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Application of tannic acid, how much do you know?

Tannic acid belongs to hydrolyzed tannins, which can be hydrolyzed to acid and glucose. It is one of the earliest studied tannins and has strong biological and pharmacological activities. Tannic acid is mainly rich in plants such as Chinese five seeds, Turkish seeds, tara pods, pomegranates, sumac leaves, sumac, and witch hazel trees. Among them, Wuzi is a special forest product in China, which is mainly distributed in Qinling Mountains, Bashan Mountains, Wudang Mountains and other regions with unique climate and soil conditions.

Table of Tannic Acid

What is tannic acid?

Tannic acid is an unique form of tannin as well as a polyphenol. Its weak acidity (pKa is about 6) results from a lot of phenolic teams in its framework. The chemical formula of commercial tannic acid is generally C76H52O46, which represents decagalloyl glucose, yet in fact it is a combination of polyglycidyl glucose or polyglycidyl quinoate and also gallic acid number. The part of each molecule varies from 2 to 12, depending upon the plant source utilized to remove tannic acid. Business tannins are normally removed from any one of the following plant components: tara capsules, gallnuts from lacquer trees or Quercus infectia or Sicilian lacquer leaves.

According to the meanings of external referrals such as the International Pharmacopoeia, the Codex Alimentarius, and the FAO – WHO monograph on tannin, just tannins drawn out from the above plants can be considered as tannin. Often the extract of chestnut or oak is also described as tannin, however this is the incorrect use of the term. It is a yellow to light brown amorphous powder.

Although tannic acid is an unique kind of tannin (plant polyphenol), both terms can in some cases (mistakenly) be utilized interchangeably. The long-lasting abuse of these terms as well as their look in academic short articles have actually exacerbated the confusion. This is particularly common in green tea and also black tea, both of which contain many different sorts of tannins, not simply tannins.

Tannic acid is not the suitable requirement for tannin evaluation of any kind of type, due to the fact that its structure is not clearly specified.

Application of tannic acid

The effect of tannic acid

  1. Anti-wrinkle effect
    As we age, the collagen in the skin cross-links and the structure becomes firmer and less elastic. Elastin is the most important fibrous protein to maintain skin elasticity. The decline or denaturation of its content is the main reason for the formation of skin wrinkles. Tannin can promote cell metabolism, maintain the vitality of elastin, and keep the skin healthy, shiny and elastic.
  2. Resist UV rays
    Tannin is a kind of natural substance that has a strong absorption in the ultraviolet light area. Tannin is called a “ultraviolet filter” and has an absorption rate of more than 98% for ultraviolet rays. It is effective for sunburn and various pigmentation. It has obvious defense effect.
  3. Whitening effect
    The color of the skin is mainly determined by the content of melanin. Tannin can reduce and decolorize melanin, and can also effectively remove active oxygen, so tannin has a comprehensive whitening effect.
  4. Moisturizing effect
    The healthy appearance of the skin depends on the moisture content of the stratum corneum, and chronic dehydration can lead to rough skin and the formation of wrinkles. The molecular structure of tannin contains a large number of hydrophilic groups — phenolic hydroxyl groups. It is easy to absorb moisture in the air, so it has a moisturizing effect.
  5. Antiseptic effect
    Tannin has obvious inhibitory ability to a variety of bacteria, fungi and microorganisms, and at the same inhibitory concentration, it will not affect the growth and development of human cells. Tannin also has unique antioxidant properties, which can effectively resist biological oxidation and remove active oxygen, so tannin can effectively inhibit bacteria and have health care and antiseptic effects.

The function of commercial tannins as well as medicinal tannins

Tannic acid is primarily utilized as a mordant in dyeing, as well as is also used to prepare gallic acid as well as pyrogallic acid. It can also be made use of to manufacture leather tanning agents, rubber coagulants, healthy protein as well as alkaloid precipitation agents, as well as to determine beryllium, aluminum, nickel, Reagents for steels such as copper. The light yellow to light brown amorphous powder acquired by evaporating and also drying out the water extract of gallnut is industrial tannic acid, which includes more than 80% tannic acid, and also includes a small amount of gallic acid, metagallic acid, as well as trigallic acid. Acid and also pentaacylglucose, and so on. Tannic acid is based upon 1,3,4,6-tetra-O-galloyl-2-poly-O-galloyl- β-D sugar as the core, and also is composed of 1 particle of sugar incorporated with 8 to 9 gallic acids made esters. Tannic acid is quickly hydrolyzed by acid or enzyme, as well as the hydrolyzed items are gallic acid as well as sugar.

