Vascular endothelium dysfunction is the basic cause of development of cardiovascular disorders and is characterised by bioactive NO deficiency. Oxidative stress induced by the generally known atherosclerosis risk factors such as smoking, hypercholesterolaemia, hypertension, diabetes etc. was found to contribute to low bioavailability of NO.

The present investigations indicate that polyphenols may exert a protective effect on vascular endothelium not only through scavenging oxygen free radicals but also through their direct effect on the system of NADPH oxidases, xanthine oxidases and myeloperoxidase. The mechanism of this process is a direct action of polyphenols on the cellular NF-KB transcription factor. Polyphenols, and in particular catechins and anthocyanes, may also contribute in this mechanism to the inhibition of cyclooxygenase-2 (COX-2) activity.

It is suggested that polyphenols may actively counteract apoptosis of endothelial cells through activation of the signalling pathway with participation of Src-ERK1/2 and inhibition of bax protein expression and caspase-3 inhibition.

Polyphenols are also able to activate eNOS, contributing to an increase in the intracellular level of Ca++ and activation of phosphatidylinositol kinase (PI 3-K), which in turn leads to eNOS phosphorylation.

Recently it has been shown that polyphenols may inhibit the activity of metalloproteinase and prevent in this way atherosclerotic plaque rupture, the consequences of which are acute coronary events.

An important element of endothelial protection is inhibition of platelet adhesion and aggregation.

Polyphenols inhibiting phospholipase C activity may exert an indirect effect on release of arachidonic acid which is the substrate for the synthesis of pro-aggregative thromboxane. Indeed, as it was proven in in vivo studies in animals and humans, resveratrol, a polyphenol originating from grapes, is a potent inhibitor of platelet aggregation caused by thrombin and cathepsin S.

As we found in our clinical studies, polyphenols isolated from chokeberry fruit not only significantly lower systolic and diastolic blood pressure but also reduce inflammation associated with ischaemic heart disease.

In summary, the biological effects of pleiotropic actions of polyphenols indicate their usefulness in atherosclerosis prevention.

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