Antioxidant protection

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The Oxygen Paradox

Everyone knows that oxygen is necessary for life, so everyone is afraid of oxygen starvation. In fact, it is impossible to live without oxygen, and even a slight decrease in the oxygen content in the air immediately affects our well-being and at the same time it is dangerous for living beings (this is the "oxygen paradox"). It is made dangerous by the same properties that made it so necessary.

All aerobic (oxygen-breathing) creatures obtain energy by oxidizing organic molecules with oxygen, and they all must protect themselves from the high oxidizing capacity of oxygen. Strictly speaking, oxidation is the same as combustion. It's just that in the body, substances "burn" gradually, step by step, releasing energy in small portions. If organic molecules burned quickly, like firewood in a stove, the cell would die from heat shock. After a molecule is oxidized, it changes. It is no longer the same molecule that it was before. For example, wood cellulose oxidizes to carbon dioxide and water during the combustion of firewood - it turns into smoke. The oxidation reaction can be imagined as taking something away. For example, if someone took your wallet on the street, you were "oxidized". In this case, the one who took possession of the wallet was "recovered". In the case of molecules, the oxidizing substance takes an electron from another substance and is restored. Oxygen is a very strong oxidizing agent. Even more powerful oxidizing agents are oxygen free radicals.

Free radicals

A free radical is a fragment of a molecule that has a high reactivity. An oxygen radical lacks an electron and seeks to take an electron from other molecules. When it succeeds, the radical becomes a molecule and leaves the game, but a molecule deprived of an electron becomes a radical and embarks on a path of robbery.

Molecules that were previously inert and did not react with anything now undergo the most bizarre chemical reactions. For example, two collagen molecules that have become free radicals, when confronted with oxygen radicals, become so active that they bind to each other, forming a dimer, while normal collagen fibers are unable to bind to each other. Cross-linked collagen is less elastic than normal collagen, and it is also inaccessible to matrix metalloproteinases (enzymes that break down old collagen so that newly synthesized collagen can take its place), so the accumulation of collagen dimers in the skin leads to wrinkles and a decrease in skin elasticity.

In a DNA molecule, even two parts of a single DNA strand can become radicals - in this case, they can bind to each other, forming crosslinks within one DNA molecule or between two DNA molecules. Crosslinks and other damage to DNA molecules cause cell death or their cancerous degeneration. No less dramatic is the outcome of a free oxygen radical encounter with enzyme molecules. Damaged enzymes can no longer control chemical transformations, and complete chaos reigns in the cell.

Peroxidation - what is it?

The most serious consequence of the appearance of free radicals in the cell is peroxidation. It is called peroxidation because its products are peroxides. Most often, unsaturated fatty acids, which make up the membranes of living cells, are oxidized by the peroxidation mechanism. In the same way, peroxidation can occur in oils that contain unsaturated fatty acids, and then the oil goes rancid (lipid peroxides have a bitter taste). The danger of peroxidation is that it occurs by a chain mechanism, i.e. the products of such oxidation are not only free radicals, but also lipid peroxides, which very easily turn into new radicals. Thus, the number of free radicals, and therefore the rate of oxidation, increases like an avalanche. Free radicals react with all biological molecules that they encounter on their way, such as proteins, DNA, lipids. If the avalanche of oxidation is not stopped, the entire organism may die. This is exactly what would happen to all living organisms in an oxygen environment if nature had not taken care to provide them with powerful protection - an antioxidant system.

Antioxidants

Antioxidants are molecules that can block free radical oxidation reactions. When an antioxidant encounters a free radical, it voluntarily gives it an electron and completes it into a full-fledged molecule. In doing so, antioxidants themselves turn into free radicals. However, due to the chemical structure of the antioxidant, these radicals are too weak to take an electron from other molecules, so they are not dangerous.

