Oxidative stress reflects an imbalance between the systemic manifestation of
reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal
redox state of cells can cause toxic effects through the production of
peroxides and
free radicals that damage all components of the cell, including
proteins,
lipids, and
DNA. Oxidative stress from oxidative metabolism causes base damage, as well as strand breaks in DNA. Base damage is mostly indirect and caused by reactive oxygen species (ROS) generated, e.g. O
2- (superoxide radical), OH (hydroxyl radical) and H
2O
2 (hydrogen peroxide). Further, some reactive oxidative species act as cellular messengers in
redox signaling. Thus, oxidative stress can cause disruptions in normal mechanisms of
cellular signaling.