Everyone knows that oxygen is essential 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 instantaneously affects our health and at the same time it is dangerous for living things (this is the "oxygen paradox"). The same properties that made him so necessary also make it dangerous.
All aerobic (oxygen-breathing) creatures receive energy by oxidizing organic molecules with oxygen, and all of them must be protected from the high oxidizing ability of oxygen. Strictly speaking, oxidation is the same burning. Just in the body, substances "burn" gradually, in stages, releasing energy in small portions. If organic molecules burned quickly, like wood in the oven, then the cell would die from heat shock. After the molecule is oxidized, it changes. This is not the molecule that was before. For example, wood pulp is oxidized to carbon dioxide and water in the process of burning wood - it turns into smoke. The oxidation reaction can be imagined as the selection of something. For example, if you took away your wallet on the street, then you were "oxidized". In this case, the one who took possession of the wallet, "recovered." In the case of molecules, the oxidizing substance takes the electron from another substance and is restored. Oxygen is a very strong oxidizer. Even more powerful oxidants are free radicals of oxygen.
A free radical is a fragment of a molecule that has a high reactivity ability. The oxygen radical lacks an electron, and it tends to take an electron from other molecules. When it succeeds, the radical becomes a molecule and leaves the game, but the molecule deprived of an electron becomes a radical and embarks on the path of robbery.
Molecules that used to be inert and reacted with no one are now entering the most bizarre chemical reactions. For example, two collagen molecules that have become free radicals, encountering oxygen radicals, become so active that they bind together to form a dimer, while normal collagen fibers are not able to communicate with each other. Cross-linked collagen is less elastic than conventional collagen, and besides, it is inaccessible to matrix metalloproteinases (enzymes that destroy old collagen so that it's replaced by newly synthesized collagen), so accumulation of collagen dimers in the skin leads to wrinkles and reduced skin elasticity.
In the DNA molecule, radicals can become even two parts of a single strand of DNA - in this case they can communicate with each other, forming cross-links within one DNA molecule or between two DNA molecules. Crosslinks and other damages in DNA molecules cause death of cells or their cancer degeneration. The meeting of a free oxygen radical with enzyme molecules ends no less dramatically. Damaged enzymes can no longer control chemical transformations, and complete chaos sets in in the cell.
Peroxide oxidation - what is it?
The most serious consequence of the appearance of free radicals in the cell is peroxide oxidation. Peroxide it is called because its products are peroxide. Most often, the peroxide mechanism oxidizes unsaturated fatty acids, of which the membranes of living cells are composed. Similarly, peroxidation can occur in oils that contain unsaturated fatty acids, and then the oil rips (the lipid peroxides have a bitter taste). The danger of peroxidation is that it flows through a chain mechanism, i.e. Products of this oxidation are not only free radicals, but also lipid peroxides, which are very easily converted into new radicals. Thus, the amount of free radicals, and hence the rate of oxidation, increases in an avalanche manner. Free radicals react with all the biological molecules that they encounter on the way, such as proteins, DNA, lipids. If the avalanche of oxidation does not stop, then the whole organism may die. This is what would happen to all living organisms in the oxygen environment, if nature did not take care to supply them with a powerful defense - an antioxidant system.
Antioxidants are molecules that are capable of blocking the reactions of free radical oxidation. Meeting with a free radical, the antioxidant voluntarily gives it an electron and complements it to a full molecule. In this case, the antioxidants themselves become free radicals. However, due to the peculiarities of the chemical structure of the antioxidant, these radicals are too weak to take an electron from other molecules, so they are not dangerous.
When the antioxidant gives up its electron to the oxidizer and interrupts its destructive procession, it oxidizes itself and becomes inactive. In order to return it to the 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 companion and quickly restore it. For example, vitamin C restores vitamin E, and glutathione restores vitamin C. The best antioxidant commands are found in plants. This is easily explained, since plants can not escape and hide from damaging effects and must be able to resist. The most powerful antioxidant systems are plants that can grow in harsh conditions - sea buckthorn, pine, fir and others.
An important role in the body is played by antioxidant enzymes. This is a 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, thus breaking the chain lipid peroxidation. For the work of glutathione peroxidase, selenium is needed. Therefore, dietary supplements with selenium enhance the antioxidant defense of the body. Many compounds possess antioxidant properties in the body.
Despite the powerful antioxidant protection, free radicals still have a sufficiently destructive effect on biological tissues, and in particular on the skin.
The reason for this are factors that dramatically increase the production of free radicals in the body, which leads to an overload of the antioxidant system and to oxidative stress. The most serious of these factors is UV radiation, but an excess of free radicals can appear in the skin and due to inflammation, exposure to certain toxins or cell destruction.
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Antioxidants in cosmetics
Now very few people doubt that the skin should be protected from free radicals. Therefore, antioxidants have become one of the most popular ingredients in cosmetics. But not every cream with antioxidants can protect our skin. Drawing up 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 to create a cosmetic composition in which this antioxidant pair will work together is not so simple. 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 easily breaks down. At present, ascorbic acid derivatives are used which are more stable. For example, ascorbyl palmitate - fat-soluble, stable, convenient for inclusion in the formulation during preparation. In the skin, the palmitate (fatty acid) is cleaved by ascorbyl palmitate enzymes and ascorbate, which has biological activity, is released. Two other derivatives are also used: magnesium ascorbylphosphate and sodium ascorbyl phosphate. Both compounds are soluble in water and have good chemical stability. One way 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 liposomes and vitamin E is inserted into the fatty shell of liposomes.
