Evaluation of the effects of Olea europaea L. subsp. africana (Mill.) P.S. Green (Oleaceae) leaf methanol extract against castor oil‐induced diarrhoea in mice

Objectives Olea europaea L. subsp. africana (Mill.) P.S. Green is widely used in South Africa by traditional medicine practitioners to treat diarrhoea. However, little is known scientifically about this South African species in the treatment of diarrhoea. The main aim of the study therefore was to investigate the antidiarrhoeal effect of the leaf methanol extract of the plant species in mice. Methods The antidiarrhoeal activity of the leaf methanol extract of O. europaea subsp. africana was studied using a castor oil‐induced diarrhoeal test. The antipropulsive activity of the plant extract was also investigated using the charcoal meal transit test. Standard methods were used to investigate the acute toxicity and effect of O. europaea subsp. africana on castor oil‐induced intraluminal fluid accumulation. Results Leaf methanol extract of O. europaea subsp. africana and loperamide, a standard antidiarrhoeal drug, significantly reduced the number of diarrhoeal episodes induced by castor oil, significantly decreased the stool mass, significantly delayed the onset of the diarrhoea and protected the animals against castor oil‐induced diarrhoea. Both O. europaea subsp. africana and loperamide significantly decreased the gastrointestinal transit of charcoal meal and castor oil‐induced intraluminal fluid accumulation in mice. The LD50 value was found to be 3475 mg/kg (p.o.). Conclusions The results obtained suggest that the leaf methanol extract of O. europaea subsp. africana has an antidiarrhoeal property and that, given orally, it may be non‐toxic and/or safe in mice.