Inhibitory effect of the methanol extract and fractions of <i>Garcinia kola</i> seeds on KCl-induced contractions of isolated guinea pig vas deferens

Abstract

The objective of the study was to investigate the phytochemical constituents and pharmacological effects of fractions of a methanol crude extract of Garcinia kola seed on chemically induced contractions of isolated guinea pig vas deferens. The extract was obtained by Soxhlet extraction with methanol (80% v/v) at 65 ℃ for 25 h. It was then successively fractionated with solvents of different polarities including n-hexane, chloroform, ethyl acetate and acetone respectively. In the same vein, the fractions were tested individually at a pre-determined dose of 0.4 mg/mL alone and in the presence of KCl-induced contraction of an isolated guinea pig vas deferens at a tension of 0.5 g. Each of the fractions was also screened to determine its phytochemical constituents. The results showed that none of the fractions induced contraction of the isolated guinea pig vas deferens at the dose used. All the fractions demonstrated inhibitory action to KCl-induced contraction of the isolated guinea pig vas deferens, with the residual methanol fraction demonstrating the strongest inhibitory action. Nifedipine (8×10^-3 mg/mL), a known calcium channel blocker, expectedly and completely blocked the KCl-induced contraction. The phytochemical screening revealed the presence of cardiac glycosides in all the fractions but the absence of anthraquinones in all. The presence of other phytochemicals including alkaloids, saponins, tannins, flavonoids, steroids and terpenes were separately present in all the fractions. Fractions of a methanol crude extract of Garcinia kola seeds show inhibitory action on KCl-induced contraction of isolated guinea pig vas deferens.

Keywords: KCl; Methanol extract; Vas deferens; Guinea pig; Phytochemical