Oxidative stress and disruption of the antioxidant defense system as triggers of diseases

Abstract

Oxidative stress is a state when the content of free radicals in a living organism is excessive. Molecules of free radical nature start a chain reaction that disrupts the integrity of cells, leading to their damage or death. The article examines the issue of intensification of oxidative stress processes and changes in the antioxidant defense system during the occurrence, development, and treatment of diseases of various etiologies. The principles of antioxidant/prooxidant balance regulation at the physiological and biochemical levels in living organisms are discussed. It was determined that the phenomenon of oxidative stress, as a completely special type of stress, is mediated by free radicals that have a destructive effect on the membranes of living cells. Free radical molecules are damaging agents for nucleic acids, proteins and lipids. The leading role in biological systems is played by oxygen free radicals, namely superoxide anion. The system of antioxidant protection, which prevents the harmful effects of oxidative stress on living organisms, is described in detail. The work describes the components of the antioxidant protection system, such as electron acceptors – vitamins E and K3; acceptors of superoxide radical anions – methionine, cysteine; scavengers of hydroxyl radicals – aliphatic alcohols; factors for detoxification of toxic products of lipid peroxidation, tocopherol, ionol, superoxide dismutase, glutathione peroxidase system, chelators of metals with variable valence (complexons) and others. According to the nature and mechanism of action, antioxidant protection agents are divided into hydrophilic and hydrophobic, enzymatic (catalase, superoxide dismutase, glutathione peroxidase system, glutathione, ascorbic acid, adrenaline, serotonin, tocopherols, retinoids, flavonoids, phospholipids, ceruloplasmin) and non-enzymatic factors. It is noted that in the human body, oxidative stress is the cause or an important component of many serious diseases, such as oncological pathologies, neurodegenerative processes (atherosclerosis and Alzheimer’s disease), diseases of the gastrointestinal tract, as well as aging. Although in some cases, oxidative stress can act as a protective mechanism in the body. Thus, the human immune system uses oxidative stress to fight pathogens, and some reactive oxygen species can serve as mediators in signal transmission during the immune response. Therefore, the biochemical mechanism of the development of many diseases of different etiology is closely related to disturbances in the antioxidant defense system and the occurrence of oxidative stress.