Abstract

The aqueous-methanolic leaf extract and fractions of the Rumex vesicarius L. (Rv.Cr) was evaluated for the possible presence of spasmogenic and spasmolytic constituents to rationalize its traditional uses in gastrointestinal disorders. In rabbit jejunum, R. vesicarius caused a dose-dependent (0.03 to 0.3 mg/ml) weak stimulatory effect on spontaneous contractions, followed by relaxation at the next higher dose (1 mg/ml). In the presence of atropine (0.03 µM), the spasmogenic effect was abolished and the relaxant effect was obtained at lower doses (0.1 to 1.0 mg/ml) shifting the dose response curves to the left. The spasmolytic effect on the spontaneous and K⁺-induced contractions in atropinized preparations was mediated at doses 0.03 to 1.0 mg/ml and 0.3 to 5 mg/ml, respectively which explained the involvement of calcium channel blocking (CCB) effect. The CCB effect was confirmed when pretreatment of the tissue with R. vesicarius produced a dose-dependent shift in the Ca⁺⁺ dose-response curves to the right in a similar manner as verapamil. Activity-directed fractionations revealed that the spasmolytic effect was concentrated in methanolic fraction, while spasmogenic activity in the aqueous fraction which was remarkably stronger than aqueous-methanolic extract. This data shows that the crude leaf extract of R. vesicarius L. contains spasmogenic and spasmolytic constituents mediating their effect through cholinergic and CCB actions, respectively, which explains its traditional use in the gastrointestinal disorders such as abdominal colics and cramps, constipation and diarrhea, gestroesophagial reflux disease and irritable bowel syndrome/inflammatory bowel disease.

Key words: Rumex vesicarius Linn, spasmogenic, Spasmolytic, Cholinergic, CCB.