Reactive oxygen species in health and disease

With the advent of the use of oxygen as the terminal electron acceptor in a erobic respiration, came the curse in the form of reactive oxygen species ( ROS). However, the evolving organism had developed elaborate defence machin ery to escape from these reactive byproducts of its own metabolism, and als o developed a mechanism for the utilization of these species in physiologic al processes to gain a survival advantage. ROS have been increasingly impli cated in the ageing process and in different diseases such as cancer, Alzhe imer's disease, Parkinson's disease, reperfusion injury, etc. They are also important in cellular phenomenon such as signal transduction pathways. We review the mechanisms of production of ROS in the cell, their interaction w ith cellular macromolecules, pathways of ROS-induced cell death, the mechan isms for protection from ROS-induced damage as well as the key biological a nd disease processes where ROS play an important role.