Analgesic activity 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 [1]. We have recently reported the analgesic activity of its aqueous stem bark extract [2]. Vacuum liquid chromatography (VLC) technique [3] produced 3 fractions: A, B, and C while further column chromatography (CC) analysis [3] of the VLC fractions yielded fractions L, S and Y, respectively. The fractions were evaluated for possible analgesic activity using the acetic acid [4] and formalin pain [5] tests. Fractions A, B and C (100, 200, and 400mg/kg) significantly (p<0.0001) inhibited abdominal writhes in mice. While fractions L and Y (100–400mg/kg) inhibited both phases of the formalin-induced pain in mice, with a more pronounced effect on the late-phase than the early-phase, fraction S at the same doses 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 peripheral mechanisms. The present study has demonstrated and confirmed that Stereospermum kunthianum stem bark contains pharmacologically active constituents which possess analgesic activity justifying its popular use in treating painful conditions.