Preliminary Evaluation of the Antidiarrheal Effects of Ethanol Leaf Extract and Fractions of Rauwolfia vomitoria Afzel. (Apocynaceae)

Abstract

Context: Diarrhea, a major leading cause of death among under-five children in developing countries is still ravaging the society today due to limitations associated with conventional treatment approaches. The leaf of Rauwofia vomitoria ( R. vomitoria ) is used by the locals in Nigeria for the treatment of diarrhea. Aim: This study evaluated the anti-diarrheal activity of the leaf extract and fractions of R. vomitoria using animal models. Methods: Phytochemical screening of the extract was carried out. The extracts and fractions of R. vomitoria were screened using castor-oil induced diarrhea, castor-oil induced enteropooling, charcoal meal test and ex-vivo anti-spasmomodic models. The tests groups received 400 mg/kg of the extract, n-hexane, ethyl acetate and water fractions based on the result of preliminary study. The Negative control (5 ml/kg of 5% Tween-80) and Positive control (Loperamide, 2 mg/kg and atropine sulphate, 10 mg/kg) were used. Ex-vivo anti-spasmodic test was carried out using isolated guinea pig ileum. Results: Phytochemical test revealed the presence of alkaloids, saponins, tannins, flavonoids, cardiac glycoside, terpenoids and steroids. In castor oil-induced diarrhea model, 400 mg/kg of the extract and fractions significantly (p≤0.05) prolonged diarrhea onset, decreased frequency of defecation, weight of feces, and volume of intestinal content. The extract and n-hexane fraction produced more significant (p<0.05) antidiarrheal activity in castor oil –induced enteropooling and charcoal meal test models. The extract exhibited a dose dependent inhibition of acetylcholine induced contraction of isolated ileum. Conclusion: Results obtained from this study validate the folkloric use of R. vomitoria leaf extract in the treatment of diarrhea.