Bioassay-Guided Evaluation of Anti-Diarrhoeal Activity of Sweet Potato Leaf Extracts

Diarrhoea is a global health issue affecting all regions and populations, particularly in low and middle-income countries of sub-Saharan Africa and Asia from where the very young and old aged are more vulnerable. The conventional belief that extracts of sweet potato leaves are effective in the treatment of diarrhoea is not supported by any statistical evidence from the scientific community. Therefore, the present study aimed to screen the crude extracts of sweet potato for its secondary metabolites, acute toxicity, antioxidant enzyme, and antidiarrhoeal activity at 125, 250, and 500 mg/kg bw in a Wistar rat model. Methanol and n-hexane extracts of sweet potato (Ipomoea batatas) leaves were tested for antidiarrhoeal activity using castor oil-induced models in rats. The most active extracts were screened for elemental compositions using standard methods. The crude extracts revealed the presence of flavonoids, saponins, alkaloids, tannins, and terpenes. The LD50 of the extracts was found to be greater than 5000 mg/kg body weight of the rats. The elemental analysis of the most active extract revealed the presence of zinc (Zn), potassium (K), sodium (Na), and chloride (Cl). Both extracts delayed diarrhoea onset and reduced faecal frequency and water content significantly (p<0.05), with the methanol extract showing greater inhibition (~66.5%) at 500 mg/kg compared to controls. Na+-K+-ATPase, alkaline phosphatase, and catalase activity in the small intestine increased significantly (p < 0.05) as the dose of crude extracts increased, whereas crude extract produced dose-specific dependent on intestinal superoxide dismutase activity and nitric oxide concentration. The GC-MS analysis carried out on the most active extract revealed that the extract is composed of gallo-tannins (71.27%), n-Hexadecanoic acid (23.53%), catechol (2.57%), methylgallate (1.59%), propanoic acid, 2-(aminoxy) (0.92%), and trigonelline (0.10%). These compounds were found to be the most abundant in the extract.