Abstract

Department of Pharmaceutical Chemistry, University of Benin, Benin city, Nigeria. Department Pharmacology, Niger-Delta University, Wilberforce Island, Yenagoa, Nigeria.

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.