Evaluation of the Antidiarrheal Activity of 80% Methanolic Extract and Solvent Fractions of Calpurnia aurea (Ait.) Benth. (Fabaceae) Roots in Swiss Albino Mice.

INTRODUCTION: In Ethiopian traditional medicine, the roots of C. aurea have been used to treat severe diarrhea. This study is aimed at scientifically validating the antidiarrheal activity of 80% methanol C. aurea root extract and solvent fractions in mice. METHODS: Qualitative phytochemical analysis was performed, and the acute toxicity study was conducted following OECD guideline 423. The antidiarrheal efficacy of the crude extract and solvent fractions was evaluated using castor oil-induced diarrhea, enteropooling, and intestinal motility models. Mice were randomly assigned to five groups: Group I received distilled water (10 mL/kg) and served as the negative control; Group II received either loperamide (3 mg/kg) or atropine sulfate (5 mg/kg) as the positive control; and Groups III-V received 100, 200, and 400 mg/kg of the crude extract or its solvent fractions, respectively. All treatment effects were compared to the negative control. RESULTS: The acute toxicity study confirmed that the crude extract was safe at a limit test dose of 2000 mg/kg. Phytochemical screening test revealed the presence of flavonoids, phenols, tannins, saponins, terpenoids, and alkaloids. In the castor oil-induced diarrhea model, the crude extract at 200 mg/kg (p < 0.01) and 400 mg/kg (p < 0.001) significantly delayed the onset of diarrhea and reduced wet feces. At these test doses, the extract also markedly (p < 0.01) decreased the weight and volume of intestinal contents in the enteropooling test and reduced the peristaltic index (p < 0.01) in the charcoal meal test. Among the solvent fractions, the aqueous fraction produced substantial dose-dependent activity (p < 0.05) at all test doses across all models, with the highest effect at 400 mg/kg (p < 0.001). The ethyl acetate fraction also showed notable effects at 200 mg/kg (p < 0.05) and 400 mg/kg (p < 0.01), whereas the chloroform fraction was active only at 400 mg/kg (p < 0.05). CONCLUSION: The crude extract and solvent fractions of C. aurea roots exhibited statistically significant, dose-dependent antidiarrheal activity. Therefore, these findings support the traditional use of this plant for treating diarrhea.