ABSTRACT
Over the past few decades, free radicals, highly reactive and thereby destructive molecules, have become known increasingly for their importance to human health and disease. Many common and life threatening human diseases, including atherosclerosis, diabetes, cancer and aging, have free radical reactions as an underlying mechanism of injury. Because our bodies are continuously exposed to free radicals and other reactive species of oxygen (ROS) from both external sources (sunlight, other forms of radiation, pollution) and generated endogenously, ROS-mediated tissue injury is a nal common pathway for a number of disease processes. Radicals of oxygen (superoxide anion, hydroxyl radicals and peroxy radicals), reactive non-radical oxygen species such as hydrogen peroxide and singlet oxygen, as well as carbon, nitrogen and sulfur radicals make up the variety of reactive molecules that can cause damage to cells. Our conceptual understanding of the interaction of such ROS with living organisms has undergone a remarkable evolution.
