George K. Ainooson

Antiarthritic and antioxidant effects of the leaf extract of Ficus exasperata P. Beauv. (Moraceae)

Leaf extracts of Ficus exasperata P. Beauv. (Moraceae) are commonly used in Ghanaian traditional medicine for the treatment of several pathological states including inflammatory disorders. The present study was undertaken to evaluate the antiarthritic effect of an ethanolic extract of F. exasperata (FEE) in the Freunds adjuvant-induced arthritis model in rats. Since free radicals and reactive oxygen species are implicated in inflammatory joint diseases such as rheumatoid arthritis, the antioxidant potential of the extract was investigated in in vitro experimental models. FEE as well as the positive controls, dexamethasone and methotrexate, showed significant dose-dependent antiarthritic properties when applied to established adjuvant arthritis. Oral administration of FEE (30–300 mg/kg p.o.) significantly reduced the arthritic edema in the ipsilateral paw of rats with a maximal inhibition of 34.46 ± 11.42%. FEE (30–300 mg/kg p.o.) also significantly prevented the spread of the edema from the ipsilateral to the contralateral paws indicating inhibition of systemic spread. The disease-modifying antirheumatic drug methotrexate (0.1–1 mg/kg i.p.) and the steroidal anti-inflammatory agent dexamethasone (0.3–3 mg/kg i.p.) also reduced very significantly the total polyarthritic edema as well as the spread of the arthritis from the ipsilateral to the contralateral paws of the treated animals. The extract also exhibited reducing activity (EC50 = 8.105 ± 18.49), scavenged 2,2-diphenyl-1-picrylhydrazyl (DPPH, EC50 = 0.499 ± 0.302) and prevented lipid peroxidation (IC50 = 1.283 ± 0.923) in rat brain homogenates. Phenols were detected in the extract. These results suggest that ethanolic extract of the leaves of F. exasperata exerts antiarthritic activity after oral administration and also has antioxidant properties which may contribute to its activity.

Analgesic effects of stem bark extracts of Trichilia monadelpha (Thonn.) JJ De Wilde.

Objectives: Various parts of Trichilia monadelpha (Thonn) JJ De Wilde (Fam. Meliaceae) are used in Ghanaian traditional medicine for the treatment of painful and inflammatory conditions. The present study examined the analgesic properties of the petroleum ether (PEE), ethyl acetate (EAE), and the hydro-ethanolic (HAE) extract of the stem bark of the plant in murine models. Materials and Methods: PEE, EAE, and HAE were assessed in chemical (acetic acid-induced abdominal writhing and formalin tests), thermal (hot plate test), and mechanical (Randall-Selitto paw pressure test) pain models. The possible mechanisms of the antinociceptive action were also examined with various antagonists in the formalin test. Results: HAE, EAE, and PEE, each at doses of 10–100 mg/kg orally, and the positive controls (morphine and diclofenac) elicited significant dose-dependent antinociceptive activity in the chemical (acetic acid abdominal writhing and formalin tests), thermal (hot plate test), and mechanical (Randall-Selitto paw pressure test) pain models in rodents. The antinociceptive effect of HAE was partly or wholly reversed by systemic administration of atropine, naloxone, and glibenclamide. The antinociceptive effects of EAE and PEE were inhibited by atropine. Conclusion: The extracts HAE, EAE, and PEE caused dose-related antinociception in chemical, thermal, and mechanical models of pain in animals. The mechanism of action of HAE involves an interaction with muscarinic cholinergic, adenosinergic, opioidergic pathways, and ATP-sensitive K+ channels while that of EAE and PEE involve the muscarinic cholinergic system.