Anti-inflammatory and analgesic properties of water-ethanolic extract from Pothomorphe umbellata (Piperaceae) aerial parts

Anti-inflammatory and analgesic activities as well as the median lethal dose (LD50) of water-ethanolic extract (PHE) of the aerial parts of Pothomorphe umbellata were evaluated in animal models. The ED50 (oral) for the inhibition of carrageenan-induced rat paw edema assay was determined to be 550 mg/kg, while the LD50 was higher than 2.0 g/kg. At a dose of 550 mg/kg, PHE inhibited the inflammatory process by 48.7% (P < 0.05) on the third hour of the assay (edema peak) when compared to the untreated control. Indomethacin, the positive control used in this test, inhibited the edema by 58.6% at a dose of 10 mg/kg, when compared to the untreated control (P < 0.05). All three fractions - hexane, methylene chloride and ethyl acetate - obtained by partition of PHE with respective solvents also showed inhibition of the edema induced by carrageenan over a period of 4 h but the methylene chloride fraction showed the best activity. The activity shown by the methylene chloride fraction at 200 mg/kg was comparable to that exhibited by indomethacin at a dose of 10 mg/kg. The number of writhings induced by a 0.6% acetic acid solution intraperitoneal injection was decreased by 22% (P < 0.05) in the group treated orally with Pothomorphe umbellata crude extract. PHE also inhibited the granulomatous tissue formation in rats by 6.2% (P < 0.05). In the same assay, topically applied dexamethasone decreased the granuloma formation by 14.2%. The above results suggest that Pothomorphe umbellata crude extract has analgesic and anti-inflammatory properties supporting its folkloric use for the treatment of these conditions.