Abstract
The enzyme coenzyme A-independent transacylase (CoA-IT) has been demonstrated to be the key mediator of arachidonate remodeling, a process that moves arachidonate into 1-ether-containing phospholipids. Blockade of CoA-IT by reversible inhibitors has been shown to block the release of arachidonate in stimulated neutrophils and inhibit the production of eicosanoids and platelet-activating factor. We describe novel inhibitors of CoA-IT activity that contain a β-lactam nucleus. β-Lactams were investigated as potential mechanism-based inhibitors of CoA-IT on the basis of the expected formation of an acyl-enzyme intermediate complex. Two β-lactams, SB 212047 and SB 216754, were shown to be specific, time-dependent inhibitors of CoA-IT activity (IC50 = 6 and 20 μm, respectively, with a 10-min pretreatment time). Extensive washing and dilution could not remove the inhibition, suggesting it was irreversible. In stimulated human monocytes, SB 216754 decreased the production of eicosanoids in a time-dependent manner. In an in vivo model of phorbol ester-induced ear inflammation, SB 216754 was able to inhibit indices of both edema and cell infiltration. Taken together, the results support two hypotheses: 1) CoA-IT activity is important for the production of inflammatory lipid mediators in stimulated cells andin vivo and 2) the mechanism by which CoA-IT acts to transfer arachidonate is through an acyl-enzyme intermediate.
Footnotes
- Received June 11, 1997.
- Accepted October 31, 1997.
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Send reprint requests to: Dr. James D. Winkler, Department of Immunopharmacology, UW-2532, SmithKline Beecham Pharmaceuticals, 709 Swedeland Road, P.O. Box 1539, King of Prussia, PA 19406. E-mail:james_d_winkler{at}sbphrd.com
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This work was supported in part by National Institute of Health Grants AI24985 and AI26771.
- The American Society for Pharmacology and Experimental Therapeutics
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