Abstract
In this study, we investigated the possible involvement of acyl-CoA, reactive intermediary metabolites of 2-arylpropionic acids (profens), in protein adduct formation in rat liver homogenate and in human serum albumin (HSA) in buffer. (RS)-[1-14C]-2-Phenylpropionic acid (14C-2-PPA, 1 mM) was incubated with rat liver homogenate (1.5 mg/ml) in the presence of cofactors of acyl-CoA formation (Mg2+, ATP, and CoA). Aliquots of the incubation mixture were analyzed for covalent binding and acyl-CoA formation over a 3-h period. High-performance liquid chromatographic analysis of the products from such incubations showed the presence of 2-phenylpropionyl-S-acyl-CoA (2-PPA-CoA), which was confirmed by coelution with authentic 2-PPA-CoA, as well as by mass spectrometry. In the same incubations, 2-PPA was shown to bind covalently to hepatic proteins in a time- and ATP-dependent fashion. Inhibition of 2-PPA-CoA formation by acyl-CoA synthetase inhibitors, such as palmitic acid, lauric acid, octanoic acid, and ibuprofen, markedly decreased the extent of covalent binding of 2-PPA to hepatic proteins. Results from these in vitro studies strongly suggest that acyl-CoA thioester derivatives are chemically reactive and are able to bind covalently to tissue proteins in vitro, and, therefore, may contribute significantly to covalent adduct formation of profen drugs in vivo.
Footnotes
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↵ 1 Present address: Department of Chemical Engineering, Room 237 Chemical Engineer Building, P. O. Box 116005, University of Florida, Gainesville, FL 32611-6005.
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↵ 2 Present address: Pharmacia Corporation, Global Drug Metabolism, 301 Henrietta St., Kalamazoo, MI 49007.
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↵ 3 Abbreviations used are: 2-PPA, 2-phenylpropionic acid; 2-PPA-CoA, 2-phenylpropionyl-S-acyl-CoA; DTT, dithiothreitol; HSA, human serum albumin; HPLC, high-performance liquid chromatography.
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This work was supported in part by National Institutes of Health Grant GM 36633. M.O.O.'s participation was supported by the Summer Undergraduate Program in Engineering Research at Berkeley (SUPERB).
- Received September 30, 2002.
- Accepted February 18, 2003.
- The American Society for Pharmacology and Experimental Therapeutics
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