein was observed. However, the inhibition of binding to DNA resulting from a high riboflavin diet was significantly greater than the inhibition of binding to protein.

The binding of metabolites of the carcinogenic aminoazo dye 3′-methyl-4-dimethylaminoazobenzene to DNA in vivo was found to be 6 times greater than that observed with the noncarcinogenic dye 2-methyl-4-dimethylaminoazobenzene and 9 times greater than that observed with another noncarcinogenic dye, 3′-trifluoromethyl-4-dimethylaminoazobenzene.

These findings support the proposal that binding to DNA by a compound may be necessary to initiate carcinogenesis.

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©1967 American Association for Cancer Research.
1967
Cancer Research, Inc.