Anti-diarrhoeal action of a pycnocycla spinosa extract in comparison with loperamide and dicyclomine

H. Sadraei, G. Asghari & M. Shams, Department of Pharmacology, School of Pharmacy and Pharmaceutical Sciences, Isfahan University of Medical Sciences, Isfahan, Iran.

Previous studies have shown that an aqueous alcohol extract of Pycnocyclaspinosa (P. spinosa) has anti-spasmodic and anti-diarrhoeal activities (Sadraei et al., 2003). The aim of this study was to further investigate the anti-diarrhoeal action of P. spinosa extract and its effects on small intestinal transit, in comparison with two reference drugs loperamide and dicyclomine.

A 70% ethanol extract of the aerial part of P. spinosa was prepared by a percolation method (Samuelsson, 1999). Male NMRI mice (25-30g; Pasture Institute, Tehran), fasted overnight with free access to water, were treated with the P. spinosa extract, loperamide, dicyclomine or vehicle (p.o.). Thirty minutes later, castor oil (0.5ml) was given orally to the animals. In another group of animals, MgSO4 (0.5ml of a 10% solution) was given and half an hour later the extract or the drugs were administered. The onset and number of wet defecations were recorded for each animal for 2.5 hours after treatment with the diarrhoea inducing agent. In another group of animals, the intestinal transit of a charcoal meal (1ml of 3% charcoal in 10% aqueous tragacanth) was determined following administration of the extract, loperamide, dicyclomine or vehicle. Diarrhoea was scored as the number of watery defecations. Small intestinal transit was expressed as % distance that the charcoal moved over 30 minutes, relative to whole length of small intestine.

The P. spinosa extract delayed the onset of diarrhoea and significantly reduced the wet defecation induced by castor oil and MgSO4 (Table 1). The extract, at a dose of 1mg/kg, had an anti-diarrhoeal effect similar to loperamide (2mg/kg) and, at a dose of 0.5mg/kg, its anti-diarrhoeal action was greater than that of dicyclomine (5mg/kg) (Table 1). Unlike dicyclomine, the P. spinosa extract significantly reduced the small intestinal transit of the charcoal meal. However its inhibiting effect on intestinal transit was less than that of loperamide (Table 1).

Table 1: Effect of an alcohol extract of P. spinosa, loperamide or dicyclomine on diarrhoea induced by castor oil and MgSO4, and on intestinal transit of charcoal.

Results are expressed as mean ± s.e.mean (n=10 for each group) and compared with the control group using the unpaired Student’s t-test (*P<0.05, **P<0.01, ***P<0.001).

This study shows that the anti-diarrhoeal effect of the P. spinosa extract is similar to that of loperamide. Inhibition of intestinal propulsion is the most likely mechanism that could account for the anti-diarrhoeal activity of the extract.

Sadraei , H. et al., (2003). Phytother. Res., 17(6): 645-649.
Samuelsson, G. (1999). Drugs of Natural Origin. 4th ed. Stockholm.