Oxidative damage to proteins is important as it influences the function of receptors, enzymes and transport proteins. Many assaysare available to measure lipid peroxidation, such asmalonic dialdehyde (MDA) by the thiobarbituric acid (TBA) test and diene conjugation.Recently, ferrous oxidation with Xylenol Orange (FOX) assay coupled with triphenylphosphine has shown to be a reliable marker in determining levels of hydroperoxides(ROOH).Ĩ epi-prostaglandin-F2α (8-epi-PGF2α) is a marker of oxidative stress derived from oxidation of phospholipids containing arachidonic acid. ![]() Highlighting lipid peroxidation is important in many diseases it makes, for instance, a fundamental contribution to atherosclerosis. Products resulting from DNA damage by free radicals are determined in urine as 8-hydroxydeoxyguanosine (8-OHdG), which is the most widely determined compound.Apart from this, one can determine compounds such as 8-hydroxyadenine and7-methyl-8-hidroxyguanine. Spectrophotometry and chemiluminescence are example of very used methods in the detection of reactive oxygen species. Įndogenously produced reactive oxygen species are essential tolife, being involved in different biological functions, namely neurotransmission, peristalsis, platelet aggregation, blood pressure modulation, smooth muscle relaxation, immune system control, phagocytosis, the cellgrowth regulationand cellular signaling. To avoid an excess of free radicals,the cell antioxidants are trying to keep their production and consumption balance. They are very important in the molecular processes of cells, but their overproduction may lead to cell and tissue irreversible damage. It is known that free radicals are essential in tissue defense mechanisms, which are accomplished by neutrophils, macrophages and other cells,which are part of the immune system. On the other hand, ROS as well as RNS and non-radicals, like peroxynitriteanion (ONOO-), peroxynitrous acid (ONOOH), nitrosoperoxycarbonate anion (ONOOCO2-), nitronium cation (NO2+), dinitrogen trioxide (N2O3) and dinitrogentetraoxide (N2O4) are continuously generated in smallquantities during normal cellular processes. ![]() These various radical species can be generated exogenously or produced by different sources inside the cells. The most prominent members in the mentioned groups are: Superoxide Anion (O2.-), Hydroxyl Radical (HO.), Peroxyl Radical (ROO.),Hydroperoxyl radical (HO2.), Hydrogen Peroxide (H2O2), Hypochlorous Acid (HOCl), Ozone (O3), Singlet Oxygen(1O2),Nitric Oxide (NO.), Nitrogen Dioxide Radical (NO2.), Nitrous Acid (HNO2), Nitrosyl Cation (NO+), Nitrosyl Anion (NO-), Atomic Chlorine (Cl-), Hypochlorous Acid (HOCl), Chorine (Cl2), Nitronium Chloride (NO2Cl) in reactive chlorine species. The term free radical often used in biology refers to a variety of highly reactive molecules that can be divided into several categories: The best-known free radicals in the body are oxygen-based (although other atoms can also exist as free radicals) and are generated as by-products of oxidative metabolism. Some ROS are free radicalsin which an atom has one or more unpaired electrons in its outer orbital, making it particularly reactive. ROS are present in all aerobic organisms, which have evolved defense against their potentially damaging effects as well as ways to utilize them. ROS are any oxygen-containing compounds that are particularly reactive. ![]() It is well known that the exposition to certain noxious factors, such as infectious agents, pollution, UV light, radiation and cigarette smoke, may lead to the production of ROS.
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