Anti-inflammatory activities of ethyl acetate extract of Polygonum jucundum and its phytochemical study

Polygonum spp. (Polygonaceae) has long been used as folk medicines in China to treat bacterial infection, blood coagulation and cancer and inflammatory diseases. In this study, we aimed to demonstrate the ethnopharmacological activity of Polygonum jucundum. Its ethyl acetate extract (PJE, 200, 500 mg/kg, intraperitoneal (p.o)) produced a dose-related anti-inflammatory effects (P<0.05 to 0.001) of xylene - induced ear oedema in mice and acetic acid - induced vascular permeability models in mice and did not present acute toxicity at the dose of 3000 mg/kg. We also found that PJE dose-dependently diminished the production of nitric oxide (NO), release of tumour necrosis factor TNF-α and IL-6 in lipopolysaccharide (LPS) - activated RAW264.7 cells. These data suggested that the ethnopharmacological action of P. jucundum may be due to its negative modulation of macrophage-mediated inflammatory responses by suppressing NO, TNF-α and IL-6 production. Two new sesquiterpenoids, 2α, 3β-dihydroxycinnamolide (1) and 2α-hydroxyl-3β-angeloylcinnamolide (2), and five known flavonoids isolated from the active extract are speculated to account for the observed anti - inflammatory properties of this species. In vivo anti - inflammatory activities of compound 2 at doses of 50 to 200 mg/kg were also evaluated using xylene - induced ear oedema and acetic acid-induced vascular permeability models in mice. Thus, this plant may be developed as a new therapeutic remedy for various inflammatory diseases such as arthritis.   Key words: Polygonum jucundum, anti-inflammatory activities, sesquiterpenolides.