The folkloric claim of Musa paradisiaca sap in the management of diarrhoea is yet to be substantiated or refuted with scientific data. Therefore, the aim of the current study was to screen the sap of M. paradisiaca for both its secondary metabolites and antidiarrhoeal activity at 0.25, 0.50, and 1.00 mL in rats. Secondary metabolites were screened using standard methods while the antidiarrhoeal activity was done by adopting the castor oil-induced diarrhoeal, castor oil-induced enteropooling, and gastrointestinal motility models. The sap contained flavonoids, phenolics, saponins, alkaloids, tannins, and steroids while cardiac glycosides, anthraquinones, triterpenes, cardenolides, and dienolides were not detected. In the castor oil-induced diarrhoeal model, the sap significantly (P < 0.05) prolonged the onset time of diarrhoea, decreased the number, fresh weight, and water content of feaces, and increased the inhibition of defecations. Na+-K+-ATPase activity in the small intestine increased significantly whereas nitric oxide content decreased. The decreases in the masses and volumes of intestinal fluid by the sap were accompanied by increase in inhibition of intestinal fluid content in the enteropooling model. The sap decreased the charcoal meal transit in the gastrointestinal motility model. In all the models, the 1.00 mL of the sap produced changes that compared well with the reference drugs. Overall, the antidiarrhoeal activity of Musa paradisiaca sap attributed to the presence of alkaloids, phenolics, flavonoids, and/or saponins which may involve, among others, enhancing fluid and electrolyte absorption through de novo synthesis of the sodium potassium ATPase and/or reduced nitric oxide levels.
