BMS-229724 Is a Tight-Binding Inhibitor of Cytosolic Phospholipase A2 That Acts at the Lipid/Water Interface and Possesses Anti-Inflammatory Activity in Skin Inflammation Models

• Published in: The Journal of pharmacology and experimental therapeutics 2001-07, Vol.298 (1), p.376-385
• Main Authors: Burke, James R., Davern, Lynda B., Stanley, Paul L., Gregor, Kurt R., Banville, Jacques, Remillard, Roger, Russell, John W., Brassil, Patrick J., Witmer, Mark R., Johnson, Graham, Tredup, Jeffrey A., Tramposch, Kenneth M.
• Format: Article
• Language: English
• Subjects: Administration, Oral; Administration, Topical; Animals; Anti-Inflammatory Agents - pharmacology; Anti-Inflammatory Agents - therapeutic use; Carcinogens; Chlorobenzenes - pharmacology; Chlorobenzenes - therapeutic use; Dinoprostone - antagonists & inhibitors; Dinoprostone - metabolism; Dose-Response Relationship, Drug; Erythema - drug therapy; Erythema - metabolism; Female; Guinea Pigs; Humans; Inflammation - chemically induced; Inflammation - drug therapy; Inflammation - metabolism; Leukotriene B4 - antagonists & inhibitors; Leukotriene B4 - metabolism; Male; Mice; Neutrophils - drug effects; Neutrophils - metabolism; Phorbol Esters; Phospholipases A - antagonists & inhibitors; Phospholipases A - metabolism; Phospholipases A2; Phospholipids - metabolism; Platelet Activating Factor - antagonists & inhibitors; Platelet Activating Factor - metabolism; Rats; Rats, Sprague-Dawley; Skin; Sulfones - pharmacology; Sulfones - therapeutic use
• ISSN: 0022-3565; 1521-0103
• DOI: 10.1016/S0022-3565(24)29391-5

Cytosolic phospholipase A2 (cPLA2) catalyzes the selective release of arachidonic acid from the sn-2 position of phospholipids and is believed to play a key cellular role in the generation of arachidonic acid. BMS-229724 (4-[4-[2-[2-[bis(4-chlorophenyl)methoxy]ethyl-sulfonyl]ethoxy]phenyl]-1,1,1-trifluoro-2-butanone) was found to be a selective inhibitor of cPLA2(IC50 = 2.8 μM) in that it did not inhibit secreted phospholipase A2 in vitro, nor phospholipase C and phospholipase D in cells. The compound was active in inhibiting arachidonate and eicosanoid production in U937 cells, neutrophils, platelets, monocytes, and mast cells. With a synthetic covesicle substrate system, the dose-dependent inhibition could be defined by kinetic equations describing competitive inhibition at the lipid/water interface. The apparent equilibrium dissociation constant for the inhibitor bound to the enzyme at the interface (KI*app) was determined to be 1 · 10−5 mol% versus an apparent dissociation constant for the arachidonate-containing phospholipid of 0.35 mol%. The unit of concentration in the interface is mole fraction (or mol%), which is related to the surface concentration of substrate, rather than bulk concentration that has units of molarity. Thus, BMS-229724 represents a novel inhibitor of cPLA2, which partitions into the phospholipid bilayer and competes with phospholipid substrate for the active site. This potent inhibition of the enzyme translated into anti-inflammatory activity when applied topically (5%, w/v) to a phorbol ester-induced chronic inflammation model in mouse ears, inhibiting edema and neutrophil infiltration, as well as prostaglandin and leukotriene levels in the skin. In hairless guinea pigs, BMS-229724 was active orally (10 mg/kg) in a UVB-induced skin erythema model in hairless guinea pigs.