Anti-diarrhoeal Activity of Psidium guajava Leaf Extract in Laboratory Rats: A Pharmacological Evaluation

Diarrhoeal diseases represent a significant cause of morbidity and mortality in livestock and companion animals in Nigeria, particularly in resource-limited settings where access to conventional therapeutics is restricted. Psidium guajava, the guava plant, is widely distributed across Nigeria including the South South and South East zones, and its leaves have been traditionally used to manage diarrhoea in both humans and animals. This study evaluated the anti-diarrhoeal activity of aqueous and ethanolic leaf extracts of Psidium guajava in Wistar rats using castor oil-induced diarrhoea and charcoal meal gastrointestinal transit models. Forty rats were divided into five groups: normal saline control, loperamide positive control at 3 mg/kg, aqueous extract at 400 mg/kg, ethanolic extract at 400 mg/kg, and ethanolic extract at 800 mg/kg. The onset of diarrhoea, number of wet faeces, and charcoal meal transit distance were recorded over four hours. Both extracts significantly reduced the frequency of wet faeces and delayed the onset of diarrhoea compared with the control group. The ethanolic extract at 800 mg/kg was most effective, reducing wet faeces by 71.3 percent. Charcoal transit was significantly inhibited by both extracts, suggesting an intestinal motility-reducing mechanism. Phytochemical analysis revealed the presence of tannins, flavonoids, and alkaloids which may contribute to the observed effects. These results validate the traditional use of guava leaves in managing livestock diarrhoea and support further investigation of its active constituents. Keywords: Psidium guajava, anti-diarrhoeal, gastrointestinal, castor oil, extract.