Endothelial dysfunction represents an imbalance between vasodilatory and vasoconstrictory molecules secreted
by endothelium. Oxidative stress is a major factor leading to endothelial dysfunction with significant prognostic implications
for cardiovascular events. The generation of reactive oxygen species is strongly related to various oxidase enzymes
such as xanthine oxidase, uncoupled endothelial nitric oxide synthase, cyclooxygenase, glucose oxidase, lipooxygenase,
nicotinamide-adenine dinucleotide phosphate oxidase and to mitochondrial electron transport mechanisms. Several pharmaceutical
agents exert effects beyond their principal role, such as anti-inflammatory and antioxidant, while the reports on
antioxidant vitamins remain controversial especially those based on large scale studies. Moreover, there are studies on
other agents already patented, but these are not well evaluated. Recently, there is growing interest in the role of dietary
flavonoids and their potential to improve endothelial function by modifying oxidative stress status. Flavonoids are
important components of 'functional foods', with beneficial effects on cardiovascular health, mainly due to their antioxidant
activity. However, the vascular-protective role of flavonoids and especially their antioxidant properties are still under
Endothelial dysfunction, nitric oxide, antioxidants, flavonoids.
Athens University Medical School, Hippokration Hospital, Vasilisis Sofias 114, 115 28, Athens, Greece.