Mass Spectrometric Characterization of an Acid-Labile Adduct Formed with 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine and Albumin in Humans

作者：Wang, Yi; Villalta, Peter W.; Peng, Lijuan; Dingley, Karen; Malfatti, Michael A.; Turteltaub, K. W.; Turesky, Robert J.^*

来源：Chemical Research in Toxicology, 2017, 30(2): 705-714.

DOI：10.1021/acs.chemrestox.6b00426

• HETEROCYCLIC AROMATIC-AMINES
• N-OXIDIZED METABOLITES
• HUMAN SERUM-ALBUMIN
• CREATING CONTEXT
• PROTEIN ADDUCTS
• COOKED MEAT
• CARCINOGEN
• PHIP
• HEMOGLOBIN
• BIOMARKERS

2-Amino-1-methyl-6-phenylimidazo [4,5-b]-pyridine (PhIP) is a carcinogenic heterocyclic aromatic amine formed during the high-temperature cooking of meats. The cytochrome P450-mediated N-hydroxylation of the exocyclic amine group of PhIP produces 2-hydroxyamino-1-methyl-6-phenylimidazo[4,5-b]pyridine, an electrophilic metabolite that forms adducts with DNA and proteins. Previous studies conducted by our laboratory showed that the reaction of N-oxidized PhIP metabolites with human albumin in vitro primarily occurs at the Cys(34) residue, to produce an acid labile linked sulfinamide adduct. On the basis of these findings, we developed a sensitive ultraperformance liquid chromatography-mass spectrometry method to measure acid-labile albumin- PhIP adducts in human volunteers administered a dietary-relevant dose of C-14-labeled PhIP [Dingley, K. H., et al. (1999) Cancer Epidemiol., Biomarkers Prey. 8, 507-512]. Mild acid treatment of albumin (0.1 N HCI, 37 degrees C for 1 h) or proteolytic digestion with Pronase [50 mM ammonium bicarbonate buffer (pH 8.5) at 37 degrees C for 18 h] released similar amounts of covalently bound PhIP, which was characterized by multistage scanning and quantified by Orbitrap mass spectrometry. The amount of [C-14]PhIP recovered by acid treatment of albumin 24 h following dosing accounted for 7.2-21.3% of the [C-14]PhIP bound to albumin based on accelerator mass spectrometry measurements. 2-Amino-1-methyl-6(5-hydroxy)phenylimidazo[4,5-b]pyridine, a hydrolysis product of the Cys(34) S-N linked sulfenamide adduct of PhIP, was not detected in either acid-treated or protease treated samples. These findings suggest that a portion of the PhIP bound to albumin in vivo probably occurs as an acid-labile sulfinamide adduct formed at the Cys(34) residue.

• 出版日期2017-2
• 单位武汉轻工大学