Latest progress in the identification of novel synthetic ligands for the cannabinoid CB2 receptor

Cannabinoid receptors, belonging to the superfamily of G-protein coupled receptors, play a major role in pathophysiology of a wide range of disparate diseases. Cannabinoid CB2 receptor, which mainly locates in peripheral tissues, represents as a promising drug target for the treatment of pain, osteoporosis, liver disorders, and so on without serious CNS side effects. In the past decades, the identification and optimization of selective ligands for the CB2 receptor has been a major objective in drug discovery. In the present review, we describe recent advances in the development of novel chemotypes of the CB2 receptor selective ligands, and give a simple discussion for the corresponding structure-activity relationships of them.