Background: The fruit of Rosa moschata has traditionally been used for the treatment of abdominal spasm and diarrhoea. Therefore, the aim of this study was to investigate mechanism(s) responsible for its medicinal use in gut spasm and diarrhea.
Methods: Hydro-methanolic extract of Rosa moschata (Rm.Cr) was studied in isolated rabbit's jejunal preparations for possible antispasmodic activity. Based upon in vitro relaxant activity in isolated gut preparations, in vivo antidiarrheal activity was carried out in mice to confirm its antidiarrheal effect. Acute toxicity study was performed to determine safe dose range before in vivo experiments.
Results: In isolated rabbits' jejunal preparations, Rm.Cr inhibited the spontaneous and high K+-induced contractions with respective EC50 values of 0.66 (0.44-0.97; n = 5) and 2.28 mg/mL (1.43-3.62; n = 5), like that of verapamil. This suggests the presence of calcium channel blocking (CCB) activity as a possible mode of action. The Ca++ channel blocking activity was further confirmed when pre-treatment of isolated jejunums with Rm.Cr (1-5 mg/mL) caused a rightward shift in the Ca++ concentration-response curves (CRCs), similar to verapamil. Rm.Cr was safe up to 2000 mg/kg for in vivo acute toxicity. Rm.Cr provided 55% and 80% protection from diarrhoea in respective doses of 100 mg/kg and 1000 mg/kg. These data indicates that the crude extract of Rosa moschata possesses Ca++ antagonist-like constituent(s), which explains its inhibitory effect on gut motility; a mechanism that underlies its antidiarrheal and antispasmodic activities.
Conclusion: The study shows that the crude extract of fruits of Rosa moschata possesses antispasmodic effects mediated possibly through voltage gated Ca++ channel blockade, which provides sound pharmacological base to its medicinal use in gut spasms and diarrhoea, though additional mechanism(s) cannot be ruled out.