Effects of an ethanolic extract and fractions from Piper glabratum (Piperaceae) leaves on pain and inflammation.

In the state of Mato Grosso do Sul, Brazil, Piper glabratum leaves are used as a popular medicine for pain and inflammation. We performed a phytochemical analysis and evaluated the effects of ethanolic extract (EEPG) obtained from leaves of P. glabratum on toxicity as well as the effects of application of the hexanic fraction (HXPG) and the hydroalcoholic fraction (HAPG) obtained from the EEPG on inflammatory parameters and pain in mice. Swiss mice were treated with EEPG (30-300 mg/kg body weight (b.w.)), HXPG (19.5 mg/kg b.w.) or HAPG (83.37 mg/kg b.w.) and then subjected to carrageenan-induced pleurisy and paw oedema tests, the spontaneous pain, and zymosan-induced intra-articular inflammation. Wistar rats were treated with EEPG to assess acute toxicity. Phytochemical analysis of the fractions demonstrated the presence of phytol and mixture of stigmasterol and β-sitosterol in the fractions. In the acute toxicity test, LD50 above 2000 mg/kg b.w. was observed. The treatments reduced oedema, cold and mechanical hyperalgesia, leukocyte migration and protein exudation. The antihyperalgesic and anti-inflammatory properties of EEPG and fractions were demonstrated in the present study. These results from EEPG and HXPG may be related, at least in part, to modulation of the inflammatory mediators by phytol, stigmasterol and β-sitosterol.