Antioxidants: effects on the body and sources

Antioxidants fight free radicals – molecules whose structure is unstable and whose impact on the body is harmful. Free radicals can cause aging processes and damage the body’s cells. Because of this, they need to be neutralized. Antioxidants cope with this task perfectly.

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What are free radicals?

Free radicals are the result of incorrect processes that occur inside the body and the result of human activity. Free radicals also appear from an unfavorable external environment, in a bad climate, harmful production conditions and temperature fluctuations.

Even if a person leads a healthy lifestyle, he or she is exposed to free radicals, which destroy the structure of the body's cells and activate the production of further portions of free radicals. Antioxidants protect cells from damage and oxidation as a result of exposure to free radicals. But in order for the body to remain healthy, sufficient portions of antioxidants are needed. Namely, products containing them and supplements with antioxidants.

Effects of Free Radicals

Every year, medical scientists add to the list of diseases caused by the effects of free radicals. This includes the risk of cancer, heart and vascular diseases, eye diseases, in particular cataracts, as well as arthritis and other bone tissue deformations.

Antioxidants successfully fight these diseases. They help make a person healthier and less susceptible to environmental influences. In addition, studies prove that antioxidants help control weight and stabilize metabolism. That is why a person should consume them in sufficient quantities.

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Antioxidant beta-carotene

There is a lot of it in orange vegetables. These are pumpkin, carrots, potatoes. And there is also a lot of beta-carotene in green vegetables and fruits: different types of lettuce (leafy), spinach, cabbage, especially broccoli, mango, melon, apricots, parsley, dill.

Beta-carotene dosage per day: 10,000-25,000 units

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Antioxidant vitamin C

It is good for those who want to strengthen their immunity, reduce the risk of gallstones and kidney stones. Vitamin C is quickly destroyed during processing, so vegetables and fruits with it should be eaten fresh. There is a lot of vitamin C in rowan berries, black currants, oranges, lemons, strawberries, pears, potatoes, bell peppers, spinach, tomatoes.

Daily dose of vitamin C: 1000-2000 mg

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Antioxidant vitamin E

Vitamin E is essential in the fight against free radicals when a person has increased sensitivity to glucose and its concentration in the body is too high. Vitamin E helps to reduce it, as well as insulin resistance. Vitamin E, or tocopherol, is naturally found in almonds, peanuts, walnuts, hazelnuts, as well as asparagus, peas, wheat grains (especially sprouted), oats, corn, cabbage. It is also found in vegetable oils.

It is important to use natural, not synthetic, vitamin E. It can be easily distinguished from other types of antioxidants by the label with the letter d. That is, d-alpha-tocopherol. Unnatural antioxidants are designated as dl. That is, dl-tocopherol. Knowing this, you can benefit your body, not harm it.

Daily dose of vitamin E: 400-800 units (natural form d-alpha-tocopherol)

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Antioxidant selenium

The quality of selenium that enters your body depends on the quality of the products grown with this antioxidant, as well as the soil in which they were grown. If the soil is poor in minerals, then the selenium in the products grown in it will be of low quality. Selenium can be found in fish, poultry, wheat, tomatoes, broccoli,

The selenium content in plant products depends on the condition of the soil in which they were grown, on the content of minerals in it. It can be found in broccoli, onions.

Selenium dosage per day: 100-200 mcg

What antioxidants can help you lose weight effectively?

There are types of antioxidants that activate the metabolism process and help you lose weight. They can be bought at the pharmacy and consumed under the supervision of a doctor.

Antioxidant coenzyme Q10

The composition of this antioxidant is almost the same as that of vitamins. It actively promotes metabolic processes in the body, in particular, oxidative and energetic. The longer we live, the less our body produces and accumulates coenzyme Q10.

Its properties for immunity are priceless - they are even higher than those of vitamin E. Coenzyme Q10 can even help cope with pain. It stabilizes blood pressure, in particular, with hypertension, and also promotes good functioning of the heart and blood vessels. Coenzyme Q 10 can reduce the risk of heart failure.

