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.