Synthesis and biological evaluation of new nicotinic acid derivatives as potential anti-inflammatory agents with enhanced gastric safety profile

Abstract

Two innovative series derived from nicotinic acid scaffold were synthesized and evaluated for their anti-inflammatory activity. Ibuprofen, celecoxib and indomethacin were used as standard drugs. All the newly synthesized compounds were in vitro screened for their anti-inflammatory activity adopting 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyltetrazolium bromide dye (MTT), as well as Griess assays. The results showed that all compounds exhibited significant anti-inflammatory activity without affecting the viability of the macrophages compared to ibuprofen. In addition, compounds 4d, 4f, 4g, 4h and 5b exhibited the most potent nitrite inhibition activity and consequently superior anti-inflammatory activity with MTT results ranging between values 86.109 ± 0.51 to 119.084 ± 0.09. The most active compounds were subjected to evaluation of TNF-α, IL-6, iNOS and COX-2 levels in LPS/INF γ-stimulated RAW 264.7 macrophage cells in comparison to ibuprofen as a reference compound. The five compounds showed comparable inhibition potency of these inflammatory cytokines compared to ibuprofen. Same compounds were further in vivo evaluated for their anti-inflammatory activity via carrageenan induced arthritis in rats. Regarding the ulcerogenic profile, compound 4h showed mild infiltration of gastric mucosa superb to compound 5b displayed severe gastritis. Molecular docking of 4h and 5b in the COX-2 active site was performed to evaluate their preferential COX-2 inhibitory potency. The docking results were in accordance with the biological findings.