ABSTRACT
OBJECTIVE@#To study the anti-inflammatory action and cellular mechanism of Oplopanax elatus.@*METHODS@#A hot water extract of OE (WOE) was prepared and a major constituent, syringin, was successfully isolated. Its content in WOE was found to be 214.0 µg/g dried plant (w/w). Their anti-inflammatory activities were examined using RAW 264.7 macrophages and a mouse model of croton oil-induced ear edema.@*RESULTS@#In lipopolysaccharide (LPS)-treated RAW 264.7 cells, a mouse macrophage cell line, WOE was found to significantly and strongly inhibit cyclooxygenase-2 (COX-2)-induced prostaglandin E (PGE) production [half maximal inhibitory concentration (IC)=135.2 µg/mL] and inducible nitric oxide synthase (iNOS)-induced NO production (IC=242.9 µg/mL). In the same condition, WOE was revealed to inhibit NO production by down-regulating iNOS expression, mainly by interrupting mitogen activated protein kinases (MAPKs)/activator protein-1 (AP-1) pathway. The activation of all three major MAPKs, p38 MAPK, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase, was inhibited by WOE (50-300 µg/mL). On the other hand, WOE reduced PGE production by inhibiting COX-2 enzyme activity, but did not affect COX-2 expression levels. In addition, WOE inhibited the production of proinflammatory cytokines such as interleukin-6 and tumor necrosis factor-α. In croton oil-induced ear edema in mice, oral administration of WOE (50-300 mg/kg) dose-dependently inhibited edematic inflammation.@*CONCLUSION@#Water extract of OE exhibited multiple anti-inflammatory action mechanisms and may have potential for treating inflammatory disorders.
ABSTRACT
The stems of Oplopanax elatus (OE) have long been used to treat inflammatory disorders in herbal medicine, and in the previous investigation, OE was found to possess anti-inflammatory activity in lipopolysaccharide-treated macrophages, RAW 264.7 cell. OE reduces inducible nitric oxide (NO) synthase-induced NO production, and interferes with mitogen-activated protein kinase activation pathways. In the present study, the pharmacological action of the water extract of OE was examined to establish anti-arthritic action, using a rat model of adjuvant-induced arthritis (AIA). The water extract of OE administered orally inhibited AIA-induced arthritis at (100 – 300) mg/kg/day. The paw edema was significantly decreased, in combination with reduced production of pro-inflammatory cytokines. The action mechanism includes an inhibition of MAPKs/nuclear transcription factor-κB activation. These new findings strongly suggest that OE possesses anti-arthritic action, and may be used as a therapeutic agent in inflammation-related disorders, particularly in arthritic condition.