title: Reduction to benzidine is not necessary for the covalent binding of a benzidine azodye to rat liver DNA.
abstract: The DNA binding of 2 benzidine azodyes, Congo Red and Direct Blue 6, was compared in rat liver. Both dyes showed binding consequent upon metabolism to benzidine, and in each case hydrolysis of the liver DNA yielded N-(deoxyguanosin-8-yl)-N'-acetylbenzidine. The majority of Direct Blue 6-derived radioactivity bound to DNA was present as at least one other novel species. Our preliminary work on the major Direct Blue 6 DNA adduct suggests its structure may be disodium 8-amino-2-[4-(N-deoxyguanosin-8-yl)-aminobiphenyl-4'-yl] azo-1-hydroxynaphthalene-3,6-disulphonate. This adduct may form as a result of the susceptibility of the dye to hepatic azoreductase and its apparent existence may explain the observed potent carcinogenicity of dyes such as Direct Blue 6.
mesh_terms: D000818:Animals; D001391:Azo Compounds / Q000378:metabolism*; D001560:Benzidines / Q000378:metabolism; D002273:Carcinogens; D002851:Chromatography, High Pressure Liquid; D003224:Congo Red / Q000378:metabolism*; D004247:DNA / Q000378:metabolism*; D007274:Injections, Intraperitoneal; D008099:Liver / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012588:Scintillation Counting; D014316:Tritium
chemical_list: D001391:Azo Compounds; D001560:Benzidines; D002273:Carcinogens; D014316:Tritium; C017261:direct blue 6; D003224:Congo Red; D004247:DNA; C034938:N-acetylbenzidine