Polygonatum kingianum rhizome extract alleviates collagen antibody-induced arthritis by modulating proinflammatory cytokine production in mice

Objective: To evaluate the anti-arthritic effects of Polygonatum kingianum rhizome extract using both in vitro and in vivo models.Methods: Lipopolysaccharide-induced RAW 264.7 macrophages were treated with an ethanol extract of Polygonatum kingianum rhizomes at different concentrations to determine nitric oxide and prostaglandin E2 (PGE2) production. For in vivo study, Polygonatum kingianum ethanol extract was further investigated for its antiinflammatory effect in a mouse model with collagen antibody-induced arthritis. Phytochemical study of Polygonatum kingianum ethanol extract was also performed.Results: Saponins (142 mg/g total yield) was the main component in the Polygonatum kingianum ethanol extract. 5α,8α-ergosterol peroxide, (E,E)-9-oxooctadeca-10,12-dienoic acid and 3-(2’-hydroxy-4’-methoxy-benzyl)-5,7-dihydroxy-8-methyl-chroman-4-one were isolated from the extract. Polygonatum kingianum ethanol extract exhibited potential anti-inflammatory effects by inhibiting nitric oxide and PGE2 production in RAW 264.7 cells in a dose-dependent manner. The level of arthritis in mice with collagen antibody-induced arthritis was significantly reduced (P<0.01) after treatment with Polygonatum kingianum ethanol extract, particularly at a dose of 1 000 mg/kg body weight. Besides, the extract demonstrated the regulatory effects on serum tumor necrosis factor- alpha, interleukin-6, and interleukin-10 in treated mice.Conclusions: Polygonatum kingianum ethanol extract has beneficial effects on inflammatory cytokine regulation and PGE2 inhibition in an experimental mouse model with collagen antibody-induced arthritis. The phytochemical screening reveals that the saponin, as the main component, and sterols (daucosterol and 5α,8α-ergosterol peroxide) from Polygonatum kingianum ethanol extract may contribute to its promising in vitro and in vivo anti-inflammatory activities.