The term "oxidative stress", entered in the last years in the biomedical everyday lexicon, indicates the set of alterations that are produced in the tissues, cells and biological macromolecules when these are exposed to an excess of oxidizing agents, both endogenous (e.g. . those produced by inflammatory cells) and exogenous (among which numerous environmental toxic substances).
In other words, we can define oxidative stress as a disorder characterized by cell damage, caused by an excess of "unstable" molecules, called free radicals, and at the cellular level produced when oxygen is used in metabolic processes to produce energy ( oxidation).
But it does not forget that oxidant is also owned by non-radical agents (eg. Hydrogen peroxide) and ionizing radiation. In our bodies there is a balance between the production and the "disposal" of free radicals, the so-called equilibrium oxide reductive or redox balance.
However, if the level of free radicals exceeds the neutralization ability of antioxidant systems, it occurs oxidative stress, in which the antioxidant defenses of the tissues are overcome by the reactivity of the free radicals.
By oxidative stress it is meant just an imbalance between the production of free radicals and the antioxidant defenses of the organism.
Free radicals cause oxidation processes at various levels:
- oxidize lipids in the cell membranes causing functional alterations of the cells;
- oxidize the low density lipoprotein (LDL), which become oxidized LDL that, in turn, damage the integrity of the vessels;
- oxidize nucleic acids (DNA and RNA), with dependent damage to the genetic material (mutations in the genetic code are often associated with the onset of cancer);
- oxidize proteins typically causing structural and functional damage to the body.
The oxidative stress reactions can accelerate cellular aging and, in recent years, has emerged in particular their relevance in a basic inflammatory diseases, chronic renal failure, diabetes, ischemia, cardiovascular diseases and certain diseases neurodegenerative.