Oxidative Stress
Introduction
Reactive oxygen species (ROS) are continuously formed in biological systems. ROS comes in common forms such as Superoxide (O2•−), Hydrogen Peroxide (H2O2), and perhaps the most deleterious, the Hydroxyl Radical (OH•). These free radicals wreak havoc on the cell and lead to protein dysfunction, DNA damage, and lipid peroxidation, resulting in apoptosis. Any increase in radical production or decrease in the defense against ROS induces oxidative stress. This imbalance between ROS formation and ROS detoxification is believed to be involved in a variety of pathogenic processes, such as ischemia-reperfusion (I/R) injury. During the reperfusion phase following ischemia, production of ROS increases remarkably, leading to the breakdown of antioxidant systems and generates rapid and severe damage. The Hydroxyl Radical in particular is poised to be formed in vivo from ferrous iron and hydrogen peroxide via the Fenton reaction (2). In order to analyze the Hydroxyl Radical using Electron Spin Resonance (ESR), a spin trap must be utilized so that to produce a relatively long lived and observable free radical product called the spin adduct.
References
LLoyd, Roger; Hanna, Phillip; Mason, Ronald, The origin of the hydroxyl radical oxygen in the fenton reaction, Free Radical Biology and Medicine, 22, 5, pp 885-888.