Anti-inflammatory activities of gentiopicroside against iNOS and COX-2 targets

Objective: To isolate high-purity gentiopicroside from the Chinese herbal Gentiana officinalis and investigate its anti-inflammatory activity against iNOS and COX-2 targets.Methods: The purity and structures of gentiopicroside were determined by HPLC, IR, NMR, and MS. The anti-inflammatory effects of gentiopicroside were investigated by in vivo, in vitro, and molecular experiments.Results: In vitro experiment results showed that gentiopicroside inhibited nitric oxide(NO), prostaglandin E2(PGE2), and interleukin-6(IL-6) production in mouse macrophages RAW 264.7 stimulated by lipopolysaccharide. In vivo experiment found that xylene-induced mouse ear swelling was inhibited by gentiopicroside with an inhibition rate of 34.17%. Molecular docking of cyclooxygenase-2(COX-2) and inducible nitric oxide synthase(i NOS) with gentiopicroside showed that hydrogen bonds(H-bonds) were formed between the sugar fragments in gentiopicroside structure with Tyr355, Ser353, Leu352, Ser530,Arg120, and His90 of COX-2, and Glu377, Asp382, Tyr373, Tyr347, Gln263, Asn370, and Gly371 of i NOS.Thus, gentiopicroside had a lower docking score and displayed satisfactory anti-inflammatory activities.Conclusion: These results suggested that the mechanism of anti-inflammatory activity of gentiopicroside was associated with the downregulation of inflammatory cytokines, such as NO, PGE2, and IL-6, and the suppression of iNOS and COX-2. Therefore, gentiopicroside is a potential and selective iNOS and COX-2 inhibitor.