Vasodilator Effects of Quercetin 3-O-Malonylglucoside Are Mediated by the Activation of Endothelial Nitric Oxide Synthase and the Opening of Large-Conductance Calcium-Activated K Channels in the Resistance Vessels of Hypertensive Rats.

We used molecular docking as a computational tool to predict the binding affinities and interactions of quercetin 3-O-malonylglucoside (Q3MG) with vascular target proteins. First, the proteins 1M9M (human endothelial nitric oxide synthase; eNOS) and 6ND0 (human large-conductance voltage- and calcium-activated K channels; BK) were downloaded from the Protein Data Bank and submitted to molecular docking studies, revealing Q3MG binding affinities for both proteins. The vascular effect of Q3MG was investigated in the perfused mesenteric vascular beds (MVBs) of spontaneously hypertensive rats. In preparations with functional endothelium, Q3MG dose-dependently reduced the perfusion pressure in MVBs. Removal of the endothelium or inhibition of the nitric oxide synthase enzyme by L-NAME blocked the vasodilation induced by Q3MG. Perfusion with a physiological solution containing high KCl or the use of a non-selective blocker of K channels, as well as perfusion with iberiotoxin, completely abolished the vasodilatory effects of Q3MG. The data obtained suggest that the vascular effects of Q3MG involve the activation of the NO/cGMP pathway followed by the opening of BK.