Résumé
This chapter discusses various methodological and approaches for studying the mechanisms by which plant polyphenols mediate their vascular effect. The functional and biochemical determinations of the effect of polyphenols on vascular tissues and the cellular mechanism by which polyphenols might produce NO are also discussed. Epidemiological studies have shown that the low incidence of coronary heart disease in the French and other Mediterranean populations, despite a diet rich in saturated fat, can be attributed to the high rate of polyphenol consumption derived from wine, tea, or various plant foods. Among the plant polyphenols, mostly flavonoids are the active compounds responsible for protective effects against cardiovascular diseases. For a long time, the sole accepted mechanism by which flavonoids mediated their effects was their antioxidant and free radical scavenging properties. These properties may explain why these compounds were able to decrease serum low density lipoproteins and platelet aggregation. However, it has been reported that another therapeutically relevant effect of polyphenols on the cardiovascular system may be because of their ability to interact with the pathway leading to the generation of nitric oxide (NO) from the vascular endothelium. This pharmacological effect of polyphenols is of importance because NO has been shown to have vasorelaxant and antiaggregatory properties.