Stress oxydant et antioxydants ?

All aerobic organisms are fully dependent upon mitochondrial oxidative phosphorylation for adenosine triphosphate (ATP) supply and energy homeostasis. Oxygen supply is therefore mandatory for survival because of very high oxidative potential, but it is concurrently one of the most harmful compounds by oxidizing every biological molecule. Hence, living organisms have developed powerful antioxidant systems as well as sensitive signalling systems. Antioxidant pathways are based on both enzymatic (SOD, catalase, glutathione peroxidase, etc.) and non-enzymatic (vitamin C, vitamin E, polyphenols, etc.) elements. The oxidative stress-related signalling system is based on hydrogen peroxide, which is produced by a family of enzymes: the superoxide dismutases. Oxidative stress is involved in several acute or chronic diseases but antioxidant therapies have not been proven very successful so far. Recent data indicate that a moderate degree of oxidative stress could be protective in increasing the activity of antioxidant pathway.