Oxigen and oxidation I: Reactive oxigen species and oxidative damage to biological substrates | Oxígeno y oxidación I: Especies reactivas de oxígeno y daño oxidativo de sustratos biológicos

Abstract

Human beings and eucariotic organisms need oxygen for efficient energy production by using electron transport chains with molecular oxygen as the terminal electron acceptor. Thus, oxygen is essential for human life. However, during the use of oxygen several reactive oxygen species are generated, leading to damaging effects on biological substrates. This is call the aerobic paradox. The production of reactive oxygen species and natural antioxidant defense are approximately balanced, but it is easy to tip this balance in favour of the reactive oxygen species and create the situation of oxidative stress. Oxidative stress can result from depletion of dietary antioxidants due to malnutrition or by excess production of reactive oxygen species in different situations, such as exposure to pollution or radiation, heavy sport or chronic inflammatory diseases. In this review the reactivity and physiological generation of the different reactive oxygen species is described (superoxide radical, hydrogen peroxide, oxygen molecular in triplet state, and hydroxyl radical). In addition the mechanism through biological substrates (lipids, proteins and nucleic acids) are oxidised is described.