Synthesis, anti-inflammatory activity and COX-1/COX-2 inhibition of novel substituted cyclic imides. Part 1: Molecular docking study

A group of cyclic imides (1–13) was designed for evaluation as selective COX-2 inhibitors and investigated in vivo for their anti-inflammatory activities using carrageenan-induced rat paw edema model. Compounds 5b, 6b, 11b, 11c, 12b and 12c were proved to be potent COX-2 inhibitors with IC50 range of 0.1–1.0 μM. In vitro COX-1/COX-2 inhibition structure–activity studies identified compound 5b as a highly potent (IC50 = 0.1 μM), and an extremely selective [COX-2 (SI) = 400] comparable to celecoxib [COX-2 (SI) > 333.3], COX-2 inhibitor that showed superior anti-inflammatory activity (ED50 = 104 mg/kg) relative to diclofenac (ED50 = 114 mg/kg). A Virtual screening 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. Molecular modeling (docking) study showed that the CH3O substituents of 5b inserted deep inside the 2°-pocket of the COX-2 active site, where the O-atoms of such group underwent a H-bonding interaction with His90 (2.43, 2.83 Å), Arg513 (2.89 Å) and Tyr355 (3.34 Å). Docking study of the synthesized compound 5b into the active site of COX-2 revealed a similar binding mode to SC-558, a selective COX-2 inhibitor.

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► Cyclic imide derivatives were synthesized and screened for COX-1/COX-2 inhibition.
► Compounds with COX-2 inhibition were subjected to anti-inflammatory studies.
► Compound 5b exhibit optimal COX-2 inhibitory potency (IC50 = 0.1mM).
► This compound presents the pharmacophoric requisites for COX-2 inhibition.
► Molecular docking studies further supported the strong inhibitory activity of 5b.