When an antioxidant gives its electron to an oxidizer and interrupts its destructive procession, it itself is oxidized and becomes inactive. In order to return it to a working state, it must be restored again. Therefore, antioxidants, like experienced operatives, usually work in pairs or groups in which they can support an oxidized comrade and quickly restore it. For example, vitamin C restores vitamin E, and glutathione restores vitamin C. The best antioxidant teams are found in plants. This is easy to explain, since plants cannot run away and hide from damaging effects and must be able to counteract. The most powerful antioxidant systems are found in plants that can grow in harsh conditions - sea buckthorn, pine, fir and others.

Antioxidant enzymes play an important role in the body. These are superoxide dismutase (SOD), catalase and glutathione peroxidase. SOD and catalase form an antioxidant pair that fights free oxygen radicals, preventing them from starting chain oxidation processes. Glutathione peroxidase neutralizes lipid peroxides, thereby breaking the chain lipid peroxidation. Selenium is necessary for glutathione peroxidase to function. Therefore, dietary supplements with selenium enhance the body's antioxidant defense. Many compounds have antioxidant properties in the body.

Despite powerful antioxidant protection, free radicals still have a fairly destructive effect on biological tissues, and in particular on the skin.

The cause of this is factors that dramatically increase the production of free radicals in the body, which leads to an overload of the antioxidant system and oxidative stress. The most serious of these factors is considered to be UV radiation, but excess free radicals can also appear in the skin as a result of inflammatory processes, exposure to certain toxins, or cell destruction.

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Antioxidants in cosmetics

Nowadays, few people doubt that the skin needs to be protected from free radicals. That is why antioxidants have become one of the most popular ingredients in cosmetics. But not every cream with antioxidants can protect our skin. Making a good antioxidant cocktail is a delicate matter; it is important to make a mixture in which different antioxidants will restore each other.

It is known, for example, that vitamin C restores vitamin E, but it is not so easy to create a cosmetic composition in which this antioxidant pair will work together. Vitamin E is fat-soluble, and vitamin C is water-soluble, so in a living cell they perform complex acrobatic tricks, meeting at the border of the membrane and cytoplasm. In addition, ascorbic acid is very difficult to introduce into cosmetic compositions, since it is easily destroyed. Currently, derivatives of ascorbic acid are used, which are more stable. For example, ascorbyl palmitate is fat-soluble, stable, and convenient for inclusion in the formulation during the preparation of the drug. In the skin, under the action of enzymes, palmitate (fatty acid) is split off from ascorbyl palmitate and ascorbate is released, which has biological activity. Two other derivatives are also used - magnesium ascorbyl phosphate and sodium ascorbyl phosphate. Both compounds are soluble in water and have good chemical stability. One option to create effective creams containing both vitamin C and vitamin E is to use liposomes. In this case, vitamin C is placed in an aqueous medium inside the liposome, and vitamin E is embedded in the fatty membrane of the liposome.

Ascorbic acid, which is so quickly destroyed in cosmetic creams, is preserved in vegetables and fruits. The same applies to other antioxidants. This means that antioxidant cocktails of plants are better composed than all artificial mixtures of antioxidants.

Indeed, the set of antioxidant substances in plants is much richer than in animal and human tissues. In addition to vitamins C and E, plants contain carotenoids and flavonoids (polyphenols). The word "polyphenol" is used as a general generic name for substances that have at least two adjacent hydroxyl groups in the benzene ring. Due to this structure, polyphenols can serve as a trap for free radicals. The polyphenols themselves are stable, entering into polymerization reactions. Flavonoids have very strong antioxidant properties, and in addition, they maintain vitamins C and E in an active state and protect them from destruction. Since all plants need to fight free radicals, there is no plant whose extract would not have antioxidant properties (that is why it is so useful to eat vegetables and fruits). And yet there are plants that contain the most successful antioxidant sets.

