title: Disposition and metabolism of the food mutagen 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) in rats.
abstract: The disposition and metabolism of a common food mutagen, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), was studied in rats. Five rats of both sexes were given a single oral dose of 14C-labeled MeIQx (3-4 mg/kg body wt). The male rats excreted 36% of the radioactivity and 15% of the mutagenic activity of the dose given in the urine collected during the first 24 h. In the females the corresponding urine contained 41% of the radioactivity and 12% of the mutagenicity. During the next 48 h only 1-3% of the radioactive dose was excreted in urine. The remaining dose was excreted in the feces except of less than 1% that was retained by the tissues after 72 h. The liver and kidney retained more radioactivity than other organs. In a separate study the metabolites of bile, urine and feces of both sexes were investigated. After a single oral dose of 20 mg 14C-labeled MeIQx/kg body wt, three major non-mutagenic metabolites were identified. These were 2-amino-4(or 5)-(beta-D-glucuronopyranosyloxy)-3,8-dimethylimidazo[4,5-f] quinoxaline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxalin-4(or 5)-yl sulfate and N-(3,8-dimethylimidazo[4,5-f]quinoxalin-2-yl) sulfamate. Another two metabolites present in bile, urine and feces were 2-(beta-D-glucuronopyranosylamino)-3,8-dimethylimidazo[4,5-f ] quinoxaline and 2-amino-8-hydroxymethyl-3-methylimidazo[4,5-f]quinoxalin-4 (or 5)yl sulfate. All metabolites were essentially non-mutagenic. Most of the mutagenicity still present in bile, urine and feces could be explained by unchanged MeIQx. Unchanged MeIQx was the most abundant form excreted in urine.
authors.affiliation: Department of Applied Nutrition, Chemical Center, Lund, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Sjödin
authors.forename: H
authors.initials: H
authors.lastname: Wallin
authors.forename: J
authors.initials: J
authors.lastname: Alexander
authors.forename: M
authors.initials: M
authors.lastname: Jägerstad
mesh_terms: D000818:Animals; D001646:Bile / Q000378:metabolism; D001711:Biotransformation; D002250:Carbon Radioisotopes; D005243:Feces / Q000032:analysis; D005260:Female; D008297:Male; D009152:Mutagenicity Tests; D009153:Mutagens / Q000493:pharmacokinetics*; D011810:Quinoxalines / Q000378:metabolism / Q000493:pharmacokinetics* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012486:Salmonella typhimurium / Q000187:drug effects; D012737:Sex Factors; D014018:Tissue Distribution
chemical_list: D002250:Carbon Radioisotopes; D009153:Mutagens; D011810:Quinoxalines; C036990:2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline