Ethopharmacological Approach, in vivo Antidiarrhoeic Properties of Aqueous Leaf Extract of Mallotus oppositifolium (Euphorbiaceae) and Isolation of Antidiarrheal Compound

Mallotus oppositifolium. Müll. Arg (Euphorbiaceae) is commonly used in the Center Region of Cameroon against diarrheal syndromes and joint pains. In order to provide a scientific basis for its use in the traditional treatment of diarrhea, we proposed to evaluate the effects of aqueous extracts of the leaves of this plant on the characteristic patterns of diarrhea. The ethnopharmacological approach was carried out in Gouifé village in Bafia (Cameroon) by observing traditional therapeutic practices and by the interview of 5 traditional therapists and 11 of their patients about the traditional treatment of diarrheal syndromes. The leaf extracts of M. oppositifolium was extracted by decoction and the product at the doses of 31.25, 62.50 and 125 mg/kg body weight was tested in vivo on castor oil-induced secretory and motor diarrhea in rats, using standard antidirrhea techniques. The diarrhea was induced in the rats using standard inducing procedure. The decoction leave extract were found to act against castor oil-induced secretory diarrhoea in rats as it increased significantly the time to onset of diarrhoeal stools in a dose-dependent manner at all the doses investigated (p < 0.01) compared to animals who received distilled water. The mass and volume of intestinal contents, compared with Loperamide (36.80%) and distilled water 52.50% (p < 0.05), decreased significantly by 9.70% and 32. 60% at 32.25 mg/kg, 38.80% (p < 0.01) and 49.80% (0.05) at 62.5 mg/kg and 28.90% (p < 0.05) and 37.30% at 125 mg/kg, respectively. The decoction extract was also active against motile diarrhea as it increased significantly the time to onset of charcoal-stained diarrheal stools.  Compared to distilled water (70 min), 80 min (p < 0.05), 118 min (p < 0.01) and 207 min (p < 0.01) for the extract doses of 32.25, 62.50 and 125 mg/kg animal weight respectively. The mass and the frequency of the stool output were reduced significantly by all the doses of the extract used in this study. This extract slowed fecal progression by 81.80%, 76% (p < 0.05) and 72% (p < 0.01) at 32.25, 62.5 and 125 mg/kg respectively.  A chemical fractionation by separation and purification using various chromatographic methods (column chromatography, thin layer chromatography, "flash" Chromatography on silica gel G60…) of M. oppositifolium leaves extract with dichloro methane/ methanol revealed the presence of metabolites such as sterols, quercetin, diosmetin, quercitrin. Some of these components have known antidiarrheal properties that would justify the traditional use of the plant in the treatment of diarrhea.