Anti-inflammatory, Radical-Scavenging, and Chelating Activities of Nor-Triterpenes from Galphimia Species

Anti-inflammatory and radical-scavenging activities of the methanolic extract from the leaves of Galphimia spp. collected in Morelos, Mexico, and isolated galphimidin and galphimidin B, were evaluated. Nor-triterpenes galphimidin and galphimidin B displayed anti-inflammatory activity inhibiting the nitric oxide production by the lipopolysaccharide-induced RAW 264.7 cell model, with IC50 values of 22.62 and 20.19 mu g/ml, respectively, which were higher than the crude extract with an IC50 of 42.92 mu g/ml. Furthermore, the 12-O-tetradecanoylphorbol-13-acetate-induced ear edema in mice assay displayed results of EC50 of 2.03 mg/ear to the methanolic extract, 1.91 mg/ear to galphimidin, and 1.42 mg/ear to galphimidin B. Docking analysis of galphimidin and galphimidin B at the iNOS active site indicated the negative influence of water molecules by mediating the ligand-protein interaction through hydrogen bond interactions that increase the energy expenditure. These results explain the observed anti-inflammatory action of galphimidin and galphimidin B by iNOS inhibition, which is better modulated in silico by the absence of water in the active site. The methanolic extract showed a low radical-scavenging activity inhibiting free radicals DPPH center dot with values of 57.33% compared to isoquercetin and rutin, as positive controls. Nevertheless, the crude extract displayed high activity inhibiting ABTS(center dot+) free radicals at 83.31% that was in accordance with high reducing potential of total polyphenols by the FolinCiocalteu method with value of 3591.11 mg of gallic acid/g of biomass. Galphimidin and galphimidin B did not present radical-scavenging activities but showed metal-chelating activity of 27.62 and 30.54%, which were higher values than ethylenediaminetetraacetic acid, as positive control.