Studies on prokinetic, laxative, antidiarrheal and gut modulatory activities of the aqueous-methanol extract of Celtis africana and underlying mechanisms

This study describes the prokinetic, laxative and antidiarrheal activities of the aqueous-ethanol extract of Celtis africana (Ca.Cr) in mice, together with gut stimulatory and inhibitory activities using isolated gut preparations in an attempt to explore possible mechanisms of action. Ca.Cr, showed atropine-sensitive prokinetic and laxative activities in mice at low doses (30 and 100 mg kg^-1), followed by antidiarrheal effect at next higher doses (300 and lOOOmg kg^-1). In spontaneously contracting rabbit jejunum, Ca.Cr, showed a dose-dependent (0.03-3 mg mL^-1) spasmogenic effect followed by spasmolytic effect at higher concentrations (5-10 mg mL^-1). Activity-directed fractionation revealed that the atropine-sensitive spasmogenic component was concentrated in the aqueous fraction, while the spasmolytic component was separated in the organic fraction. When studied against the high K⁺ (80 mM)-induced contractions, both Ca.Cr and Ca.Cl caused dose-dependent (0.01 -5.0 mg mL^-1) inhibition, later being more potent, while both shifted the Ca⁺⁺ concentration response curves to the right, similar to verapamil. These data showed that the crude extract of C. africana possesses prokinetic, laxative and spasmodic activities mediated through muscarinic receptor activation concentrated in the aqueous fraction while, antidiarrheal and spasmolytic activities via Ca⁺⁺ antagonist activity, separated in the chloroform fraction.