There is evidence that oxidative stress, defined as a persistent imbalance between the production of highly oxidative compounds and antioxidant defenses, leads to tissue damage. Oxygen metabolism generates free radicals and/or non-radical reactive oxygen species. The mitochondria, through the electron transport chain, are the main generator of these species. The antioxidant defense system has the function of inhibiting and/or reducing the damage caused by the deleterious free radicals and/or non-radical reactive oxygen species. This system is divided into enzymatic (superoxide dismutase, catalase and glutathione peroxidase), and nonenzymatic. The nonenzymatic system consists of a variety of antioxidant substances, which may be endogenous or dietary. This study proposed to review the main mechanisms of reactive oxygen species generation and the role of the most relevant agents of the antioxidant defense system on the biomarkers of oxidative stress. The main exogenous factors that modulate oxidative stress will also be discussed.
Oxidative stress; Free radicals; Reactive oxygen species; Antioxidants; Reactive nitrogen species
