Antidiarrheal activity of aqueous extract of leaves of Euphorbia hirta L.

Abstract

Context: Euphorbia hirta L. is widely distributed in the Indian subcontinent and has many ethnomedicinal uses. Traditionally, the leaves of E. hirta have been used as antidiarrheal agents, for bronchial and respiratory diseases and against conjunctivitis. Aims: To evaluate the antidiarrheal activity of the aqueous extract of leaves of Euphorbia hirta. Methods: Steam and aqueous extracts of leaves of E. hirta were evaluated for their antidiarrheal activity by in vitro antiprotozoal and antimicrobial activity testing, in vivo evaluation of % protection against diarrhea in castor-oil induced rat diarrhea model, gastrointestinal transit and enteropooling assays in rat model and ex vivo tissue contractility studies. Results: Steam and aqueous extracts of leaves of E. hirta demonstrated antiprotozoal activity against Entamoeba histolytica and Giardia lamblia with MICs ranging from 31.25-62.5 µg/mL to 125-250 µg/mL. Both the extracts showed antibacterial activity against Salmonella abony, Escherichia coli and Shigella boydii. In vivo antidiarrheal activity evaluation in castor-oil induced diarrhea model in rats revealed that the steam extract at a dose of 1621 mg/kg body weight (b.w.) produced % inhibition in defecation comparable to loperamide (4 mg/kg b.w.). Aqueous extract produced significant reduction in fecal output when compared to the untreated control group (p<0.05). However, the extracts failed to have any significant effect on the gastrointestinal transit of charcoal meal in rats. Also, gastric fluid accumulation was significantly reduced by steam extract at 2162 mg/kg b.w. and aqueous extract at 100 mg/kg b.w. (p<0.05) when compared to the untreated group. The smooth muscle relaxation produced by the steam extract on the isolated rat ileum was comparable to that produced by atropine (0.05-0.4 µg/mL). Conclusions: The results of this study provide support for the traditional use of Euphorbia hirta leaves as an antidiarrheal agent.