The progress of small molecules against cannabinoid 2 receptor (CB2R).

[Display omitted] The two subtypes of cannabinoid receptors (CBR), namely CB 1 R and CB 2 R, belong to the G protein-coupled receptor (GPCR) superfamily and are confirmed as potential therapeutic targets for a variety of diseases such as inflammation, neuropathic pain, and immune-related disorders. Since CB 1 R is mainly distributed in the central nervous system (CNS), it could produce severe psychiatric adverse reactions and addiction. In contrast, CB 2 R are predominantly distributed in the peripheral immune system with minimal CNS-related side effects. Therefore, more attention has been devoted to the discovery of CB 2 R ligands. In view of the favorable profile of CB 2 R, many high-binding affinity and selectivity CB 2 R ligands have been developed recently. This paper reviews recent research progress on CB 2 R ligands, including endogenous CB 2 R ligands, natural compounds, and novel small molecules, in order to provide a reference for subsequent CB 2 R ligand development. [ABSTRACT FROM AUTHOR]