The FREE RADICALS are a chemical species able to have an independent existence, which contain one or more unmatched electrons and, therefore, are highly reactive towards other molecules.
The hydroxyl radical = OH and the peroxide radical ( O2O- ) are considered very damaging which, according to a theory suggested by Harman in 1954, would cause damage to cell membranes, alteration of proteins, inactivation of enzymes and production of senile pigment.
The cytotoxic action of the free radicals is counteracted by a defense system represented by enzymes that act as ANTIOXIDANTS: SOD (dismutase superoxide) that fights the action of the radicals ( O2O- ) converting them to H2O2 ( hydrogen peroxide ), CATALASE and GLUTATHIONE PEROXODASE which convert H2O2 in pure water before other complexes use it as a substrate to generate radicals = OH.
Free radicals are generated both during normal metabolic reactions that take place in the cell for both induction by external agents such as drugs, food substances, pesticides, tobacco smoke, ultraviolet radiation.
The uncontrolled photo exposure is one of the most important factors responsible for the overall process of skin aging, generating over the years epidermal atrophy, changes in pigmentation, wrinkles, dryness, and sometimes the formation of plaques.
Numerous experiments have shown that the average lifespan of human diploid cell cultures, subjected to stress, toxic substances and UV rays, is increased by the addition of antioxidant substances in the growth medium. Thus suggesting dermatologists and cosmetologists to safeguard our skin from the peril of free radicals by integrating the cosmetic products used daily for personal care with an antioxidant ingredient. In this regard, we mention the Vitamins A, C and E, which are among the most powerful agents that protect cells from lipid peroxidation.