When there is an imbalance between antioxidant and pro-oxidants such as reactive oxygen species (ROS) the oxidative stress takes place. In ROS superoxide anion (O2•-) is the most abundant, it is considered as a byproduct of electron transport chain, this radical has short lifetime of 10-5s, and is formed by one-electron reduction of molecular oxygen. O2•- is not particularly reactive, however it is responsible for the formation of other types of radical such as hydroxyl (•OH) and hydroperoxyl (•HO2) and non-radical species as hydrogen peroxide (H2O2). Also, O2•- can react with nitric oxide (NO) to form peroxynitrite (ONOO-) and hydrogen peroxide to obtain the hydroxyl radical (-OH), so the superoxide anion is considered the primary radical. O2•- tends to oxidize important biological macromolecules such as nucleic acids, lipids and proteins, but also acts as a reducing agent by donating an electron to metals like iron (Fe+2) or copper (Cu+2) during Fenton's reaction. In food products, superoxide O2•- can be generated when these are subjected during processing to treatments such as pulsed gamma electric field, irradiation, ohmic and microwave, but the main source of superoxide formation in foods are oxidative reactions. Lipid oxidation in foods causes quality deterioration, formation of unhealthy compounds, and negatively affects sensory properties in fruits, vegetables, meat and dairy products, reducing their shelf life and causing food spoilage. In the human body, formation of O2•- is inevitable, because it is generated in the mitochondria during the respiration process, but it is also implicated in cancer, rheumatoid arthritis, cardiovascular diseases (atherosclerosis, arterial hypertension and heart failure) and neurodegenerative diseases (Alzheimer, Parkinson and epilepsy). The main objective of this review is to collect information related to the mechanism of action of the superoxide anion both as a generator of spoilage in food products and its action in the human body by helping to the development of some diseases.
Key words: oxidative stress, superoxide anion, food spoilage, degenerative diseases.