Reactive oxygen species (ROS) are generated as a result of the reduction of oxygen during aerobic respiration and by various enzymatic systems within the cell. At physiological levels, ROS contribute to cell signaling and host defense. Increased ROS generation, above the detoxification capacity of the biological system, results in oxidative stress and cellular damage. The main damage to cells results from the ROS-induced alteration of macromolecules such as polyunsaturated fatty acids in membrane lipids, essential proteins, and DNA. ROS has been implicated in disease states, such as Alzheimer′s disease, Parkinson′s disease, cancer, and aging.
