INTRODUCTION AND SCOPE OF REVIEW been shown to cause damage to DNA, RNA, protein, and lipids. Active oxygen species are produced as an ines-Oxidative stress can be functionally defined as an excess capable by-product of normal aerobic metabolism, and their of prooxidants in the cell. Active oxygen molecules have production is further enhanced by exposure to certain environments or by dietary or disease conditions. Oxygen toxicity results wh~en the-degree of oxidative stress exceeds the * Corresponding author. capacity of the cell defense systems. Oxidative stress is 561