This antioxidant can be obtained from the meat of sardines, salmon, mackerel, perch, and it is also found in peanuts and spinach.

In order for the antioxidant Q10 to be well absorbed by the body, it is advisable to take it with oil - it dissolves well there and is quickly absorbed. If you take the antioxidant Q10 in tablets orally, you need to carefully study its composition so as not to fall into the trap of low-quality products. It is better to buy such drugs that are placed under the tongue - this way they are absorbed by the body faster. And it is even better to replenish the body's reserves with natural coenzyme Q10 - the body absorbs and processes it much better.

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Action of essential fatty acids

Essential fatty acids are essential for our body because they play many roles in it. For example, they help produce hormones, as well as hormone transmitters – prostaglandins. Essential fatty acids are also necessary for the production of hormones such as testosterone, corticosteroids, in particular cortisol, and progesterone.

Essential fatty acids are also needed for normal brain activity and nerves. They help cells protect themselves from damage and recover from it. Fatty acids help synthesize other products of the body's vital activity - fats.

Fatty acids are a deficiency unless a person consumes them with food. Because the human body cannot produce them itself.

Omega-3 fatty acids

These acids are especially good when it comes to fighting excess weight. They stabilize metabolic processes in the body and promote more stable functioning of internal organs.

Eicosapentaenoic acid (EPA) and alpha-linolenic acid (ALA) are representatives of Omega-3 fatty acids. It is best to take them from natural products, not from synthetic additives. These are deep-sea fish mackerel, salmon, sardines, plant oils - olive, corn, nut, sunflower - they have the highest concentration of fatty acids.

But even despite the natural appearance, you cannot consume a lot of such supplements, since they can increase the risk of developing muscle and joint pain due to the increased concentration of eicosanoid substances.

Ratio of substances in fatty acids

Also make sure that the supplements do not contain substances that have been thermally processed - such additives destroy the useful substances of the drug. It is more beneficial for health to use those supplements that contain substances that have undergone a process of purification from decomposers (catamines).

It is better to take those acids that you consume from natural products. They are better absorbed by the body, there are no side effects after their use and there is much more benefit for metabolic processes. Natural supplements do not contribute to weight gain.

The ratio of useful substances in fatty acids is very important to avoid malfunctions in the body. Especially important for those who do not want to gain weight is the balance of eicosanoids - substances that can have both a bad and a good effect on the body.

As a rule, for the best effect, you need to consume omega-3 and omega-6 fatty acids. This will give the best effect if the ratio of these acids is 1-10 mg for omega-3 and 50 - 500 mg of omega-6.

Omega-6 fatty acids

Its representatives are LA (linoleic acid) and GLA (gamma-linolenic acid). These acids help build and restore cell membranes, promote the synthesis of unsaturated fatty acids, help restore cellular energy, control mediators that transmit pain impulses, and help strengthen the immune system.

Omega-6 fatty acids are found in abundance in nuts, beans, seeds, vegetable oils, and sesame seeds.

Structure and mechanisms of action of antioxidants

There are three types of pharmacological preparations of antioxidants - inhibitors of free radical oxidation, differing in their mechanism of action.

• Oxidation inhibitors that interact directly with free radicals;
• Inhibitors that interact with hydroperoxides and “destroy” them (a similar mechanism was developed using the example of RSR dialkyl sulfides);
• Substances that block free-radical oxidation catalysts, primarily ions of variable-valence metals (as well as EDTA, citric acid, cyanide compounds), by forming complexes with metals.

