The Antidiarrheal Activity of Octacosanol is Mediated by the Possible Participation of α2 Adrenoreceptors

Abstract

Senna septemtrionalis (Viv.) H.S. Irwin & Barneby, Fabaceae, is a shrub used for treating asthma, diarrhea, and sore throat. This work evaluated for the first time the vasorelaxant, tracheo-relaxant effect, spasmolytic, and antidiarrheal activity of a dichloromethane extract of the aerial parts of Senna septemtrionalis. The chemical characterization of the plant extract using GC–MS showed that octacosanol was the main component. The antidiarrheal actions of octacosanol (from a supplier) were assessed with the castor oil–induced diarrhea and enteropooling, and the motility test using charcoal. The possible mechanism of action of the antidiarrheal activity exerted by octacosanol was assessed using naloxone, pilocarpine, and yohimbine. Senna septemtrionalis showed antidiarrheal activity (ED50 50 mg/kg, p.o.) but lacked vasorelaxant, tracheo-relaxant, and spasmolytic effects. Octacosanol showed antidiarrheal activity (ED50 0.3 mg/kg) with similar activity to 2.5 mg/kg loperamide. Octacosanol delayed the onset of diarrhea, decreased fluid accumulation, and intestinal transit. Yohimbine (1 mg/kg) reversed the inhibition of intestinal transit shown by octacosanol at 50 mg/kg. A docking study revealed that the mode of action for octacosanol is very similar to the partial agonist of α2-adrenoreceptors. Octacosanol, a main component of S. septemtrionalis, exerts antidiarrheal actions in mice by decreasing intestinal transit with the possible participation of α2-adrenergic receptors.