title: S-(3-Aminobenzanthron-2-yl)cysteine in the globin of rats as a novel type of adduct and possible biomarker of exposure to 3-nitrobenzanthrone, a potent environmental carcinogen.
abstract: 3-Nitrobenzanthrone (3-NBA), a potent environmental mutagen and carcinogen, is known to be activated in vivo to 3-benzanthronylnitrenium ion which forms both NH and C2-bound adducts with DNA and also reacts with glutathione giving rise to urinary 3-aminobenzanthron-2-ylmercapturic acid. In this study, acid hydrolysate of globin from rats dosed intraperitoneally with 3-NBA was analysed by HPLC/MS to identify a novel type of cysteine adduct, 3-aminobenzanthron-2-ylcysteine (3-ABA-Cys), confirmed using a synthesised standard. The 3-ABA-Cys levels in globin peaked after single 3-NBA doses of 1 and 2 mg/kg on day 2 to attain 0.25 and 0.49 nmol/g globin, respectively, thereafter declining slowly to 70-80% of their maximum values during 15 days. After dosing rats for three consecutive days with 1 mg 3-NBA/kg a significant cumulation of 3-ABA-Cys in globin was observed. 3-ABA-Cys was also found in the plasma hydrolysate. Herein, after dosing with 1 and 2 mg 3-NBA/kg the adduct levels peaked on day 1 at 0.15 and 0.51 nmol/ml plasma, respectively, thereafter declining rapidly to undetectable levels on day 15. In addition, sulphinamide adducts were also found in the exposed rats, measured indirectly as 3-aminobenzanthrone (3-ABA) split off from globin by mild acid hydrolysis. Levels of both types of adducts in the globin samples parallelled very well with 3-ABA/3-ABA-Cys ratio being around 1:8. In conclusion, 3-ABA-Cys is the first example of arylnitrenium-cysteine adduct in globin representing a new promising class of biomarkers to assess cumulative exposures to aromatic amines, nitroaromatics and heteroaromatic amines.
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology, Prague, Technická 5, 166 28, Prague, Czech Republic. linharti@vscht.cz.
authors.forename: Igor
authors.identifier: http://orcid.org/0000-0003-2682-4326
authors.initials: I
authors.lastname: Linhart
authors.affiliation: National Institute of Public Health, Prague, Šrobárova 48, 10042, Prague, Czech Republic.
authors.forename: Iveta
authors.initials: I
authors.lastname: Hanzlíková
authors.affiliation: National Institute of Public Health, Prague, Šrobárova 48, 10042, Prague, Czech Republic.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Mráz
authors.affiliation: National Institute of Public Health, Prague, Šrobárova 48, 10042, Prague, Czech Republic.
authors.forename: Šárka
authors.initials: Š
authors.lastname: Dušková
mesh_terms: D000818:Animals; D001551:Benz(a)Anthracenes / Q000378:metabolism / Q000493:pharmacokinetics*; D002273:Carcinogens / Q000378:metabolism / Q000493:pharmacokinetics*; D002851:Chromatography, High Pressure Liquid; D003545:Cysteine / Q000737:chemistry / Q000378:metabolism; D000074062:Environmental Biomarkers; D005914:Globins / Q000737:chemistry*; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D010949:Plasma / Q000378:metabolism; D017208:Rats, Wistar
chemical_list: D001551:Benz(a)Anthracenes; D002273:Carcinogens; D000074062:Environmental Biomarkers; D005914:Globins; D003545:Cysteine; C117220:3-nitrobenzanthrone
keywords: 3-Nitrobenzanthrone; Arylnitrenium ions; Carcinogens; Globin adducts; New biomarker