Evaluation of antinociceptive activity of ethanol extract of bark of Polyalthia longifolia.

Ethnopharmacological relevance Polyalthia longifolia var. pendula is a very popular herb in Bangladesh due to its traditional uses in treatment of rheumatism, bone fracture and gastric ulcer. The present study was conducted to investigate the antinociceptive activity of ethanol extract of P. longifolia (EEPL) bark. Materials and methods Hot plate and tail immersion tests, acetic acid-induced writhing test, glutamate and formalin-induced paw licking tests in mice were employed in this study. In all the experiments EEPL was administered orally at the doses of 50, 100 and 200 mg/kg body weight. To investigate the possible participation of opioid system in EEPL-mediated effects, naloxone was used to antagonize the action. Results EEPL showed a significant antinociceptive activity against both heat and chemical-induced nociception. The effects were dose-dependent and significant at the doses of 100 and 200 mg/kg of EEPL. Besides, pretreatment with naloxone caused significant inhibition of the antinociceptive activity induced by EEPL, revealing the possible involvement of the opioid receptors. Conclusion These results indicate the antinociceptive activity of the bark of P. longifolia and support the ethnomedical use of this plant in treatment of different painful conditions. [ABSTRACT FROM AUTHOR]