Synthesis of carbamide derivatives bearing tetrahydroisoquinoline moieties and biological evaluation as analgesia drugs in mice.

Transient receptor potential vanilloid 1 (TRPV1) is a ligand-gated non-selective cation channel that is considered to be an important pain integrator. Tetrahydroisoquinoline, the prototypical antagonist of TRPV1, has a clear therapeutic potential. Here, a series of carbamide derivatives of tetrahydroisoquinoline were designed and synthesized. Preliminary biological tests suggested that the compounds I 1, I 2, and I 9 had favorable TRPV1 antagonism activity. In further studies, I 1 exhibited better antinociceptive activity than the positive control BCTC in diverse pain models. All of these results suggested that I 1 can be considered as the lead candidate for the further development of antinociceptive drugs.