Structure-activity relationships of thiazole and benzothiazole derivatives as selective cannabinoid CB2 agonists with in vivo anti-inflammatory properties.

The strong therapeutic potential of CB2 receptor agonists for use as anti-inflammatory agents that lack psychiatric side effects has attracted substantial interest. We herein describe the rational design and synthesis of novel thiazole and benzothiazole derivatives and the evaluation of their binding affinity and functional activity on CB1 and CB2 receptors. The series with the general formula N-(3-pentylbenzo [d]thiazol-2(3H)-ylidene) carboxamide (compounds 6a-6d) exhibited the highest affinity and selectivity towards CB2 receptors with K_is in the picomolar or low nanomolar range, and selectivity indices (K_i hCB1/K_i hCB2) reaching up to 429 fold. Notably, these compounds also demonstrated an agonistic functional activity in cellular assays with EC₅₀s in the low nanomolar range. More interestingly, compound 6d, the 3-(trifluoromethyl)benzamide derivative, exhibited remarkable protection against DSS-induced acute colitis in mice model.