title: Hydrolytic Cleavage Products of Globin Adducts in Urine as Possible Biomarkers of Cumulative Dose: Proof of Concept Using Styrene Oxide as a Model Adduct-Forming Compound.
abstract: A new experimental model was designed to study the fate of globin adducts with styrene 7,8-oxide (SO), a metabolic intermediate of styrene and a model electrophilic compound. Rat erythrocytes were incubated with SO at 7 or 22 °C. Levels of specific amino acid adducts in globin were determined by LC/MS analysis of the globin hydrolysate, and erythrocytes with known adduct content were administered intravenously to recipient rats. The course of adduct elimination from the rat blood was measured over the following 50 days. In the erythrocytes incubated at 22 °C, a rapid decline in the adduct levels on the first day post-transfusion followed by a slow phase of elimination was observed. In contrast, the adduct elimination in erythrocytes incubated at 7 °C was nearly linear, copying elimination of intact erythrocytes. In the urine of recipient rats, regioisomeric SO adducts at cysteine, valine, lysine, and histidine in the form of amino acid adducts and/or their acetylated metabolites as well as SO-dipeptide adducts were identified by LC/MS supported by synthesized reference standards. S-(2-Hydroxy-1-phenylethyl)cysteine and S-(2-hydroxy-2-phenylethyl)cysteine, the most abundant globin adducts, were excreted predominantly in the form of the corresponding urinary mercapturic acids (HPEMAs). Massive elimination of HPEMAs via urine occurred within the first day from the erythrocytes incubated at both 7 and 22 °C. However, erythrocytes incubated at 7 °C also showed a slow second phase of elimination such that HPEMAs were detected in urine up to 50 days post-transfusion. These results indicate for the first time that globin adducts can be cleaved in vivo to modified amino acids and dipeptides. The cleavage products and/or their predictable metabolites are excreted in urine over the whole life span of erythrocytes. Some of the urinary adducts may represent a new type of noninvasive biomarker for exposure to adduct-forming chemicals.
authors.affiliation: National Institute of Public Health , Prague, Šrobárova 48, CZ-10042 Prague, Czech Republic.
authors.forename: Jaroslav
authors.initials: J
authors.lastname: Mráz
authors.affiliation: National Institute of Public Health , Prague, Šrobárova 48, CZ-10042 Prague, Czech Republic.
authors.forename: Iveta
authors.initials: I
authors.lastname: Hanzlíková
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology , Prague, Technická 5, CZ-166 28 Prague, Czech Republic.
authors.forename: Alena
authors.initials: A
authors.lastname: Moulisová
authors.affiliation: National Institute of Public Health , Prague, Šrobárova 48, CZ-10042 Prague, Czech Republic.
authors.forename: Šárka
authors.initials: Š
authors.lastname: Dušková
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology , Prague, Technická 5, CZ-166 28 Prague, Czech Republic.
authors.forename: Kamil
authors.initials: K
authors.lastname: Hejl
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology , Prague, Technická 5, CZ-166 28 Prague, Czech Republic.
authors.forename: Aneta
authors.initials: A
authors.lastname: Bednářová
authors.affiliation: National Institute of Public Health , Prague, Šrobárova 48, CZ-10042 Prague, Czech Republic.
authors.forename: Ludmila
authors.initials: L
authors.lastname: Dabrowská
authors.affiliation: Department of Organic Chemistry, Faculty of Chemical Technology, University of Chemistry and Technology , Prague, Technická 5, CZ-166 28 Prague, Czech Republic.
authors.forename: Igor
authors.initials: I
authors.lastname: Linhart
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism / Q000652:urine; D002851:Chromatography, High Pressure Liquid; D004852:Epoxy Compounds / Q000378:metabolism* / Q000652:urine*; D004912:Erythrocytes / Q000187:drug effects / Q000378:metabolism; D005914:Globins / Q000378:metabolism* / Q000652:urine*; D006868:Hydrolysis; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D053719:Tandem Mass Spectrometry; D015262:Xenobiotics / Q000378:metabolism / Q000652:urine
chemical_list: D015415:Biomarkers; D004852:Epoxy Compounds; D015262:Xenobiotics; D005914:Globins; C013690:styrene oxide