The stem bark of Khaya senegalensis A. Juss (Meliaceae) is used traditionally in the treatment of malaria, intestinal worms, diarrhea, dysentery and venereal diseases. Despite the claim as an effective antidiarrheal remedy in both humans and animals, there is scarcity of documented scientific information of specific in vivo antidiarrheal test using extracts of this plant. The number of wet feces and the distance travelled by activated charcoal meal in rats orally given 300, 600 and 1200 mg/kg doses of aqueous and ethanolic extracts of the stem bark of K. senegalensis were evaluated in the castor oil induced diarrhea and gastrointestinal motility studies. The phytochemical constituents and acute toxicity test of the extracts were also tested using standard methods. Both extracts dose-dependently (P<0.05) reduced diarrhea induced by castor oil in rats, but did not significantly decrease (P>0.05) distance travelled by charcoal in the gastrointestinal motility test. The extracts were apparently safe at 2000 mg/kg body weight per os. Cardiac glycosides and flavonoids were present in both extracts, while tannins were present only in the ethanolic extract. The aqueous and ethanolic stem bark extracts of K. senegalensis inhibits diarrhea, at least in part, by a mechanism other than inhibition of gastrointestinal motility. The antidiarrheal activity of K. senegalensis may be attributed to the flavonoid and tannin constituents present in the extracts. The ability of K. senegalensis to significantly protect against castor oil induced diarrhea justifies its use in traditional management of human and animal diarrhea.

Key words: Antidiarrheal activity, Castor oil, Khaya senegalensis, Phytochemical constituents