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Numerous clinical studies have indicated that regular intake of polyphenol-rich products such as red wine and green tea is associated with a reduced risk of cardiovascular diseases.The protective effect has been attributable,in particular,to their high level of polyphenols such as flavanols and anthocyanins.The beneficial effect of polyphenols on the vascular system involves their ability to improve the lipid profile and to prevent platelet activation and inflammatory responses,and possibly also by a direct action at blood vessels.Indeed,grape-derived polyphenols and tea catechins are potent inducers of endothelium-dependent relaxations of isolated blood vessels by causing a sustained stimulation of the endothelial formation of nitric oxide(NO)and endothelium-derived hyperpolarization,two potent vasoprotective mechanisms.Besides grape-derived and tea products,several red and black fruit-derived products induce also potent vasoprotective effects.Intake of polyphenol-rich products has been shown to retard the induction of aging-related endothelial dysfunction and to improve an established aging-related endothelial dysfunction in rats.The beneficial effect is mostly due to the normalization of the high level of oxidative stress in the arterial wall and of the local angiotensin system.Moreover,polyphenol-rich products prevented the induction of replicative senescence at indicated by levels of senescence-associated beta-galactosidase activity and of key cell cycle regulators p53/p21 and p16 in cultured endothelial cells.The induction of endothelial senescence is associated with the down-regulation of endothelial NO synthase expression and the up-regulation of tissue factor expression most likely triggered by NADPH oxidase-and cyclooxygenase-derived oxidative stress,and leads to a reduced ability of endothelial cells to effectively inhibit platelet aggregation.Thus,regular intake of polyphenol-rich products can delay the induction of aging-related endothelial dysfunction most likely by preventing endothelial senescence,and as a consequence help to maintain an optimal protective effect of endothelial cells on the vascular system.
Numerous clinical studies have indicated that regular intake of polyphenol-rich products such as red wine and green tea is associated with reduced disease of cardiovascular diseases. The protective effect has been attributable to, in particular, to their high level of polyphenols such as flavanols and anthocyanins. The beneficial effect of polyphenols on the vascular system involves their ability to improve the lipid profile and to prevent platelet activation and inflammatory responses, and possibly also by a direct action at blood vessels. Dede, grape-derived polyphenols and tea catechins are potent inducers of endothelium-dependent relaxations of isolated blood vessels by causing a sustained stimulation of the endothelial formation of nitric oxide (NO) and endothelium-derived hyperpolarization, two potent vasoprotective mechanisms. Besides grape-derived and tea products, several red and black fruit- derived products induce also potent vasoprotective effects. Intake of polyphenol-rich products has be en shown to retard the induction of aging-related endothelial dysfunction and to improve an established aging-related endothelial dysfunction in rats. The beneficial effect is mostly due to the normalization of the high level of oxidative stress in the arterial wall and of the local angiotensin system. Moreover, polyphenol-rich products prevented the induction of replicative senescence at indicated by levels of senescence-associated beta-galactosidase activity and of key cell cycle regulators p53 / p21 and p16 in cultured endothelial cells. The induction of endothelial senescence is associated with the down-regulation of endothelial NO synthase expression and the up-regulation of tissue factor expression most likely triggered by NADPH oxidase-and cyclooxygenase-derived oxidative stress, and leads to reduced ability of endothelial cells to effectively inhibit platelet aggregation. intake of polyphenol-rich products can delay the induction of aging-related endothelial dysfunctionmost likely by preventing endothelial senescence, and as a consequence help to maintain an optimal protective effect of endothelial cells on the vascular system.