The role of ethyl and fluorine substitution in the 4'-position for N,N-diethyl-4-aminoazobenzene mutagenicity and azo reduction.

The mutagenicity and azo reduction rate of N,N-diethyl-4-aminoazobenzene (DEAB) were influenced by substitution in the 4'-position with a ethyl or a fluorine group. The parent dye (DEAB) was shown to be slightly mutagenic with Salmonella typhimurium TA98 using Aroclor 1254-pretreated 9000 x g supernatant fractions from rat liver. Introduction of a 4'-ethyl group in DEAB did not affect mutagenicity of the dye, but a 4-fluoro group markedly enhanced its mutagenicity. DEAB underwent azo reduction and its reduction rate was influenced by 4'-substituents. A 4'-fluoro group in DEAB increased its azo reduction rate, while a 4'-ethyl group abolished it. Inhibitors of cytochrome P-450 also inhibited 4'-fluoro-DEAB mutagenicity and azo reduction.