ML193 is a potent and selective piperadinyloxadiazolone antagonist for G protein-coupled receptor (GPCR) GPR55, a receptor for L-α-lysophosphatidylinositol (LPI) which also binds synthetic cannabinoids, and signals through several endogenous pathways. GPR55 is highly abundant in the CNS as well as in intestine, bone marrow, spleen, platelets, immune and endothelial cells. Its role is not completely understood, but has been implicated in inflammatory pain, neuropathic pain, metabolic disorder, bone development, and cancer. Selective antagonists are needed to further elucidate the role of GPR55 in physiology and pathobiology. ML193 (CID1261822) has 221 nM potency for GPR55 and >145-fold, >27-fold and >145-fold antagonist selectivity against GPR35, cannabinoid receptors CB1 and CB2, respectively and >145-fold agonist selectivity against GPR35, CB1 and CB2. ML193 is inhibits the downstream responses of ERK phosphorylation with an IC50 of 65 nM and PKC βII translocation with an IC50 of 10 μM.
