Overview:The Role Of Reactive Oxygen Species In Pathogenesis Of Neurodegenerative Disease

Reactive oxygen species (ROS) are a group of compounds derived from the incomplete reduction of molecular oxygen. They are highly reactive molecules that consist of a number of diverse chemical species including superoxide anion(O2 .− ), hydroxyl radical (-OH), and hydrogen peroxide (H2O2). Primary physiological source of ROS is cellular respiration. During respiration, electrons are passed through four protein complexes (Complex I, II, III, and IV) which reside in the mitochondrial inner membrane. At normal physiological condition, ROS play an important role in cell proliferation; differentiation; apoptosis and some other metabolize activities. However, a small percentage of electrons can escape the electron transport chain prematurely, leading to incomplete reduction of molecular oxygen and formation of the superoxide anion O 2[1]. But excessive ROS can induce the injury to the cell which leads to many diseases. As ROS are generated mainly as by-products of mitochondrial respiration, mitochondria are thought to be the primary target of oxidative damage and play an important role in aging. Especially their potential to cause oxidative deterioration of DNA, protein, and lipid, ROS has been implicated as one of the causative factors of aging [1]. Emerging evidence has linked mitochondrial dysfunction to a variety of age-related diseases, including neurodegenerative diseases and cancer. Details of the precise relationship between ROS-induced damage, mitochondrial dysfunction, and aging remain to be elucidated.