The binding of metabolites of aminoazo dyes to rat liver DNA in vivo.

Abstract

Summary 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.