Endothelium-dependent vasodilator and antioxidant properties of a novel enzymatic extract of grape pomace from wine industrial waste

► GP extracted by enzymatic process shows antioxidant activity and polyphenol bioactive components. ► GP-EE induced endothelium- and NO-dependent in different vascular beds. ► GP-EE reduced superoxide anion produced by ET-1 stimulated vascular tissue. The aim of the present study was to evaluate the vascular effects of an enzymatic extract of grape pomace (GP-EE) on isolated arteries, focusing our attention on endothelium-derived relaxation and on its antioxidant properties. Grape pomace derived from wine making was extracted by an enzymatic process and its composition of polyphenols was evaluated by HPLC and ESI-MS/MS, detecting kaempferol, catechin, quercetin and procyanidins B1 and B2, trace levels of resveratrol and tracing out gallocatechin and anthocyanidins. GP-EE induced endothelium- and NO-dependent vasodilatation of both rat aorta and small mesenteric artery (SMA) segments and reduced Phe-induced response in aortic rings. Both ORAC and DPPH assays confirmed antioxidant scavenging properties of GP-EE, which also prevented O2·- production (assessed by DHE fluorescence) and contraction elicited by ET-1. These results provide evidence that GP-EE possesses interesting antioxidant and protective vascular properties and highlight the potential interest of this extract as a functional food.