Unraveling the multi-faceted role of Rosmarinus officinalis L. (rosemary) and diosmetin in managing gut motility

Ethnopharmacological relevance: Rosmarinus officinalis L. (Rosemary) is a popular herb with reported effectiveness against diarrhea, anxiety and constipation, albeit with limited pharmacological evidence. Aim of the study: The current study was aimed at evaluating the therapeutic potential, possible pharmacological mechanisms of action and active constituents of hydro-ethanolic extract of rosemary (Rs.Cr), as potential antidiarrheal, laxative and anxiolytic agent. Method: Rs.Cr was analyzed through reverse -phase high pressure liquid chromatography (RP-HPLC). Laxative, antidiarrheal, and anxiolytic activities were assessed using in vivo models. Spasmogenic and spasmolytic mechanisms were studied on isolated guinea pig ileum and rabbit jejunum tissues, respectively. Possible role of diosmetin, one of the active constituents of Rs.Cr was also evaluated. Results: RP-HPLC analysis revealed presence of diosmetin, rutin and apigenin in Rs.Cr. Laxative effect was seen at low doses, which was partially reversed in atropinized mice. The spasmogenic mechanism was mediated by cholinergic and histaminergic receptors stimulation. At higher doses, antidiarrheal activity was evident, with reduction in gastrointestinal motility and secretions using charcoal meal and enteropooling assays, respectively. Rs.Cr also showed dose -dependent anxiolytic effect. The antispasmodic mechanisms were mediated by antimuscarinic and K + channel opening -like effect (predominant K ATP -dependent). Diosmetin exhibited antidiarrheal and antispasmodic activities, but spasmogenic effect was not seen. Conclusion: Rosemary leaves have dual antidiarrheal and laxative effects, and as well as anxiolytic activity. In addition, the possible modulation of muscarinic and histaminergic receptors, and K ATP channels show it as potential herb to be explored for irritable bowel syndrome. Diosmetin is possibly one of its constituents that contributes to its antidiarrheal activity.