New pyrazole derivatives possessing amino/methanesulphonyl pharmacophore with good gastric safety profile: Design, synthesis, cyclooxygenase inhibition, anti-inflammatory activity and histopathological studies.

New series of pyrazole derivatives Va-c, VIa-c, VIIa-f, and VIII possessing amino/methanesulphonyl moiety as COX-2 pharmacophore were designed and synthesized. All compounds were evaluated for both in vitro COX inhibition and in vivo anti-inflammatory activities and all of them were more potent against COX-2 than COX-1 isozyme and showed good in vivo anti-inflammatory activity. Compounds Va, VIa, VIc and VIIa-c showed good COX-2 SI (246.8-353.8) in comparison with the COX-2 selective drug; celecoxib (326.7). Also, they showed good anti-inflammatory activity with edema inhibition (51-86 and 83-96%) relative to celecoxib (60.6 and 82.8%) after 3 and 5 h respectively. Additionally, these potent derivatives Va, VIa, VIc and VIIa-c were significantly less ulcerogenic (ulcer indexes = 0.7-2.0) than indomethacin (ulcer index = 21.3) and were of acceptable ulcerogenicity when compared with the non-ulcerogenic reference drug celecoxib (ulcer index = 1.3). The obtained ulcerogenic liability data revealed the gastric safety of these derivatives which was confirmed by the histopathological studies. Docking study was performed for all synthesized derivatives to explain their interaction with COX-2 receptor active site.