Evaluation of Antidiarrheal Activity of 80% Methanol Extract and Solvent Fractions of the Leaves of Withania somnifera (L.) Dunal in Swiss Albino Mice

Background. Withaniasomnifera is an important medicinal plant for the treatment of diarrhea in Ethiopian folklore medicine. The aim of this study was to evaluate the antidiarrheal activity of Withania somnifera leaves in Swiss albino mice. Materials and Methods. Hydromethanolic crude extraction and solvent fractionation were done using cold maceration technique. 80% methanol was used as a solvent in crude extraction, while distilled water, n-butanol, and chloroform were employed during fractionation. Castor oil-induced diarrhea, enteropooling, and gastrointestinal motility models were employed to evaluate antidiarrheal activity. Mice were randomly divided into five groups (six mice per group): negative control, which received 2% Tween 80 in distilled water; positive control, which received 3 mg/kg loperamide; and three test groups (III, IV, and V), which were treated with 100 mg/kg, 200 mg/kg, and 400 mg/kg of crude extract and solvent fractions, respectively. Results. The crude extract, aqueous, and n-butanol fractions significantly delayed the onset of diarrhea at 200 mg/kg and 400 mg/kg dose. There was a significant reduction in the number and weight of stools at all tested doses of the crude extract and aqueous fraction, and at 200 mg/kg and 400 mg/kg of n-butanol fraction. Significant reduction in volume and weight of intestinal contents was observed at all tested doses of the crude extract, and at 200 mg/kg and 400 mg/kg of aqueous and n-butanol fractions. All tested doses of the crude extract and 200 mg/kg and 400 mg/kg of the aqueous and n-butanol fractions significantly reduced the motility of charcoal meal. Conclusion. This study demonstrated that the crude extract and solvent fractions of the Withania somnifera leaves have antidiarrheal activity and supported the folklore use of the plant.