Resveratrol analogues as selective cyclooxygenase-2 inhibitors: synthesis and structure–activity relationship Original Research Article

Resveratrol (3,5,4′-trihydroxy-trans-stilbene) is found in grapes and various medical plants. Among cytotoxic, antifungal, antibacterial cardioprotective activity resveratrol also demonstrates non-selective cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) inhibition. In order to find more selective COX-2 inhibitors a series of methoxylated and hydroxylated resveratrol derivatives were synthesized and evaluated for their ability to inhibit both enzymes using in vitro inhibition assays for COX-1 and COX-2 by measuring PGE2 production. Hydroxylated but not methoxylated resveratrol derivatives showed a high rate of inhibition. The most potent resveratrol compounds were 3,3′,4′,5-tetra-trans-hydroxystilbene (COX-1: IC50 = 4.713, COX-2: IC50 = 0.0113 μM, selectivity index = 417.08) and 3,3′,4,4′,5,5′-hexa-hydroxy-trans-stilbene (COX-1: IC50 = 0.748, COX-2: IC50 = 0.00104 μM, selectivity index = 719.23). Their selectivity index was in part higher than celecoxib, a selective COX-2 inhibitor already established on the market (COX-1: IC50 = 19.026, COX-2: IC50 = 0.03482 μM, selectivity index = 546.41). Effect of structural parameters on COX-2 inhibition was evaluated by quantitative structure–activity relationship (QSAR) analysis and a high correlation was found with the topological surface area TPSA (r = 0.93). Docking studies on both COX-1 and COX-2 protein structures also revealed that hydroxylated but not methoxylated resveratrol analogues are able to bind to the previously identified binding sites of the enzymes. Hydroxylated resveratrol analogues therefore represent a novel class of highly selective COX-2 inhibitors and promising candidates for in vivo studies.