BODY'S ANTIOXIDANT SYSTEM

The antioxidant system of the body is a branched, multicomponent network of physiologically active compounds that control the entire chain of oxygen and organic radicals formed during oxidation-reduction processes at a steady state level.

The high intensity and diversity of oxidation-reduction processes in a living organism determine the diversity of components of the antioxidant protection system, combining enzyme, protein and vitamin compounds.

Among the existing classifications, of particular interest, in our opinion, is the classification of endogenous antioxidants, which is based on the definition of their role and place of action in the chain of antiradical processes.
According to this classification, endogenous antioxidants are divided into 4 groups: primary, secondary, tertiary and quaternary.

The antioxidant link of the detoxification system, participating in the inactivation of free radical, oxygen and peroxide compounds, implementing general regulation of various oxidative processes occurring in a living organism, ensures the maintenance of the intensity of oxidative processes at a stationary level. These factors allow us to consider the antioxidant link of the detoxification system as a system that takes direct part in the implementation of the mechanisms of non-specific resistance of the organism.

Thus, the antioxidant system of the body is an integral system, the individual components of which ensure the regulation of oxidation-reduction processes in the body, sequential or independent inactivation of the entire variety of free-radical compounds, as well as the restoration of disorders caused by free-radical oxidation. The total amount of bioantioxidants in the body creates a "buffer antioxidant system" with a certain capacity, and the ratio of prooxidant and antioxidant processes in the body determines the antioxidant status of the body. Under conditions of normal functioning of the body, the antioxidant system ensures a balanced course of oxidative and antioxidant processes.

Importance of oxidative stress

According to modern concepts, oxidative stress is an important pathogenetic factor in the development of many different nosological forms of diseases: oncological, cardiovascular (atherosclerosis, ischemia and reperfusion); musculoskeletal system (rheumatoid arthritis); abdominal organs (Crohn's disease, liver cirrhosis, diabetes); respiratory tract; central nervous system (schizophrenia, manic-depressive psychosis, Down syndrome); eye diseases (cataracts), etc.

Failure of the antioxidant defense system

Failure of the antioxidant defense system leads to an increase in oxidative processes in the body. Excess free radicals and peroxide compounds initiate the oxidation of various biological substrates (proteins, lipids, nucleic acids, etc.), causing structural and biochemical disturbances in cells: changes in membrane permeability, intercellular contacts, blocking of biosynthesis processes, damage to the genetic apparatus of cells.

Antioxidant studies

In the last decade, specialists in many areas of biochemistry, biophysics, physiology, and immunology have shown an active interest in studying the oxidative-antioxidant status of the body in a wide range of people. Methods are being developed to assess the balance of oxidative-antioxidant processes, as well as the level and activity of individual components of the antioxidant defense system.

As a result of these studies, it was found that inhibition of the functional activity of components of the antioxidant defense system is a characteristic sign of biochemical disorders that occur in various diseases.

The study of antioxidant status can be considered as one of the ways to assess the system of nonspecific resistance of the body, which in turn can contribute to the development of effective preventive and therapeutic measures for various pathological conditions accompanied by a violation of the oxidative-antioxidant balance.

Particular attention of researchers is drawn to those components of endogenous antioxidant protection that are already used at present or can be used in the future as promising means for correcting disorders of the functional activity of the body's antioxidant protection. In this regard, the primary antioxidants ceruloplasmin and lactoferrin are of particular interest.

Antioxidant defense system in patients with malignant neoplasms

By now it has been proven that one of the initiating mechanisms of carcinogenesis is long-term exposure to chemical or physical factors, as a result of which the processes of radical formation in the body are enhanced. Organic and oxygen radicals, interacting with nucleic acids, damage the genetic material of cells, activate the processes of lipid peroxidation of cell membranes, which leads to disruption of the structural homeostasis of cells, inactivation of membrane-bound enzyme systems.

As a result, the balanced course of biochemical processes of cell activity is disrupted, which in turn contributes to neoplastic transformation. Thus, already in the pathogenesis of the occurrence of malignant neoplasms, mechanisms of activation of oxidative processes are embedded, accompanied, as a rule, by inhibition of antioxidant protection.

Excessive radical formation contributes not only to the initiation but also to the progression of the tumor process since biochemical and structural changes occurring in cells lead to serious metabolic disorders in the body: protein synthesis processes are reduced, the activity of proteinase inhibitors and complement changes, the process of fibrinolysis-blood coagulation is disrupted, intercellular contacts, the activity of hematopoietic and immunocompetent cells change, etc.

Violation of the relationship between the most important biochemical reactions, intensification of oxidative processes contributes to the accumulation of toxic products in the body, which leads to the suppression of the mechanisms of natural resistance of the body, causing the occurrence of cancer endotoxicosis and contributes to the progression of the tumor process. Activated oxygen metabolites can be considered as a tool for tumor transformation, causing spontaneous and induced by physical and chemical factors carcinogenesis.

Effects of excessive radical formation

Cancer endotoxicosis

Oxidation and tumors

Oxidative process and tumor aggression

Numerous studies indicate that the development of malignant neoplasms is accompanied by an increase in the intensity of oxidative processes in the body, which is manifested in an increase in the content of lipid peroxidation products in the blood serum.

Thus, a significant increase in the concentration of malonic dialdehyde, the final product of lipid peroxidation, in the blood serum is noted in patients with cancer of the gastrointestinal tract, liver, pancreas, respiratory tract (lungs, bronchi), gynecological neoplasms.

At the same time, a number of authors note an increase in lipid peroxidation as the prevalence of the tumor process increases, i.e. an increase in the phenomena of cancer toxicosis caused by tumor aggression.

Increase in oxidative processes

Increased oxidative processes in patients with malignant tumors are accompanied by disturbances in the functional activity of the antioxidant defense system, leading to suppression of the overall antioxidant activity, which is due to depletion of both the content and activity of various components of the antioxidant defense system - both primary antioxidants (metalloproteins, enzymes) and secondary antioxidants - vitamins.

It is noted, in particular, that a decrease in ceruloplasmin in plasma, described in humans and animals, was associated with an increase in the incidence of tumor development.

Thus, the development of a malignant neoplasm is accompanied by significant disturbances in the antioxidant defense system, which indicates the failure of detoxification processes and is one of the manifestations of cancer toxicosis.