Investigation of the in-vivo and in-vitro Antidiarrheal Activity of the Freeze-dried Extracts of Tylosema Fassoglense (Schweinf.) Torre & Hillc. In Selected Animal Models of Diarrhea

Abstract

Diarrhea is a gastrointestinal disorder characterized by an increase in the frequency of bowel movements, liquidity of stool, and amount of stool with a high mortality rate, especially among under-five children. Current treatment approaches are etiology-based limited by financial constraints and side effects. This study investigated the antidiarrheal activities of the freeze-dried extracts of Tylosema fassoglense (Schweinf.) Torre & Hillc. (TFG) tubers in the selected animal models of diarrhea. Tylosema fassoglense tubers extract were prepared by lyophilization and their antidiarrheal activity evaluated in both in-vivo and ex-vivo experimental models of diarrhea. The antidiarrheal effects of TFG were evaluated in the castor oil-induced diarrhea model. Twenty-five adult Sprague-Dawley rats (n=25) were randomized into the negative control (normal saline), low dose (200 mg/kg), medium dose (400 mg/kg), high dose (800 mg/kg), and positive control (5 mg/kg Loperamide) groups. The fecal diarrheic mass and count produced by experimental animals for the first four hours one after the administration of one ml of castor oil (administered to the respective groups one hour after administration of respective treatments by oral gavage) was determined. The effects on luminal secretion were evaluated in the castor oil-induced enteropooling test. Twenty adult Sprague-Dawley rats were randomized into the negative control (normal saline), medium-dose test (400 mg/kg), high dose test (800 mg/kg), and positive control (5 mg/kg Loperamide) groups administering one ml of castor oil by oral gavage one hour after respective treatment following a 24-hours starvation period with ad libitum access to water. The respective weights of luminal content of the small intestine were determined thirty minutes after castor oil administration and recorded. The effect of extracts on gastrointestinal motility was determined in Phenol red test. Twenty adult Sprague-Dawley rats (n=20) were randomized into the negative control (normal saline), medium-dose test (400 mg/kg), high dose test (800 mg/kg), and positive control (5 mg/kg Loperamide) groups. Neostigmine (0.05 mg/kg i.p.) was administered to each experimental animal thirty minutes after administration of the respective treatments. Phenol red meal (0.5 mg of phenol red dye per ml of 1.5% CMC) was then administered by oral gavage to each rat at a dose of (10 ml/kg) twenty minutes after administration of neostigmine. The amount of phenol red dye retained in the stomach after administration was assayed and determined by spectrophotometry. The effects of different concentrations of TFG (0.5-3.5 mg/ml) on the spontaneous contraction of ten-centimeter jejunal segments isolated from adult New Zealand White Rabbits (n=15) as well as in the presence of 10-5 M acetylcholine, 80 mM KCl, and CaCl2 (0.00003-0.03 M), prazosin, propranolol, methylene blue, L-NAME, and naloxone were evaluated. The experimental data were expressed as Mean ± SEM and analyzed using, one-way ANOVA and Turkey’s posthoc test in cases of significance which was set at p≤0.05 using GraphPad PrismTM suite of statistical software. The TFG extract reduced the fecal mass and count in the castor oil-induced diarrhea (p<0.05). The extract also reduced luminal secretion in the enteropooling assay test (p<0.05). The extract also reduced both gastric emptying and peristaltic rate (p<0.05) possibly via the antagonistic effect on muscarinic receptors. The extracts dose-dependently diminished the spontaneous, acetylcholine, KCl (80 mM), and CaCl2 induced contractions. The spontaneous spasmolytic effects were significantly attenuated by naloxone, methylene blue, and L-NAME but not by adrenergic blockers. The TFG extracts possess significant antidiarrheal activities that are possibly mediated via modulation of nitrous oxide pathway, voltage-gated calcium channels, muscarinic and opioid receptors. These findings, therefore, validate the traditional use of this plant as an antidiarrheal.