Analgesic and anti-inflammatory activities of the crude hydroalcoholic extract obtained from the bark of Hymenaea martiana

Experiments were designed to examine the analgesic and anti-inflammatory activities of the crude hydroalcoholic extract (CE) of Hymenaea martiana. The CE of H. martiana (25-200 mg/kg, i.p.) caused a graded inhibition of hindpaw oedema induced by carrageenan, PAF-acether (PAF), serotonin (5-HT), dextran and histamine (HIS). However, the CE given orally up to 500 mg/kg had no effect on the agonist-induced hindpaw oedema. The CE given intraperitoneally, but not orally, caused a graded and pronounced inhibition of His, 5-HT, bradykinin (BK) and PAF-induced increase of vascular permeability. When the CE was given orally (300 mg/kg) once a day for 15 days it caused a significant increase of agonist-induced increase of vascular permeability. The CE given either by p.o. or by i.p. routes (100-800 mg/kg) dose-dependently inhibited arachidonic acid (AA)-induced ear oedema in mice, being significantly more potent when it was given by the latter route. In contrast, CE at the same doses, failed to inhibit croton-oil-induced ear oedema in mice. The CE of H. martiana given by either i.p. or p.o. routes caused a marked and dose-dependent antinociceptive activity as revealed by its antagonistic action against acetylcholine, acetic acid or AA-induced writhing responses in mice, being more effective when given intraperitoneally. These results, and those previously reported with the CE of H. martiana in the isolated preparations, provide strong experimental support which argues in favour of the beneficial use of this plant extract in folk medicine. The exact mechanism that underlies its analgesic and anti-inflammatory profiles remains unclear, but may result from its ability to inhibit the generation of lipoxygenase and/or cyclooxygenase products of the arachidonic acid pathway.