In addition to these three main types, we can distinguish the so-called structural antioxidants, the antioxidant effect of which is due to changes in the structure of membranes (androgens, glucocorticoids, and progesterone can be classified as such antioxidants). Antioxidants, apparently, should also include substances that increase the activity or content of antioxidant enzymes - superoxide dismutase, catalase, glutathione peroxidase (in particular, silymarin). Speaking of antioxidants, it is necessary to mention another class of substances that enhance the effectiveness of antioxidants; being synergists of the process, these substances, acting as proton donors for phenolic antioxidants, contribute to their restoration.

The effect of a combination of antioxidants with synergists significantly exceeds the effect of a single antioxidant. Such synergists, which significantly enhance the inhibitory properties of antioxidants, include, for example, ascorbic and citric acids, as well as a number of other substances. When two antioxidants interact, one of which is strong and the other weak, the latter also acts primarily as a protodonator in accordance with the reaction.

Based on the reaction rates, any peroxidation inhibitor can be characterized by two parameters: antioxidant activity and antiradical activity. The latter is determined by the rate at which the inhibitor reacts with free radicals, and the former characterizes the total ability of the inhibitor to inhibit lipid peroxidation, it is determined by the ratio of reaction rates. These indicators are the main ones in characterizing the mechanism of action and activity of a particular antioxidant, but these parameters have not been studied sufficiently for all cases.

The question of the relationship between the antioxidant properties of a substance and its structure remains open. Perhaps this question has been most fully developed for flavonoids, the antioxidant effect of which is due to their ability to quench OH and O2 radicals. Thus, in a model system, the activity of flavonoids in terms of "eliminating" hydroxyl radicals increases with an increase in the number of hydroxyl groups in the B ring, and the hydroxyl at C3 and the carbonyl group at position C4 also play a role in increasing the activity. Glycosylation does not change the ability of flavonoids to quench hydroxyl radicals. At the same time, according to other authors, myricetin, on the contrary, increases the rate of formation of lipid peroxides, while kaempferol reduces it, and the effect of morin depends on its concentration, and of the three substances named, kaempferol is the most effective in terms of preventing the toxic effects of peroxidation. Thus, even with regard to flavonoids, there is no final clarity on this issue.

Using ascorbic acid derivatives with alkyl substituents in position 2-O as an example, it has been shown that the presence of a 2-phenolic oxy group and a long alkyl chain in position 2-O in the molecule is of great importance for the biochemical and pharmacological activity of these substances. The significant role of the presence of a long chain has also been noted for other antioxidants. Synthetic phenolic antioxidants with a shielded hydroxyl and short-chain tocopherol derivatives have a damaging effect on the mitochondrial membrane, causing uncoupling of oxidative phosphorylation, while tocopherol itself and its long-chain derivatives do not have such properties. Synthetic phenolic antioxidants lacking the side hydrocarbon chains characteristic of natural antioxidants (tocopherols, ubiquinones, naphthoquinones) also cause Ca "leakage" through biological membranes.

In other words, short-chain antioxidants or antioxidants lacking side carbon chains, as a rule, have a weaker antioxidant effect and at the same time cause a number of side effects (disruption of Ca homeostasis, induction of hemolysis, etc.). However, the available data do not yet allow us to draw a final conclusion about the nature of the relationship between the structure of a substance and its antioxidant properties: the number of compounds with antioxidant properties is too large, especially since the antioxidant effect can be the result of not one, but a number of mechanisms.

The properties of any substance acting as an antioxidant (as opposed to their other effects) are non-specific, and one antioxidant can be replaced by another natural or synthetic antioxidant. However, a number of problems arise here related to the interaction of natural and synthetic lipid peroxidation inhibitors, the possibilities of their interchangeability, and the principles of replacement.

