Anti-diarrhoeal activity of methanol extract of Santalum album L. in mice and gastrointestinal effect on the contraction of isolated jejunum in rats

Abstract

Ethnopharmacological relevance: Santalum album L., namely Sandalwood, honored as "Green Gold", is a traditional Chinese herb which has the effects of anti-diarrhoeal and antibacterial activity. But there is limit scientific study on its activity and mechanism in gastrointestinal disorders.

Materials and methods: in vivo, after intragastric administration, the methanol extract of Sandalwood (SE) (200, 400 and 800 mg/kg) were studied in castor oil-induced diarrhoea mice. By the test of small intestinal hyperfunction induced by neostigmine, SE was studied on gastrointestinal transit including gastric emptying and small intestinal motility. Meanwhile, in vitro, the effects of SE (0.02, 0.05, 0.1, 0.2, 0.3, 0.4 mg/mL) on the isolated tissue preparations of rat jejunum were also investigated. The rat jejunum strips were pre-contracted with acetylcholine (Ach; 10(-6)M), 5-hydroxytryptamine (5-HT, 200 μM) or potassium chloride (KCl; 60 mM) and tested in the presence of SE. In addition, the possible myogenic effect was analyzed in the pretreatment of the jejunum preparations with SE or verapamil in Ca(2+)-free high-K(+) (60 mM) solution containing EDTA.

Results: At doses of 200, 400 and 800 mg/kg, SE showed significant anti-diarrhoeal activity against castor oil-induced diarrhoea as compared with the control. At the same doses, it also inhibited the gastric emptying and small intestinal motility in the mice of which small intestinal hyperfunction induced by neostigmine. It caused inhibitory effects on the spontaneous contraction of rat-isolated jejunum in dose-dependent manner ranging from 0.02 to 0.4 mg/mL, and it also relaxed the Ach-induced, 5-HT-induced and K(+)-induced contractions. SE shifted the Ca(2+) concentration-response curves to right, similar to that caused by verapamil (0.025 mM).

Conclusions: These findings indicated that SE played a spasmolytic role in gastrointestinal motility which was probably mediated through inhibition of muscarinic receptors, 5-HT receptors and calcium influx. All these results provide pharmacological basis for its clinical use in gastrointestinal tract.

Keywords: Cholinergic and calcium antagonist; Diarrhea; Gastric emptying; Intestinal smooth muscle; Small intestinal motility.