The present study evaluates the anti-nociceptive and anti-inflammatory properties of the aqueous and methylene chloride/methanol (CH2Cl2 / CH3OH) extracts of the stem bark of Croton macrostachyus. The extracts administered orally at the doses of 150, 300 and 600 mg/kg were examined against pain induced by acetic acid, formalin and pressure and against inflammation induced by carragenan, histamine and formalin. Both extracts induced a significant dose-dependent (P < 0.001) reduction in the number of abdominal constrictions induced by acetic acid. The three doses of the two extracts also significantly reduced (P < 0.001) the two phases of pain induced by formalin. At the dose of 600 mg/kg, the aqueous and the CH2Cl2 / CH3OH extracts exhibited a significant analgesic activity against pressure-induced pain. The two extracts also exhibited anti-inflammatory activity, the CH2Cl2 / CH3OH extract being the most active, inhibited acute inflammation induced by carrageenan, histamine and formalin. Both extracts also significantly reduced the chronic inflammation induced by formalin. These results show that the aqueous and CH2Cl2 / CH3OH extracts of the stem bark of Croton macrostachyus possess analgesic and anti-inflammatory properties. These findings are in accordance with the traditional use of the plant and indicate that Croton macrostachyus is a potent source of analgesic and anti-inflammatory principles.
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