Purgative Activity of the Aqueous Leaf Extract of Peninanthus longifolius Miers

Objective: To investigate the claimed purgative property of aqueous leaf extract of Peninanthus longifolius. Materials and methods: Safety profile was evaluated using acute toxicity test (mice). Phytochemical constituents were determined using standard procedures. Effect of extract on the intestinal muscle was studied in isolated guinea pig ileum in the presence and absence of agonists and antagonists. Activity of the extract on intestinal motility was assessed by charcoal meal test (mice) and faecal output determination (mice). Doses of 125, 250 and 500 mg/kg of the extract were used orally. Results: LD₅₀ of the extract of P. longifolius was 3.0 ± 0.85 g/kg. Phytochemical constituents include carbohydrates, proteins, tannins, saponins, alkaloids, steroidal aglycones and glycosides. The extract produced contraction in the guinea pig ileum in a dose-related manner. The contraction was antagonized only by atropine but not by hexamethonium or mepyramine. It also increased intestinal motility and faecal output. Conclusion: Aqueous leaf extract of P. longifolius produced significant (p < 0.05) degree of purgation predominantly through stimulation of cholinergic pathway. This may be attributed to one or more bioactive constituents found in the leaf.