Analgesic activities of fractions of Stereospermum kunthianum stem bark.

Abstract

Stereospermum kunthianum (Bignoniaceae) is a woody shrub indigenous to Africa and Asia where the plant parts are used in traditional human medicine for its analgesic properties. We have recently demonstrated the analgesic activity of its aqueous stem bark extract. Vacuum liquid chromatography (VLC) of the methanol extract produced 3 fractions A, B, and C while further column chromatography (CC) analyses of the VLC fractions yielded fractions L, S and Y respectively. The fractions were evaluated for possible analgesic activity using the acetic acid and formalin pain tests. Fractions A,B and C (100, 200, and 400 mg/kg) significantly (p<.0001) inhibited abdominal writhes in mice. While fractions L and Y (100 - 400 mg/kg) significantly (p<.0001) inhibited both phases of the formalin-induced pain in mice with a more intense effect on the late phase than the early phase. Fraction S at the same doses significantly (p<.0001) inhibited both phases but with a more marked effect on the early phase. The results indicate that the VLC and CC fractions of Stereospermum kunthianum may inhibit pain responses mediated via both central and peripherally mechanisms. The present study has confirmed that Stereospermum kunthianum stem bark contains pharmacologically active constituents which possess analgesic activity justifying its popular use in treating painful conditions.