It is known that the replacement of effective natural antioxidants (primarily a-tocopherol) in the body can be carried out by introducing only those inhibitors that have high antiradical activity. But other problems arise here. The introduction of synthetic inhibitors into the body has a significant effect not only on the processes of lipid peroxidation, but also on the metabolism of natural antioxidants. The action of natural and synthetic inhibitors can be combined, resulting in an increase in the effectiveness of the impact on the processes of lipid peroxidation, but, in addition, the introduction of synthetic antioxidants can affect the reactions of synthesis and utilization of natural inhibitors of lipid peroxidation, and also cause changes in the antioxidant activity of lipids. Thus, synthetic antioxidants can be used in biology and medicine as drugs that affect not only the processes of free radical oxidation, but also the system of natural antioxidants, affecting changes in antioxidant activity. This possibility of influencing changes in antioxidant activity is extremely important, since it has been shown that all the studied pathological conditions and changes in cellular metabolism processes can be divided by the nature of changes in antioxidant activity into processes occurring at an increased, decreased, and stage-changed level of antioxidant activity. Moreover, there is a direct connection between the rate of development of the process, the severity of the disease, and the level of antioxidant activity. In this regard, the use of synthetic inhibitors of free radical oxidation is very promising.

Problems of gerontology and antioxidants

Given the involvement of free-radical mechanisms in the aging process, it was natural to assume the possibility of increasing life expectancy with the help of antioxidants. Such experiments were conducted on mice, rats, guinea pigs, Neurospora crassa and Drosophila, but their results are quite difficult to interpret unambiguously. The inconsistency of the data obtained can be explained by the inadequacy of the methods for assessing the final results, the incompleteness of the work, a superficial approach to assessing the kinetics of free-radical processes and other reasons. However, in experiments on Drosophila, a reliable increase in life expectancy was recorded under the influence of thiazolidine carboxylate and in some cases an increase in the average probable, but not actual life expectancy was observed. An experiment conducted with the participation of elderly volunteers did not give definite results, largely due to the impossibility of ensuring the correctness of the experimental conditions. However, the fact of an increase in life expectancy in Drosophila caused by an antioxidant is encouraging. Perhaps, further work in this area will be more successful. Important evidence in favor of the prospects of this direction is the data on the prolongation of the vital activity of the organs being treated and the stabilization of metabolism under the influence of antioxidants.

Antioxidants in clinical practice

In recent years, there has been a great deal of interest in free radical oxidation and, as a consequence, in drugs that can have a particular effect on it. Given the prospects for practical use, antioxidants attract particular attention. No less actively than the study of drugs already known for their antioxidant properties, a search is underway for new compounds that have the ability to inhibit free radical oxidation at different stages of the process.

The most studied antioxidants at present include, first of all, vitamin E. It is the only natural lipid-soluble antioxidant that breaks oxidation chains in human blood plasma and erythrocyte membranes. The content of vitamin E in plasma is estimated at 5 ~ 10%.

The high biological activity of vitamin E and, first of all, its antioxidant properties have led to the wide use of this drug in medicine. It is known that vitamin E has a positive effect in radiation damage, malignant growth, ischemic heart disease and myocardial infarction, atherosclerosis, in the treatment of patients with dermatoses (spontaneous panniculitis, nodular erythema), burns and other pathological conditions.

An important aspect of the use of a-tocopherol and other antioxidants is their use in various types of stress conditions, when antioxidant activity is sharply reduced. It has been established that vitamin E reduces the increased intensity of lipid peroxidation as a result of stress during immobilization, acoustic and emotional-pain stress. The drug also prevents liver disorders during hypokinesia, which causes increased free-radical oxidation of unsaturated fatty acids of lipids, especially in the first 4-7 days, i.e. during the period of pronounced stress reaction.

Of the synthetic antioxidants, the most effective is ionol (2,6-di-tert-butyl-4-methylphenol), clinically known as dibunol. The antiradical activity of this drug is lower than that of vitamin E, but its antioxidant activity is much higher than that of a-tocopherol (for example, a-tocopherol inhibits the oxidation of methyloleate by 6 times, and the oxidation of arachidone is 3 times weaker than ionol).