Ascorbic acid, which is so quickly destroyed in cosmetic creams, is stored in vegetables and fruits. The same goes for other antioxidants. This means that the antioxidant cocktails of plants are made better than all artificial mixtures of antioxidants.
Indeed, a 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 generic generic name for substances having at least two adjacent hydroxyl groups in the benzene ring. Thanks to this structure, polyphenols can serve as a trap for free radicals. The polyphenols themselves are stable in this case by entering the polymerization reaction. Flavonoids have very strong antioxidant properties, and in addition, they maintain in an active state and protect against destruction, vitamins C and E. Since the need to fight free radicals is in front of all plants, there is no such plant, the extract of which does not possess antioxidant properties so it is useful to eat vegetables and fruits). And yet there are plants that contain the most successful antioxidant kits.
Several years ago it was shown that regular consumption of green tea significantly reduces the risk of malignant tumors. The scientists who made this discovery were so shocked by him that since then they began to drink several cups of green tea a day. It is not surprising that the extract of green tea has become one of the most popular herbal antioxidants in cosmetics. The most pronounced antioxidant effect is possessed by purified polyphenols of green tea. They protect the skin from the harmful effects of UV radiation, have a radioprotective effect, remove skin irritation caused by the action of harmful chemicals. It has been found that green tea polyphenols inhibit the enzyme hyaluronidase, because of the increased activity of which in the aging skin the amount of hyaluronic acid decreases. Therefore, green tea is recommended for administration in the remedies for aging skin.
Recently, scientists have made many interesting discoveries, analyzing the statistics of cardiovascular and oncological diseases in various countries. For example, it turned out that the Mediterranean peoples, consuming a lot of olive oil, are not very susceptible to oncological diseases, and the Oriental cuisine is an excellent protection against cardiovascular diseases and hormone-dependent tumors. Since free radicals play an important role in the development of tumors and cardiovascular diseases, similar observations have allowed scientists to discover many new antioxidants.
For example, it is known that a beautiful France, absorbing extraordinary quantities of wine every day, has very favorable statistics on cardiovascular and oncological diseases. There was a time when scientists explained the "French paradox" 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 in them - the strongest natural antioxidants.
In addition to flavonoids, which can be found in other plants, the red grapes contain a unique compound resveratrol, which is a powerful antioxidant, prevents the development of certain tumors, atherosclerosis, slows the aging of the skin. Some scientists, imbued with faith in the medicinal properties of wine, recommend drinking up to 200-400 ml of red wine per day. True, before following this recommendation, it should be taken into account that in this case we mean a very high-quality wine, obtained by fermentation of pure grape juice, and not surrogates.
Vitamin E, which remains the most important antioxidant, can also be introduced into cosmetics not in its pure form, but in vegetable oils. A lot of vitamin E is found in oils: soybean, corn, avocado, borage, grapes, hazelnut, wheat germ, rice bran.
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How much antioxidants do you need?
The question arises: if antioxidants are so useful, do not you need to inject them into cosmetics in high concentrations? It turns out that the formula "the more, the better" for antioxidants does not work, and they, on the contrary, are most effective at low enough concentrations.
When antioxidants are too much, they turn into their opposite - they become pro-oxidants. Hence, another problem arises: do skin always need additional antioxidants or if adding excessive antioxidants can disrupt the natural balance of the skin? Scientists argue about this quite a lot, and there is no final clarity on this issue. But you can definitely say that in day cream, which does not penetrate the stratum corneum, antioxidants are needed. In this case, they play the role of a shield that reflects external attacks. It is always useful to apply to the skin natural oils that contain antioxidants in precisely adjusted concentrations, as well as consume fresh vegetables and fruits or even drink a glass of good red wine.
The use of antioxidant nutritional creams is justified if the load on natural antioxidant systems of the skin suddenly increases. In any case, it is preferable to use creams containing natural antioxidant compositions - herbal extracts rich in bioflavonoids vitamin C, natural oils containing vitamin E and carotenoids .
Are antioxidants effective?
Among scientists, there is still debate about whether the usefulness of antioxidants is not exaggerated, and whether cosmetics with antioxidants are really useful for the skin. Only the immediate protective effect of antioxidants is shown - their ability to reduce skin damage by UV radiation (for example, to prevent sunburn), to prevent or reduce the inflammatory response. Therefore, antioxidants are undoubtedly useful in sunscreen compositions, day creams, and also in products used after various skin damages, such as shaving, chemical peeling, etc. Less confidence among scientists is that, by regularly applying antioxidants, you can really slow down aging. However, this possibility can not be denied. It is important to understand that the effectiveness of antioxidants depends on how well the antioxidant cocktail is properly composed, the mere presence of antioxidant names in the recipe does not yet mean that the remedy will be effective.
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