The Journal of Phytopharmacology 2026; 15(3):203-210 ;   DOI:10.31254/phyto.2026.15301

Research Article

Evaluation of the antidiarrheal effects of freeze-dried bark extract of Warburgia ugandensis in experimental animals

Rugut C. Kiprop¹ , Charles G. Githinji^1,2 , Anne W. Murithi¹

Rugut C. Kiprop,Charles G. Githinji,Anne W. Murithi

1. University of Nairobi, Department of Human Anatomy and Medical Physiology, Faculty of Health Sciences. P.O Box 30197-00100, Nairobi, Kenya
2. Center for Bioequivalence Studies and Pharmaceutical Research, University of Nairobi. P.O Box 30197-00100, Nairobi, Kenya

*Author to whom correspondence should be addressed.

Received: 9th January, 2026 / Revised: 24th June, 2026 / Accepted: 23rd May, 2026 / Published : 24th June, 2026

Abstract

---

Background: Diarrheal diseases remain a major global public health concern and are an important cause of morbidity and mortality, especially among children. Current therapies for diarrhoea management are often limited by poor availability, low acceptability, and adverse effects. Traditional herbal remedies such as Warburgia ugandensis, widely used in African traditional medicine, may provide a useful alternative. Objective: To investigate the antidiarrheal effects of freeze-dried bark extract of W. ugandensis and explore its possible mechanism of action.  Materials and Methods: Freeze-dried bark extract of W. ugandensis was prepared and evaluated using experimental animal models. Thirty rats were randomly assigned to six groups (n=5): negative control (normal saline, 5 mL/kg), positive control (loperamide, 5 mg/kg), and four test groups receiving extract doses of 200, 400, 800, and 1200 mg/kg orally. Diarrhoea was induced using castor oil, and faecal output was monitored for 6 h. Intestinal motility was assessed using the charcoal meal test, while antisecretory activity was evaluated by prostaglandin E-induced enteropooling. The effect on smooth muscle contractility was studied using isolated rabbit jejunum preparations. To investigate the mechanism of action, tissues were pretreated with tamsulosin (α-antagonist), yohimbine (α-antagonist), propranolol (β-antagonist), naloxone (opioid antagonist), and acetylcholine before administration of the extract.  Results: The extract reduced faecal output in a dose-dependent manner, with significant inhibition observed at 800 mg/kg (p<0.01). In the charcoal meal test, the same dose significantly reduced intestinal transit (p<0.001). The extract also significantly inhibited prostaglandin E₂-induced intestinal fluid accumulation (p<0.001). In isolated rabbit jejunum, the extract produced a dose-dependent reduction in the force of spontaneous contractions up to 5.0 mg/mL. The relaxant effect of 1.0 mg/mL extract was attenuated by acetylcholine, tamsulosin, yohimbine, and naloxone, but was unaffected by propranolol. Conclusion: Freeze-dried bark extract of W. ugandensis exhibited significant antidiarrheal activity through inhibition of intestinal motility and secretion. Its antimotility effect may involve activation of α-adrenergic and µ-opioid receptors, supporting its traditional use in the management of diarrhoea.

Keywords

W. ugandensis, Antidiarrheal activity, Castor oil-induced diarrhea, Intestinal motility, Enteropooling assay, Traditional medicine

---