Antioxidants as a defence against reactive oxygen species

Abstract

Reactive oxygen species are formed as a natural product of metabolic processes occurring in the organism or under the influence of external factors. Under homeostasis, they play an important role as a cellular signaling device. During oxidative stress, when they are produced in excess, they can cause damages to proteins, lipids, carbohydrates or nucleic acids. Exposure of cells and extracellular structures to free radicals activate natural mechanisms to eliminate free radicals and their derivatives. The aim of the article was to present what antioxidants are, and how they protect cells against the free radicals. The protective system against the free radicals consists of antioxidant enzymes: superoxide dismutase, catalase, glutathione peroxidases, and reductase. Lowmolecular antioxidants such as vitamin C, E, carotenoids, coenzyme Q10, flavonoids, glutathione and melatonin also play an important role.