Abstract
A group of cyclic imides (1–10) was designed for evaluation as a selective COX-2 inhibitors and investigated in vivo for their anti-inflammatory activity. Compounds 6a, 6b, 8a, 8b, 9a, 9b, 10a and 10b were proved to be potent COX-2 inhibitors with IC50 range of 0.1–4.0μM. In vitro COX-1/COX-2 inhibition structure–activity studies identified compound 8a as a highly potent (IC50=0.1μM), and an extremely selective [COX-2 (SI)>1000] comparable to celecoxib [COX-2 (SI)>384], COX-2 inhibitor that showed superior anti-inflammatory activity (ED50=72.4mg/kg) relative to diclofenac (ED50=114mg/kg). Molecular modeling was carried out through docking the designed compounds into the COX-2 binding site to predict if these compounds have analogous binding mode to the COX-2 inhibitors. The study showed that the homosulfonamide fragment of 8a inserted deep inside the 2°-pocket of the COX-2 active site, where the SO2NH2 group underwent H-bonding interaction with Gln192(2.95Å), Phe518(2.82Å) and Arg513(2.63 and 2.73Å). Docking study of the synthesized compound 8a into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.