Ionol, like vitamin E, is widely used to prevent disorders caused by various pathological conditions occurring against the background of increased activity of peroxidation processes. Like a-tocopherol, ionol is successfully used to prevent acute ischemic organ damage and post-ischemic disorders. The drug is highly effective in the treatment of cancer, is used for radiation and trophic lesions of the skin and mucous membranes, is successfully used in the treatment of patients with dermatoses, promotes rapid healing of ulcerative lesions of the stomach and duodenum. Like a-tocopherol, dibunol is highly effective in stress, causing normalization of the increased level of lipid peroxidation as a result of stress. Ionol also has some antihypoxant properties (increases life expectancy during acute hypoxia, accelerates recovery processes after hypoxic disorders), which is also, apparently, associated with the intensification of peroxidation processes during hypoxia, especially during the reoxygenation period.

Interesting data were obtained when using antioxidants in sports medicine. Thus, ionol prevents the activation of lipid peroxidation under the influence of maximum physical loads, increases the duration of athletes' work under maximum loads, i.e. the body's endurance during physical work, increases the efficiency of the left ventricle of the heart. Along with this, ionol prevents disorders of the higher parts of the central nervous system that occur when the body is exposed to maximum physical loads and are also associated with free radical oxidation processes. Attempts have been made to use vitamin E and vitamins of group K in sports practice, which also increase physical performance and accelerate recovery processes, but the problems of using antioxidants in sports still require in-depth study.

The antioxidant effects of other drugs have been studied less thoroughly than the effects of vitamin E and dibunol, which is why these substances are often considered as a kind of standard.

Naturally, the closest attention is paid to preparations close to vitamin E. Thus, along with vitamin E itself, its water-soluble analogues also have antioxidant properties: trolax C and alpha-tocopherol polyethyleneglycol 1000 succinate (TPGS). Trolox C acts as an effective quencher of free radicals by the same mechanism as vitamin E, and TPGS is even more effective than vitamin E as a protector of CVS-induced lipid peroxidation. Alpha-tocopherol acetate acts as a fairly effective antioxidant: it normalizes the glow of blood serum, increased as a result of the action of prooxidants, suppresses lipid peroxidation in the brain, heart, liver and erythrocyte membranes under acoustic stress, and is effective in the treatment of patients with dermatoses, regulating the intensity of peroxidation processes.

In vitro experiments have established the antioxidant activity of a number of drugs, the action of which in vivo can be largely determined by these mechanisms. Thus, the ability of the antiallergic drug traniolast to dose-dependently reduce the level of O2-, H2O2 and OH- in a suspension of human polymorphonuclear leukocytes has been shown. Also in vitro, chloropromazine successfully inhibits Fe2+/ascorbate-induced lipid peroxidation in liposomes (by ~ 60%), and its synthetic derivatives N-benzoyloxymethylchloropromazine and N-pivaloyloxymethyl-chloropromazine slightly worse (by -20%). On the other hand, these same compounds, embedded in liposomes, when the latter are irradiated with light close to ultraviolet, act as photosensitizing agents and lead to the activation of lipid peroxidation. A study of the effect of protoporphyrin IX on peroxidation in rat liver homogenates and subcellular organelles also showed the ability of protoporphyrin to inhibit Fe- and ascorbate-dependent lipid peroxidation, but at the same time the drug did not have the ability to suppress autooxidation in a mixture of unsaturated fatty acids. A study of the mechanism of protoporphyrin's antioxidant action showed only that it is not associated with radical quenching, but did not provide sufficient data for a more precise characterization of this mechanism.

Using chemiluminescent methods in in vitro experiments, the ability of adenosine and its chemically stable analogs to inhibit the formation of reactive oxygen radicals in human neutrophils was established.

A study of the effect of oxybenzimidazole and its derivatives alkyloxybenzimidazole and alkylethoxybenzimidazole on the membranes of liver microsomes and brain synaptosomes during activation of lipid peroxidation showed the effectiveness of alkyloxybenzimidazole, which is more hydrophobic than oxybenzimidazole and, unlike alkylethoxybenzimidazole, has an OH group, which is necessary to provide antioxidant action, as an inhibitor of free radical processes.

