Anti-inflammatory and analgesic effects of ethanol and aqueous extracts of Pterocephalus hookeri (C.B. Clarke) Höeck.

J Ethnopharmacol. 2009 Mar 25; Zhang L, Hu JJ, Lin JW, Fang WS, Du GHAIM OF THE STUDY: This study evaluates the anti-inflammatory and analgesic activities of the ethanol and aqueous extracts of a Tibetan herb Pterocephalus hookeri (C.B. Clarke) Höeck to provide experimental evidence for its traditional use such as cold, flu and rheumatoid arthritis. MATERIALS AND METHODS: Investigations on the analgesic effects of P. hookeri (C.B. Clarke) Höeck were carried out, including hot-plate test and acetic acid-induced writhing. The anti-inflammatory activities were observed by utilizing the following models: carrageenin-induced edema of the hind paw of rats, cotton pellet-induced granuloma formation in rats, acetic acid-induced permeability, and xylene-induced ear edema in mice. The effects of the administration of indomethacin were also studied. RESULTS: It has been shown that the ethanol and aqueous extracts significantly increased the hot-plate pain threshold and reduced acetic acid-induced writhing response in mice. The ethanol and aqueous extracts remarkably inhibited the increase in vascular permeability induced by acetic acid and ear edema induced by xylene. The ethanol extract also significantly decreased the carrageenin-induced rat paw edema perimeter and inhibited the increase of granuloma weight. CONCLUSION: The results show that the ethanol and aqueous extracts have both central and peripheral analgesic activities and as anti-inflammatory effects, supporting the traditional application of this herb in treating various diseases associated with inflammation and pain.