Several years ago, it was shown that regular consumption of green tea significantly reduces the risk of developing malignant tumors. The scientists who made this discovery were so shocked by it that they have since started drinking several cups of green tea a day. It is not surprising that green tea extract has become one of the most popular plant antioxidants in cosmetics. Purified green tea polyphenols have the most pronounced antioxidant effect. They protect the skin from the harmful effects of UV radiation, have a radioprotective effect, and relieve skin irritation caused by harmful chemicals. Green tea polyphenols have been found to inhibit the enzyme hyaluronidase, due to the increased activity of which the amount of hyaluronic acid in aging skin decreases. Therefore, green tea is recommended to be included in products for aging skin.

Recently, scientists have made many interesting discoveries by analyzing statistics on cardiovascular and oncological diseases in various countries. For example, it turned out that Mediterranean peoples who consume a lot of olive oil are less susceptible to oncological diseases, and Eastern cuisine serves as excellent protection against cardiovascular diseases and hormone-dependent tumors. Since free radicals play a large role in the development of tumors and cardiovascular diseases, such observations have allowed scientists to discover many new antioxidants.

For example, it is known that beautiful France, which daily consumes incredible quantities of wine, has very favorable statistics on cardiovascular and oncological diseases. There was a time when scientists explained the "French paradox" by the beneficial effects of small doses of alcohol. Then it was discovered that the ruby color of noble red wines is explained by the high content of flavonoids - the most powerful natural antioxidants.

In addition to flavonoids, which can be found in other plants, red grapes contain a unique compound called resveratrol, which is a powerful antioxidant, prevents the development of certain tumors, atherosclerosis, and slows down skin aging. Some scientists, imbued with faith in the healing properties of wine, recommend drinking up to 200-400 ml of red wine per day. However, before following this recommendation, you should take into account that in this case we mean very high-quality wine obtained by fermenting pure grape juice, and not surrogates.

Vitamin E, which remains the most important antioxidant, can also be introduced into cosmetics not in pure form, but as part of vegetable oils. A lot of vitamin E is found in oils: soybean, corn, avocado, borage, grape, hazelnut, wheat germ, rice bran.

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How many antioxidants do you need?

The question arises: if antioxidants are so useful, shouldn't they be introduced into cosmetics in higher concentrations? It turns out that the formula "the more, the better" does not work with antioxidants, and they, on the contrary, are most effective in fairly low concentrations.

When there are too many antioxidants, they turn into their opposite - they become prooxidants. This raises another problem - does the skin always need additional antioxidants or can adding extra antioxidants disrupt the skin's natural balance? Scientists argue about this quite a lot, and there is no final clarity on this issue. But we can definitely say that antioxidants are necessary in a day cream that does not penetrate beyond the stratum corneum. In this case, they act as a shield that reflects external attacks. It is always useful to apply natural oils to the skin, which contain antioxidants in precisely calibrated concentrations by nature, as well as to eat fresh vegetables and fruits or even drink an occasional glass of good red wine.

The use of nourishing creams with antioxidant action is justified in the event that the load on the natural antioxidant systems of the skin suddenly increases; in any case, it is preferable to use creams that contain natural antioxidant compositions - plant extracts rich in bioflavonoids, vitamin C, natural oils containing vitamin E and carotenoids.

Are antioxidants really effective?

There is an ongoing debate among scientists about whether the benefits of antioxidants are exaggerated and whether cosmetics with antioxidants are really good for the skin. Only the immediate protective effect of antioxidants has been proven - their ability to reduce damage to the skin by UV radiation (for example, to prevent sunburn), to prevent or reduce the inflammatory reaction. Therefore, antioxidants are undoubtedly useful in sunscreens, day creams, as well as in products used after various skin damages - shaving, chemical peeling, etc. Scientists are less confident that regular use of antioxidants can really slow down aging. However, this possibility cannot be denied. It is important to understand that the effectiveness of antioxidants depends on how well the antioxidant cocktail is composed - the mere presence of the names of antioxidants in the recipe does not mean that the product will be effective.

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