Antidiarrhoeal Potentials of Methanol Fraction of Napoleona Imperialis on Castor Oil-Induced Diarrhoeal Albino Rats

Abstract

Napoleona imperialis is used traditionally in the treatment of diarrhoea. This study was therefore undertaken to examine the anti-diarrhoeal properties of methanol fraction of Napoleona imperialis on castor oil induced diarrhoeal albino rats using different experimental models. Anti-diarrhoeal effect was evaluated by castor oil induced diarrhoeal test/defecation test, gastro-intestinal motility or charcoal meal test and gastro-enteropooling test. In the acute toxicity studies of Napoleona imperialis extract, there was no sign of toxicity up to 5000 mg/kg body weight. The qualitative phytochemical analysis showed the presence of high amount of phenolics, alkaloids, flavonoids; moderate amounts of glycosides, and little quantities of steroids, tannins and terpenoids. The quantitative phytochemical screening revealed in decreasing order of abundance the following constituents: Total phenolics (4672.04±44.00 mg/100g) > flavonoids (371.33±1.04 mg/100g) > alkaloids (339.17±17.00 mg/100g) > glycosides (64.69±2.72 mg/100g) > terpenoids (16.16±0.20 mg/100g) > tannins (9.32±1.70 mg/100g) > steroids (0.21±0.04 mg/100g). In the defecation test, a significant (p ˂ 0.05) reduction in the mean number of diarrhoeal faeces was observed in the group treated with 150 mg/kg b. w. There was also a significant (p ˂ 0.05) reduction in the mean number of wet faeces when treated with the standard drug, loperamide. However there was a non-significant (p > 0.05) reduction in the number of wet faeces when treated with 300 mg/kg and 600 mg/kg body weight of the fraction. There was an inverse effect of the fraction on castor oil induced diarrhoea. The percentage inhibition of diarrhoeal faeces at 150, 300 and 600 mg/kg b. w were 86.67 %, 53.33 % and 26.67 % respectively. The standard drug, loperamide showed a 73.33 % inhibition of diarrhoeal faeces. The mean values of total defecation produced in group 1 to 5 were also investigated. Here the 20% methanol fraction of Napoleona imperialis showed a no significant difference when groups 3 to 5 are compared with the control. In gastrointestinal motility test, the fractions showed a non-dose dependent decrease in the distance travelled by the charcoal meal compared to group 1 (negative control). The fraction of Napoleona imperialis significantly (P ˂ 0.05) decreased the propulsion of charcoal meal in rat gastrointestinal tracts of rats by 68.90 ± 5.74 % at 300 mg/kg and 74.12±3.06 at 600 mg/kg compared to the negative control (90.14 ± 6.73 %). A similar significant (P ˂ 0.05) reduction in the gastrointestinal transit of charcoal meal in rats was achieved with the reference drug, loperamide (65.51 ± 15.40 %). There was no significant (p ˃ 0.05) difference between the distances travelled by charcoal meal in the groups treated with the different doses of the fraction when compared to the group treated with standard drug, loperamide (group 2). The standard control group, the treated groups (150 mg/kg, 300 mg/kg and 600 mg/kg) showed 27.32 %, 10.40 %, 23.56 % and 17.77 % inhibitions in the distance travelled by charcoal meal respectively compared to the negative control (group 1). In gastro-enteropooling studies, the fraction showed a non-significant (p > 0.05) decrease in the weight and volume of the intestinal content in a non-dose dependent manner when compared to the negative control (group 1). The Aqueous methanol fraction of Napoleona imperialis exhibited antidiarrhoeal properties by inhibiting gastro-intestinal motility, enteropooling, wetness and frequency of defecation. This could be as a result of the action of some of the components present in Napoleona imperialis