Glutathione trapping to measure microsomal oxidation of furan to cis-2-butene-1,4-dial.
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 alpha-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.
Peterson
Lisa A
LA
The Cancer Center, University of Minnesota, Mayo Mail Code 806, 420 Delaware St. S.E., Minneapolis, MN 55455, USA. peter431@umn.edu
Cummings
Meredith E
ME
Vu
Choua C
CC
Matter
Brock A
BA
D000447:Aldehydes / Q000378:metabolism*; D000818:Animals; D001681:Biological Assay; D002851:Chromatography, High Pressure Liquid; D019392:Cytochrome P-450 CYP2E1 / Q000378:metabolism; D004563:Electrochemistry; D005663:Furans / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D010084:Oxidation-Reduction; D051381:Rats; D011916:Rats, Inbred F344
D000447:Aldehydes; D005663:Furans; C015977:malealdehyde; D019392:Cytochrome P-450 CYP2E1; D005978:Glutathione; C039281:furan