Anti-inflammatory and antinociceptive activities of extract, fractions and populnoic acid from bark wood of Austroplenckia populnea.

Austroplenckia populnea (Reiss) Lund is a Brazilian plant from "cerrado", which belongs to Celastraceae family, popularity know as "marmelinho-do campo, mangabeira-brava, mangabarana, vime and maria-mole". This plant is used in folk medicine to treat dysenteries and inflammatory disorders, such as rheumatism. Austroplenckia populnea bark hydroalcoholic crude extract, and its hexane, chloroform and ethyl acetate fractions, obtained by partition, as well as the isolated populnoic acid were investigated for their anti-inflammatory (carrageenan, dextran and histamine-induced rat paw oedema, histamine-induced increase in vascular permeability, and granulomatous tissue induction) and analgesic activities (writhing and hot plate tests). The ED(50) (oral) of the crude extract for the inhibition of carragenan-induced rat paw oedema assay was determined to be 200 mg/kg, which was also used in the assays with the extract and its fractions in all other experiments. Populnoic acid was administered in the dose of 50 mg/kg. Crude extract, hexane and chloroform fractions (200 mg/kg), and indomethacin (10 mg/kg) inhibited significantly (p<0.05) the formation of the carrageenan-induced rat paw oedema, measured in third hour of experiment (peak of oedema formation) by 43.2%, 37.3%, 31.1% and 59.3%, respectively. There was a significant reduction (p<0.05) in dextran-induced rat paw oedema in all groups, while in the assay using histamine as the oedematogenic agent, only the groups treated with populnoic acid (50 mg/kg) and cyproheptadine (10 mg/kg) displayed significant reduction (p<0.05). The populnoic acid and cyproheptadine reduced the peak of oedema formation (1st hour) by 41.3% and 34.7%, respectively. Only for the groups treated with populnoic acid (50 mg/kg) and cyproheptadine (10 mg/kg) it was observed a significant (p<0.05) reduction in histamine-induced increase in vascular permeability (44.8% and 80.3%, respectively). Granulomatous tissue formation was significantly inhibited (p<0.05) by both hexane fraction (46.0%) and dexamethasone (66.2%). In the analgesic assays, the crude extract and its hexane and chloroform fractions, as well as indomethacin diminished significantly the number of writhings (p<0.05) by 69.6%, 47.2%, 44.8% and 62.8%, respectively. On the other hand, none assayed sample displayed significant result in the hot plate test. Based on the obtained results it is suggested that extracts of Austroplenckia populnea bark and populnoic acid display anti-inflammatory activity, supporting its folkloric use to treat inflammatory disorders.