Phytochemical Screening and Antidiarrhoeal Activity of Psidium guajava Leaf Extracts in Wistar Rats: A Case Study from Osun State

Diarrhoeal diseases remain among the most common causes of childhood morbidity in rural Osun State, South West Nigeria, where community reliance on guava leaf decoctions for the management of acute diarrhoea is well established. This study investigates the phytochemical constituents and antidiarrhoeal activity of aqueous and ethanolic leaf extracts of Psidium guajava in Wistar rats. Leaf samples were obtained from homestead gardens in Osogbo, shade-dried, and extracted by cold maceration. Phytochemical screening was performed using standard methods. Antidiarrhoeal activity was evaluated using castor oil-induced diarrhoea, charcoal meal transit, and castor oil-induced enteropooling models in rats divided into five groups: extract doses (200 and 400 mg/kg), standard drug (loperamide 5 mg/kg), and negative control (saline). The frequency of diarrhoeal stools, onset time, and intestinal transit rate were measured. Phytochemical analysis detected tannins, flavonoids, saponins, alkaloids, and phenolic acids. Both extracts significantly reduced the number of diarrhoeal stools and intestinal transit rate in a dose-dependent manner, with the ethanolic extract demonstrating superior activity. Enteropooling was significantly reduced at the 400 mg/kg dose of both extracts. Tannins and flavonoids were implicated as the likely active constituents. These findings provide a scientific basis for the traditional use of guava leaves in diarrhoea management in South West Nigeria. Keywords: Psidium guajava, antidiarrhoeal, castor oil model, Osun State, phytochemical