Stable Isotope Dilution Analysis (SIDA) to Determine Metabolites of Furan and 2-Methylfuran in Human Urine Samples: A Pilot Study
Jonathan Isaak Kremer,
Dorothea Karlstetter,
Verena Kirsch,
Daniel Bohlen,
Carina Klier,
Jan Rotermund,
Hannah Thomas,
Lukas Lang,
Hanna Becker,
Tamara Bakuradze,
Simone Stegmüller,
Elke Richling
Affiliations
Jonathan Isaak Kremer
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Dorothea Karlstetter
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Verena Kirsch
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Daniel Bohlen
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Carina Klier
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Jan Rotermund
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Hannah Thomas
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Lukas Lang
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Hanna Becker
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Tamara Bakuradze
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Simone Stegmüller
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Elke Richling
Department of Chemistry, Division of Food Chemistry and Toxicology, RPTU Kaiserslautern-Landau, Erwin-Schrödinger-Str. 52, D-67663 Kaiserslautern, Germany
Furan and 2-methylfuran (2-MF) are food contaminants that are classified as potentially carcinogenic to humans. The main source of exposure for adults via food is coffee consumption. Furan and 2-MF are volatile, which complicates exposure assessment because their content measured in food prior to consumption does not afford a reliable dosimetry. Therefore, other ways of exposure assessment need to be developed, preferably by monitoring exposure biomarkers, e.g., selected metabolites excreted in urine. In this study, cis-2-buten-1,4-dial (BDA)-derived urinary furan metabolites Lys-BDA (l-2-amino-6-(2,5-dihydro-2-oxo-1H-pyrrol-1-yl)hexanoic acid), AcLys-BDA (l-2-(acetylamino)-6-(2,5-dihydro-2-oxo-1H-pyrrol-1-yl)hexanoic acid) and GSH-BDA (N-[4-carboxy-4-(3-mercapto-1H-pyrrol-1-yl)-1-oxobutyl]-l-cysteinyl-glycine cyclic sulfide), as well as acetyl acrolein (AcA, 2-oxo-pent-2-enal)-derived metabolites Lys-AcA (l-2-(acetylamino)-6-(2,5-dihydro-5-methyl-2-oxo-1H-pyrrol-1-yl)-hexanoic acid) and AcLys-AcA (l-2-amino-6-(2,5-dihydro-5-methyl-2-oxo-1H-pyrrol-1-yl)-hexanoic acid) and their stable isotopically labeled analogs, were synthesized and characterized through NMR and MS, and a stable isotope dilution analysis (SIDA) with UPLC-ESI-MS/MS was established. As a proof of concept, urinary samples of a four-day human intervention study were used. In the frame of this study, ten subjects ingested 500 mL of coffee containing 0.648 µmol furan and 1.059 µmol 2-MF. Among the furan metabolites, AcLys-BDA was the most abundant, followed by Lys-BDA and GSH-BDA. Exposure to 2-MF via the coffee brew led to the formation of Lys-AcA and AcLys-AcA. Within 24 h, 89.1% of the ingested amount of furan and 15.4% of the ingested amount of 2-MF were detected in the urine in the form of the investigated metabolites. Therefore, GSH-BDA, Lys-BDA, AcLys-BDA, Lys-AcA and AcLys-AcA may be suitable as short-term-exposure biomarkers of furan and 2-MF exposure.
