The methanol (M) extract of the fruit-rind of Picralima nitida
(PN) (Apocynaceae) was tested for its anti-diarrhoeal activity. Like loperamide (3 mg/kg
body weight), a single oral dose of PN-M (375, 750 mg/kg
body weight) produced a significant decrease in the frequency of defecation and severity of diarrhoea. To understand the mechanism of its anti-diarrhoeal activity, its effect was further evaluated on intestinal transit; castor oil-induced intestinal fluid accumulation (enteropooling) and electrolyte concentration in the small intestinal fluid. PN-M produced a decrease in intestinal transit (18.81-21.86%) as compared to castor oil treated animals. Unlike atropine, PN-M significantly inhibited castor oil-induced enteropooling. However it did not alter the electrolyte concentration in intestinal fluid as compared to castor oil treated rats.