Reactive oxygen species (ROS) are produced by living organisms as a result of normal cellular metabolism and environmental factors (UV rays, air pollutants or cigarette smoke, for example).
Although highly reactive molecules, a tightly regulated production of ROS is beneficial for normal physiological functions. They are indeed involved in signalling reactions and the immune response.
Excessive ROS, however, may have detrimental effects. Caused by ROS overproduction and/or a decrease in antioxidant defences, the imbalance between ROS production and detoxification is termed “oxidative stress”.
Largely encouraged by our modern lifestyle habits, this oxidative stress results in protein, lipid and DNA damage, disruptions of the normal signal transduction pathway and has been implicated in numerous human disorders.