Antidiarrheal and Spasmolytic activity of Calendula arvensis Linn in laboratory animal models — the potential role of calcium channel blockade

Albeit the advancement in the pharmaceutical industry, herbal-based medicine remains the most widely used form of medicine worldwide. The present study was conducted to determine the toxicological profile, antidiarrheal and spasmolytic activities of the hydroalcoholic Calendula arvensis Linn flower extract. The toxicity study revealed LD50 of Cal extracts (CalE) was 2450 mg/kg. Utilizing castor oil-induced diarrhea models and enterpooling assessment revealed that CalE has a potent antidiarrheal effect. Employing the "Gastrointestinal Motility test" using a charcoal meal confirms the reduction of intestinal peristaltic movement. Oscillograph studies revealed that CalE inhibits intestinal motility in a concentration-dependent manner. CalE did not act on the muscarinic receptors or nicotinic receptors. CalE did not act on both α and β adrenergic receptors as it has no effect on the duodenum in the presence of α adrenergic blocker (Prazosin) and α and β adrenergic receptor blocker (Propranolol). Interestingly, in the presence of CaCl2, CalE exerted an inhibitory effect on the motility of the duodenum, similar to the effect of verapamil and in dose-dependent manner. Thus, this data indicates that CalE exhibits antidiarrheal and spasmolytic activities through calcium channel blockade.