Allopurinol is an effective quencher of highly reactive hydroxyl radical, and one of the products of the reaction of allopurinol with hydroxyl radical is oxypurinol, its main metabolite, an even more effective quencher of hydroxyl radical than allopurinol. However, the data on allopurinol obtained in different studies are not always consistent. Thus, a study of lipid peroxidation in rat kidney homogenates showed that the drug has nephrotoxicity, the cause of which is an increase in the formation of cytotoxic oxygen radicals and a decrease in the concentration of antioxidant enzymes, which causes a corresponding decrease in the utilization of these radicals. According to other data, the effect of allopurinol is ambiguous. Thus, in the early stages of ischemia, it can protect myocytes from the action of free radicals, and in the second phase of cell death - on the contrary, contribute to tissue damage, while in the recovery period it again has a beneficial effect on the recuperation of the contractile function of ischemic tissue.

Under conditions of myocardial ischemia, lipid peroxidation is inhibited by a number of drugs: antianginal agents (curantil, nitroglycerin, obzidan, isoptin), water-soluble antioxidants from the class of sterically hindered phenols (for example, phenosan, which also inhibits tumor growth induced by chemical carcinogens).

Anti-inflammatory drugs such as indomethacin, butadion, steroidal and non-steroidal antiphlogistic agents (in particular, acetylsalicylic acid) have the ability to inhibit free radical oxidation, while a number of antioxidants - vitamin E, ascorbic acid, ethoxyquin, dithiotrentol, acetylcysteine and diphenylenediamide have anti-inflammatory activity. The hypothesis that one of the mechanisms of action of anti-inflammatory drugs is the inhibition of lipid peroxidation looks quite convincing. Conversely, the toxicity of many drugs is due to their ability to generate free radicals. Thus, the cardiotoxicity of adriamycin and rubomycin hydrochloride is associated with the level of lipid peroxides in the heart, the treatment of cells with tumor promoters (in particular, phorbol esters) also leads to the generation of free-radical forms of oxygen, there is evidence in favor of the participation of free-radical mechanisms in the selective cytotoxicity of streptozotocin and alloxan - they affect pancreatic beta cells, abnormal free-radical activity in the central nervous system is caused by phenothiazine, lipid peroxidation in biological systems is stimulated by other drugs - paraquat, mitomycin C, menadione, aromatic nitrogen compounds, during the metabolism of which free-radical forms of oxygen are formed in the body. The presence of iron plays an important role in the action of these substances. However, today the number of drugs with antioxidant activity is much greater than that of prooxidant drugs, and it is not at all excluded that the toxicity of prooxidant drugs is not associated with lipid peroxidation, the induction of which is only the result of other mechanisms that cause their toxicity.

Undisputed inducers of free radical processes in the body are various chemical substances, and first of all heavy metals - mercury, copper, lead, cobalt, nickel, although this has been shown mainly in vitro, in in vivo experiments the increase in peroxidation is not very large, and so far no correlation has been found between the toxicity of metals and the induction of peroxidation by them. However, this may be due to the incorrectness of the methods used, since there are practically no adequate methods for measuring peroxidation in vivo. Along with heavy metals, other chemical substances also have prooxidant activity: iron, organic hydroperoxides, halogen hydrocarbons, compounds that break down glutathione, ethanol, and ozone, and substances that are environmental pollutants, such as pesticides, and substances such as asbestos fibers, which are products of industrial enterprises. A number of antibiotics (for example, tetracyclines), hydrazine, paracetamol, isoniazid and other compounds (ethyl, allyl alcohol, carbon tetrachloride, etc.) also have a prooxidant effect.

Currently, a number of authors believe that the initiation of free radical lipid oxidation may be one of the reasons for accelerated aging of the body due to numerous metabolic shifts described earlier.

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