Abstract

ANTIDIARRHEAL ACTIVITY OF AQUEOUS EXTRACT AND SOME ISOLATED FLAVONOIDS FROM MORINDA MORINDOIDES (BAKER) MILNE-READH. (RUBIACEAE) LEAVES IN ANIMAL MODEL

Mbamu Maya B., Kalonji Ciongo S., Cimanga Kanyanga R.*, Kambu Kabangu O., Vlietinck A. J. and Pieters L.

ABSTRACT

The present study reports the antidiarrheal properties of aqueous extract and its fractions, and some isolated flavonoids from Morinda morindoides leaves assessed against castor oil and magnesium sulfate-induced diarrhea, gastrointestinal motility and castor oil induced-enteropooling in Wistar rats. Results indicated that aqueous extract from M. morindoides leaves and its chloroform, ethylacetate, n-butanol and residual aqueous soluble fractions were found to be able to inhibit castor oil and magnesium sulfate induced-diarrhea in mice when tested at oral doses of 100 and 200 mg/kg bodyweight respectively at different extents. They antidiarrheal effects were characterized by significant reduction level of all diarrheal parameters. Aqueous extract produced 73.0 ± 0.4 and 74.1± 1.4% inhibition of defecation and diarrhea in castor oil test and 70.1 ± 04 and 71.8 ± 0.7% when administered at the highest oral dose of 200 mg/kg body weight. All soluble fractions showed the same effect (% inhibition > 60%) while the detannified extract showed low activity (% inhibition < 50% against defecation and diarrhea). The aqueous extract and its fractions statistically induced significant dose-dependent decrease of the propulsion of the charcoal meal passing through the gastrointestinal tract at administered oral doses of 200 mg/kg body weight with a inhibition percentage from 46.59 to 59.32% compared to untreated group (p < 0.01). They also significantly inhibited castor oil induced-enterepooling in Wistar rats with a percentage inhibition greater than 60%. The isolated flavonoids rutin, quercectrin, quercetin and kaempferol-7-O-rahmnolysophoroside (morindaoside) only inhibit diarrhea-induced by castor-oil (50 < % inhibition < 60% of defecation and diarrhea) and were devoid with significant effect against diarrhea-induced by magnesium sulfate. They also significantly inhibited gastrointestinal motility (45.02 to 58.67%) and castor oil induced-enteropooling in treated animals by producing more than 80% inhibition. This finding clearly showed that tannins and flavonoids are partly responsible for this biological activity. These results show that all selected M. morindoides leaves samples possess interesting antidiarrheal properties which can partly support and justify its current use for the treatment of diarrhea in traditional medicine.

Keywords: Morinda morindoides, Rubiaceae, leaf, aqueous extract, flavonoids, antidiarrheal activity.