Study of effects on dihydropiridine receptor of furanosequiterpenes from Ligularia virgaurea

OBJECTIVE: To study the effects of eight sesquiterpenes on dihydropiridines receptor binding and isolated vascular tension. METHODS: [3H]-Nitrendipine receptor binding assay and rabbit isolated thoracic artery tension experiment. RESULTS: Compound I, II and III significantly inhibited the binding of [3H]-nitrendipine to pig heart membranes with IC50 of 2.0×10-5 mol·L-1, 2.7×10-1 mol·L-1 and 3.9×10-1 mol·L-1, respectively. Inhibitory effects of these compounds were related to both substitutes in the central benzofuran and benzofuran itself, but the substitutes affected biological activity in more extensively than central benzofuran. Compound I and II inhibited the contraction of isolated rabbit arterial strips induced by K+ in a dose-dependent manner. CONCLUSION: These compounds are possessed of calcium antagonistic properties. The mechanism of the effect may be due to dihydropiridine calcium channel receptor.