Abstract
Furan is a liver carcinogen and toxicant. Furan is oxidized to the reactive dialdehyde, cis-2-butene-1,4-dial, by microsomal enzymes. This reactive metabolite readily reacts with glutathione nonenzymatically to form conjugates. A high-performance liquid chromatography-electrochemical method for the detection of cis-2-butene-1,4-dial-glutathione (GSH) conjugates in microsomal preparations was developed to measure the extent of furan metabolism to cis-2-butene-1,4-dial in vitro. Previously unobserved mono-GSH reaction products of cis-2-butene-1,4-dial were detected in addition to the already characterized bis-GSH conjugates. Chemical characterization of these compounds indicated that the α-amino group of glutathione had reacted with cis-2-butene-1,4-dial to form a thiol-substituted pyrrole adduct. The analytical method was used to estimate the extent of furan oxidation in rat liver microsomes from untreated or acetone-pretreated F344 rats as well as in human P450 2E1 Supersomes. Our results confirm that cytochrome P450 2E1 can catalyze the oxidation of furan to cis-2-butene-1,4-dial. However, the data are also consistent with the involvement of other P450 enzymes in the oxidation of furan in untreated animals. This assay will be a valuable tool to explore tissue and species differences in rates of furan oxidation.
Footnotes
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This research was funded by ES-10577 from the National Institutes of Health. An instrument grant from the Minnesota Medical Foundation was used to purchase the electrochemical detector. Portions of this research were presented at the 2004 Fall National Meeting of the American Chemical Society in Philadelphia, Pennsylvania, as well as at the 7th International Meeting for the International Society for the Study of Xenobiotics in Vancouver, British Columbia, Canada.
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Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
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doi:10.1124/dmd.105.004432.
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ABBREVIATIONS: GSH, glutathione; TCEP, tris-(2-carboxyethyl)phosphine; HPLC-EC, high-performance liquid chromatography-electrochemical detection; LC-MS, liquid chromatography-mass spectrometry.
- Received February 23, 2005.
- Accepted June 29, 2005.
- The American Society for Pharmacology and Experimental Therapeutics
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