Antioxidant and Anti-Inflammatory Activity of Achyranthes japonica through Down-Regulation of MAPK Signaling in LPS-Activated RAW 264.7 Macrophages
Background : Achyranthes japonica Nakai (AJ) is a perennial herb with a wide distribution in East Asia including Korea, China, and Japan, and it is mainly used as a medicinal plant. In Korea, AJ has been widely used to control pain and improve symptoms in OA patients. AJ contains several important phytochemicals such as saponins, inokosterone, ecdysterone, and oleanolic acid bisdesmoside. Methods and Results : The aim of this work was to investigate the antioxidant and anti-inflammatory activities of fermented and ethanol extracts of Achyranthes japonica Nakai (AJ). The extracts showed strong reductive power and nitrite scavenging, hydroxyl radical scavenging, superoxide radical scavenging, and DNA damage prevention activities. Treatment of RAW 264.7 macrophages with AJ inhibited lipopolysaccharide (LPS)-induced NO secretion and iNOS expression without affecting cell viability. AJ also inhibited cyclooxygenase 2 (COX-2) expression, leading to the suppression of COX-2-derived prostaglandin E2 production. These inhibitory effects of AJ were accompanied by reduced production of tumor necrosis factor-α and interleukins (IL)-1β, -6, and -10. Furthermore, AJ suppressed LPS-induced phosphorylation of extracellular signal regulated kinase, c-Jun N-terminal kinase, and p38. Moreover, AJ inhibited malondialdehyde production and myeloperoxidase activity in LPS-stimulated RAW 264.7 cells. Conclusion : The antioxidant activity of plants is closely related to their medicinal properties and is widely used as a parameter to determine the bioavailability of medicinal plants. The antioxidant and biological activities of AJ extracts might be due to the synergistic actions of multiple bioactive compounds. It can be concluded that AJ extracts are a potential source of biologically important drug candidates.