Furthermore, there are indications that resveratrol can reduce the risk of stroke by interfering with molecular mechanisms in blood vessels. This is done, firstly by reducing the sensitivity of the blood vessels to damage through reduced activity of angiotensin (systemic hormone causes contraction of the blood vessels which can increase blood pressure), and secondly, by increased production of the vasodilator nitric oxide substance (a beneficial compound which causes relaxation of blood vessels).
All grapes, and especially those derived from red / purple grapes, contain anthocyanins, another class of polyphenolic antioxidants. It has been found that anthocyanins have anti-allergic, anti-inflammatory, anti-microbial and anticancer action