Analysis of the gastrointestinal relaxing effect of the stem extract of Gongronema latifolium.

Aqueous extract of the stem of Gongronema latifolium was screened for effects on the gastrointestinal tract of rats and mice. On the isolated rat intestine, the extract (5-80 μg) evoked reproducible and concentration-related relaxation which were attenuated by yohimbine and phenoxybenzamine. Intraperitoneal (i.p.) administration of the extract in mice significantly reduced small intestinal transit dose-dependently. This effect was also attenuated by yohimbine and phenoxybenzamine, but not prazosin and propranolol. Phytochemical analysis revealed the presence of some bioactive constituents, while the i.p. LD(50) value of the extract in mice was established as 1678.63 ± 78 mg/kg. The results suggest the involvement of the alpha(2)-adrenoceptors in the effect of the extract on the intestinal function.