Abstract: To screen the anti-inflammatory and analgesic active fractions from the root bark of Lespedeza davidii,and to study the mechanism of the anti-inflammatory and analgesic.The acute inflammatory models,such as xylene-induced ear swelling,egg white-induced paw swelling,and the chronic inflammatory model granuloma induced by cotton pellet implantation,were used in researching the anti-inflammatory effects of the active fractions from the root bark of Lespedeza davidii.Meanwhile,the analgesic effects of the active fractions from the root bark of Lespedeza davidii were observed by hot plate and acetic acid writhing model.To explore the anti-inflammatory and analgesic mechanism,the content of the serum TNF-α,IL-1β and foot plantar inflammatory tissue PGE₂  in rat with inflammation caused by egg white were detected,and the serum NO,MDA and PGE₂ levels in mice with pain induced by acetic acid were detected.The results showed:High- and low-dose petroleum ether fraction could significantly inhibit ear swelling in mice and paw swelling in rats.Also,petroleum ether fraction decreased the granuloma of rats.Moreover,after the treatment with high- and low-dose petroleum ether fraction,the pain threshold with hot plate method was significantly prolonged.The writhing number was reduced after administration.The petroleum ether fraction decreased significantly the content of the serum TNF-α,IL-1β and foot plantar inflammatory tissue PGE₂ in rat with inflammation caused by egg white,and decreased significantly the serum NO,MDA and PGE₂ levels in mice with pain induced by acetic acid.These results indicated that the petroleum ether fraction of the root bark of Lespedeza davidii is anti-inflammatory and analgesicactive fractions,and its mechanism of anti-inflammatory effect may be related to the reduction of TNF-α,IL-1β and PGE₂ production,and its mechanism of analgesic effect may be related to the reduction of NO,MDA and PGE₂ levels.

Key words: the root bark of Lespedeza davidii, anti-inflammatory, analgesic, active fractions, mechanism