Antinociceptive activity of methanol extract and aqueous fraction of the stem bark of Pentaclethra macrophylla Benth (Mimosaceae)

Abstract

The antinociceptive activity of the methanol extract and the aqueous fraction of the bark of Pentaclethra macrophylla, family: (mimosaceae) was evaluated using the acetic acid induced mouse writhing assay and tail immersion assay in mice. The methanol extract and the aqueous fraction at a dose of 50 and 100 mg/kg body weight administered orally exhibited significant inhibition of the acetic acid induced writhing assay in a dose dependent manner (p < 0.001) with 100 mg/kg dose giving a higher inhibition. The methanol extract and the aqueous fraction also showed significant increase in the heat tolerance capacity in mice in a dose dependent manner (p < 0.001) in the tail immersion assay. These findings therefore justify the ethnomedicinal use of P. macrophylla stem bark as an antinociceptive agent.   Key words: Antinociceptive activity, Pentaclethra macrophylla, tail immersion assay, mouse writhing assay, stem bark.