0000000000595619
AUTHOR
M. D. Ivorra
Vascular Activity of (-)-Anonaine, (-)-Roemerine and (-)-Pukateine, Three Natural 6a(R)-1,2-Methylenedioxyaporphines with Different Affinities for α1-Adrenoceptor Subtypes
We have studied the mechanism of action of three 6a( R)-1,2-methylenedioxyaporphines as vasorelaxant compounds. The alkaloids assayed showed different affinities for the three human cloned alpha (1)-adrenoceptor (AR) subtypes stably expressed in rat-1 fibroblasts, showing lower affinity for alpha(1B)-AR with regard to the alpha(1A)- or alpha(1D)-subtypes. These three natural compounds are more potent inhibitors of [ (3)H]-prazosin binding than of [ (3)H]-diltiazem binding to rat cerebral cortical membranes. As all these alkaloids inhibited noradrenaline (NA)-induced [ (3)H]-inositol phosphate formation in cerebral cortex and rat tail artery, they may be safely viewed as alpha (1)-AR antagon…
Effect of tormentic acid on insulin secretion in isolated rat islets of langerhans
Tonnentic acid was isolated as the hypoglycemic agent of Poterium ancistroides Desf. The present study reports effects of this compound on isolated islets of Langerhans. We demonstrate that tormentic acid in the presence of 1.66 mM glucose initiates insulin secretion by isolated rat islets of Langerhans in a dose-dependent fashion at concentrations ranging from 0.05 to 0.5 mM. However, the compound has no effect on the insulin-releasing capacity of 16.6 mM glucose. Similar results were obtained with the sulfonylurea glibenclamide (0.01 mM) used as a reference. These results suggest that the hypoglycemic effect of tormentic acid is due to a diect effect of the compound in vitro.