Presence of cholinomimetic and calcium channel blocking constituents in Carthamus oxycantha

The crude extract of Carthamus oxycantha (Co.Cr) was studied in vitro for its possible spasmogenic and spasmolytic activities. Segments of isolated rabbit jejunum 2-3 cm long were mounted in Tyrode’s solution and aerated with 95% oxygen in carbon dioxide. Isotonic responses were measured on Bioscience oscillograph. Isotonic responses were measured on Bioscience oscillograph. Co.Cr caused dose-dependent (0.03-3.0 mg/mL) spasmogenic effect in spontaneously contracting rabbit jejunum, followed by relaxation at the next higher doses of 5.0-10.0 mg/mL. In the presence of atropine (0.03 µM), spasmogenic effect was blocked and the relaxant effect was observed at lower doses (0.03-5.0 mg/mL). Co.Cr (1.0-10.0 mg/mL) produced relaxation of high K+ (80 mM)-induced contraction, suggestive of calcium channel blockade. The CCB effect was confirmed when Co.Cr in the atropinized tissue produced a dose-dependent shift in the Ca++ dose-response curves to the right, similar to that of verapamil, a standard calcium channel blocker. These data indicate that Carthamus oxycantha exhibits spasmogenic effect through cholinergic action and the spasmolytic effect through calcium channel blockade.