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

Journal Article · · Chemical Research in Toxicology
 [1];  [2];  [3];  [4];  [4];  [4]; ORCiD logo [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States). Masonic Cancer Center and Dept. of Medicinal Chemistry
  2. Univ. of Minnesota, Minneapolis, MN (United States). Masonic Cancer Center
  3. Wuhan Polytechnic Univ., Wuhan (China). School of Food Science and Engineering
  4. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Biosciences and Biotechnology Division, Center for Accelerator Mass Spectrometry
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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 Cys34 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 14C-labeled PhIP [Dingley, K. H., et al. (1999) Cancer Epidemiol., Biomarkers Prev. 8, 507–512]. Mild acid treatment of albumin (0.1 N HCl, 37 °C for 1 h) or proteolytic digestion with Pronase [50 mM ammonium bicarbonate buffer (pH 8.5) at 37 °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 [14C]PhIP recovered by acid treatment of albumin 24 h following dosing accounted for 7.2–21.3% of the [14C]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 Cys34 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 Cys34 residue.

Research Organization:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA)
Grant/Contract Number:
AC52-07NA27344
OSTI ID:
1513115
Report Number(s):
LLNL-JRNL-769924; 961189
Journal Information:
Chemical Research in Toxicology, Vol. 30, Issue 2; ISSN 0893-228X
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 9 works
Citation information provided by
Web of Science

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Cited By (4)

Recent advances in heterocyclic aromatic amines: An update on food safety and hazardous control from food processing to dietary intake journal December 2019
Mass Spectrometry-Based Methodologies for Targeted and Untargeted Identification of Protein Covalent Adducts (Adductomics): Current Status and Challenges journal April 2019
Biomonitoring an albumin adduct of the cooked meat carcinogen 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine in humans journal September 2018
A stable isotope dilution tandem mass spectrometry method of major kavalactones and its applications journal May 2018

Figures / Tables (11)

Table 1(p. 28)table Table 1
Table 2(p. 29)table Table 2
Table 3(p. 30)table Table 3
Table 4(p. 31)table Table 4
Table 5(p. 32)table Table 5
Scheme 1(p. 34)figure Scheme 1
Figure 1(p. 36)figure Figure 1
Figure 2(p. 37)figure Figure 2
Figure 3(p. 38)figure Figure 3
Figure 4(p. 39)figure Figure 4
Figure 5(p. 40)figure Figure 5

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