ABSTRACT
We report the design of novel, potent cPLA(2)α inhibitors that possess an α-methyl-2-ketothiazole that acts as a serine-reactive moiety. We describe the optimization of the series for potency and metabolic stability towards ketone reduction. This was achieved by attenuating the reactivity of the ketone using a combination of electronic and steric effects.
Subject(s)
Drug Design , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Group IV Phospholipases A2/antagonists & inhibitors , Ketones/chemistry , Thiazoles/chemical synthesis , Thiazoles/pharmacology , Animals , Drug Stability , Enzyme Activation/drug effects , Enzyme Inhibitors/chemistry , HL-60 Cells , Humans , Inhibitory Concentration 50 , Ketones/chemical synthesis , Ketones/pharmacology , Magnetic Resonance Spectroscopy , Molecular Structure , Oxidation-Reduction , Rats , Serine/chemistry , Thiazoles/chemistryABSTRACT
By careful analysis of experimental X-ray ligand crystallographic protein data across several inhibitor series we have discovered a novel, potent and selective series of iNOS inhibitors exemplified by compound 8.
Subject(s)
Enzyme Inhibitors/chemistry , Isoxazoles/chemistry , Nitric Oxide Synthase Type II/antagonists & inhibitors , Pyridines/chemistry , Animals , Binding Sites , Computer Simulation , Crystallography, X-Ray , Drug Evaluation, Preclinical , Enzyme Inhibitors/chemical synthesis , Enzyme Inhibitors/pharmacology , Humans , Isoxazoles/chemical synthesis , Isoxazoles/pharmacology , Mice , Microsomes, Liver/metabolism , Nitric Oxide Synthase Type II/metabolism , Protein Structure, Tertiary , Pyridines/pharmacology , RatsABSTRACT
Using knowledge of the substrate specificity of cPLA(2) (phospholipases A(2)), a novel series of inhibitors of this enzyme were designed based upon a three point model of inhibitor binding to the enzyme active site comprising a lipophilic anchor, an electrophilic serine "trap", and an acidic binding moiety. The resulting 1,3-diheteroatom-substituted propan-2-ones were evaluated as inhibitors of cPLA(2) in both aggregated bilayer and soluble substrate assays. Systematic variation of the lipophilic, electrophilic, and acidic groups revealed a well-defined structure-activity relationship against the enzyme. Optimization of each group led to compound 22 (AR-C70484XX), which contains a decyloxy lipophilic side chain, a 1,3-diaryloxypropan-2-one moiety as a unique serine trap, and a benzoic acid as the acidic binding group. AR-C70484XX was found to be among the most potent in vitro inhibitors of cPLA(2) described to date being more than 20-fold more active against the isolated enzyme (IC(50) = 0.03 microM) than the standard cPLA(2) inhibitor, arachidonyl trifluoromethyl ketone (AACOCF(3)), and also greater than 10-fold more active than AACOCF(3) against the cellular production of arachidonic acid by HL60 cells (IC(50) = 2.8 microM).
Subject(s)
Enzyme Inhibitors/chemical synthesis , Phospholipases A/antagonists & inhibitors , Propane/analogs & derivatives , Arachidonic Acid/analysis , Arachidonic Acid/biosynthesis , Cytosol/enzymology , Drug Design , Enzyme Inhibitors/pharmacology , HL-60 Cells/drug effects , HL-60 Cells/metabolism , Humans , Ketones/chemical synthesis , Ketones/pharmacology , Lipid Bilayers/metabolism , Structure-Activity RelationshipABSTRACT
The high lipophilicity of a series of cytosolic phospholipase A(2) inhibitors has been reduced by the modification of a decyloxyphenyl chain designed to mimic the arachidonyl group of the natural substrate. These changes have resulted in an improvement in the whole cell potency of the inhibitors.