Discovery of ecopladib, an indole inhibitor of cytosolic phospholipase A2α

The synthesis and structure-activity relationship of a series of indole inhibitors of cytosolic phospholipase A(2)alpha (cPLA(2)alpha, type IVA phospholipase) are described. Inhibitors of cPLA(2)alpha are predicted to be efficacious in treating asthma as well as the signs and symptoms of osteoarthritis, rheumatoid arthritis, and pain. The introduction of a benzyl sulfonamide substituent at C2 was found to impart improved potency of these inhibitors, and the SAR of these sulfonamide analogues is disclosed. Compound 123 (Ecopladib) is a sub-micromolar inhibitor of cPLA(2)alpha in the GLU micelle and rat whole blood assays. Compound 123 displayed oral efficacy in the rat carrageenan air pouch and rat carrageenan-induced paw edema models.