Isolation and characterization of anti-inflammatory and analgesic compounds from Uapaca staudtii Pax (Phyllanthaceae) stem bark.

ETHNOPHARMACOLOGICAL RELEVANCE: Uapaca species including Uapacastaudtii Pax (Phyllanthaceae) are used in West Africa ethnomedicine to treat diverse ailments including pile, rheumatism, oedema and wound healing. However, the anti-inflammatory and analgesic potential as well as constituents of the Uapacastaudtii stem bark has not been investigated. AIM OF THE STUDY: The study was designed to evaluate the anti-inflammatory, analgesic, and antioxidant activities of extract and fractions ofU. staudtii stem bark, and to isolate the bioactive constituents. MATERIALS AND METHODS: The anti-inflammatory, analgesic and antioxidant activities of the ethanol extract, dichloromethane, ethyl acetate, butanol, and aqueous fractions of U. staudtii stem bark, as well as protocatechuic acid and betulinic acid isolated from the bioactive ethyl acetate fraction were evaluated in different mice models of inflammation and pain; furthermore, antioxidant assays were carried out. Chemical structures of isolated compounds were established based on spectroscopic studies and comparison with literature data. RESULTS: The ethanol extract and ethyl acetate fraction exhibited good anti-inflammatory, analgesic, and antioxidant capacity in all studied models, comparable with those of the standard drugs used. Protocatechuic acid also gave significant (p < 0.05) anti-inflammatory (83%and 88% inhibition for egg-albumin induced and xylene induced oedema, respectively), analgesic (56% inhibition and 22 s of pain suppression for acetic acid-induced and hot plate-induced pain, respectively), and antioxidant effects (97% inhibition and absorbance of 2.516 at 100 µg/mL for DPPH and FRAP assay, respectively) in all the models, whereas betulinic acid only exhibited significant (p < 0.05) anti-inflammatory and antioxidant activity. CONCLUSIONS: The result supports the medicinal uses of the U. staudtii stem bark in the management of pain and inflammatory disease. This is the first report on the biological activities and characterization of compounds inU. staudtii, and presence of protocatechuic acid in Uapaca genus.