Anti-diarrhoeal effect of methanol leaf fraction of Cola hispida Brenan and Keay in rats

Abstract

Purpose: To evaluate the anti-diarrhoeal activity of 20 % methanol leaf fraction of Cola hispida (MLFC) using castor oil-induced diarrhoea model in rats. Methods: The activity of MLFC against castor oil-induced diarrhoea, intestinal fluid accumulation (enteropooling), and gastrointestinal motility were evaluated. The experimental animals were grouped into five, each with four animals. Group 1 received distilled water, while group 2 received loperamide and served as negative and standard control groups respectively. Groups 3 - 5 were administered 200, 400 and 600 mg/kg of MLFC respectively. One-hour post-treatment, castor oil (p.o.) was used to induce diarrhoea in all the groups. The activity of MLFC was tested against castor oil-induced looseness of stool, fluid accumulation in the intestine and intestinal motility of charcoal meal. Its effect on electrolyte concentration in the small intestinal content was assessed; furthermore, its effect on the electrolyte concentrations of Na+, Cl-, K+, and HCO3-  in supernatants obtained from the intestinal loop effluents of the rats was evaluated. Results: The MLFC produced a significant (p < 0.05) and dose-dependent decrease in the severity of diarrhoea and frequency of watery stool passed in castor oil-induced diarrhoea, enteropooling, gastrointestinal transit of charcoal meal in rats and serum concentrations of sodium and chloride ions, while significant (p < 0.05) increase in potassium and bicarbonate ion concentrations were observed when compared with diarrhoeal control group. Similar inhibitory effects were obtained for loperamide control group. Conclusion: The results of the study indicate that methanol leaf fraction of Cola hispida possesses anti-diarrhoeal properties by inhibiting intestinal peristalsis and hypersecretion of water and electrolytes. Thus, the findings lend some support to the traditional use of the plant for the treatment of diarrhoea.