Synthesis and Biological Evaluation of New imidazo[1,2-a]pyridine Derivatives as Selective COX-2 Inhibitors

The close structural similarity between cyclooxygenase (COX) isoforms and also the lack of potent selective COX-2 inhibitors with low side effects, stimulate the development of new highly selective COX-2 inhibitors. In this study, a group of imidazo[1,2-a] pyridines was designed, synthesized and investigated to identify potent and selective COX-2 inhibitors. In vitro COX inhibition assay showed that all derivatives were selective COX-2 inhibitors with IC50 values in the highly potent 0.07-0.18 mu M range and COX-2 selectivity indexes (SI) in 57-217 range. 2-(4-( methylsulfonyl) phenyl)-3-(morpholinomethyl) H-imidazo[1,2-a] pyridine (6f) which possessing p-methylsulfonyl phenyl at C-2 of imidazo[1,2-a] pyridine ring, exhibited the highest COX-2 inhibitory selectivity and potency. Molecular modeling and docking studies indicated that synthesized compounds have a binding similar to that of the known inhibitor SC-558 and also methylsulfonyl group can be inserted into the secondary pocket of COX-2. The ability of synthesized compounds for inhibition of platelet aggregation was also determined. Our results demonstrated that 6f was the most potent platelet aggregation inhibitor as well.