Reactive oxygen species (ROS) are a family of molecules including molecular oxygen and its derivatives produced in all aerobic cells. Extensive production of ROS has been implicated in the oxidation of biological macromolecules, such as DNA, proteins, carbohydrates, and lipids. This condition has commonly been referred to as oxidant stress. Oxidant stress is involved in the pathogenesis of many cardiovascular diseases and is closely related to vascular endothelial dysfunction (1 ). Endothelial dysfunction includes altered anticoagulant and antiinflammatory properties of the endothelium, impaired modulation of vascular growth, and dysregulation of vascular remodeling (2 ).