  1. As raw material of gallic acid and also pyrogallic acid.
  2. Mordant. Utilized for fiber fixation or dyeing, as a salt-based dye.
  3. Ore flotation representative. Rare-earth element smelting, extraction of germanium from lead-zinc ore or dirt, removal of rare metals such as thorium and polonium from solution, extraction of lead as well as copper from chalcopyrite.
  4. Conversion finish. Aluminum and its alloy plate, steel, copper, zinc surface rust security, and so on
  5. Food additives. Such as food antioxidants, drink clarifiers, progressed inks and also printing inks.
  6. Drilling mud thinner.
  7. Synergist. Synthesis of 2,4-diamino-5-(3,4,5-trimethoprim) (trimethoprimam), described as TMP or sulfonamide synergist.
  8. Deodorant. Used in refrigerators, storehouses, and toilets to get rid of ammonia and also various other odors. In addition, tannic acid can likewise be used to manufacture Keguandiamine, Keguanzhuo as well as other heart disease medications; synthesize bifendate to treat liver disease B; manufacture antimony-273 to treat schistosomiasis.
Tannic Acid

Tannic acid can prevent the growth of germs and also the absorption of intestinal tract toxic substances, as well as can be used to prevent and treat diarrhea. Medical tannic acid can be directly utilized in drinks, icy products, sweets, ice cream, and also meat products; it can be made use of as an astringent for burns as well as scald injuries, and also a gastrointestinal hemostatic representative to stop infection; Ointment, anti-cold representative (N-diamidinomorpholine tannate), wellness marketer, bug spray, insecticide, radiation protection agent, contraceptive representative as well as special toothpaste, etc.

Tannic Acid

Application of tannic acid

Tannic acid has a strong inhibitory effect on streptococci, and 0.25 g/L of tannic acid can achieve a 100% inhibitory rate. At the same time, tannic acid can also inhibit the activity of gingival hyaluronidase and collagenase, so adding tannic acid in toothpaste can prevent gum disease and periodontitis, and has the function of anti-caries. Tannic acid has strong ultraviolet absorption characteristics, especially in the far ultraviolet region with high energy and great destructive power (λmax =263 nm, ε=8350).

In addition, tannic acid has a strong inhibitory effect on the Maillard reaction that easily causes skin aging, so tannic acid can be used as an active ingredient in sunscreen and anti-aging in cosmetics. Cosmetics prepared by using the astringent properties of tannic acid are non-irritating to the skin, have a moderate astringent effect, and have good moisturizing properties. For example, mix 50 g of SiO2 with 45 g of 10% elastin aqueous solution, then mix with 5 g of 50% tannic acid aqueous solution at 40 °C, dry in vacuum, grind into powder and then dry, the obtained porous The elastin-tannin complex can be used as a cosmetic skin care component.

In addition, tannic acid used in cosmetics can also improve skin color, strengthen blood circulation and promote hair growth. Under the action, it can maintain a delicate, white and tender complexion. The germanium-containing tannin and water-soluble iron salt can be used to make black hair dye. The self-oxidizing hair dye prepared by acid, tannin and diamine derivatives is safe to use, with high color fastness and natural hair after treatment.

The pharmacological activity of tannic acid is a comprehensive reflection of its interaction with biological proteins, enzymes, polysaccharides, nucleic acids, etc., as well as its anti-oxidation and complexation with metal ions.

In traditional prescriptions, catechin cream mainly containing tannic acid and catechin tannins are often used as hemostatic agents for wounds and burns because of their astringent properties, and because they have a certain antibacterial effect, they can protect wounds. Department, to prevent wound infection and inflammation. Tannic acid can also be used as an antidote when alkaloids and some heavy metal ions are poisoned, because it can be chelated with it to form a precipitate, reducing the absorption of the body, and the complexation of tannic acid with calcium ions outside cells or tissues, It can resist the contraction induced by smooth muscle calcium and lower blood pressure. For example, glycerin (5-10 parts), sunflower oil (5-10 parts), and tannic acid (1-5 parts) can be formulated into quick-acting antihypertensive drugs .

The antimutagenic, antitumor and anticancer properties of tannic acid have aroused great interest of pharmacists. Studies have shown that tannic acid and tea tannins have a good inhibitory effect on chemically induced skin, lung, and forestomach tumors. For example, pretreatment of mouse skin with tannic acid can inhibit the early activity of (±)-7β,8α-dihydroxy-9α,10β-epoxy-7,8,9,10-tetrahydrophenylpyrene-induced skin tumors , also inhibited the growth of chemically induced SENCAR mouse skin tumors in the early and middle stages. Gali in the United States studied the anticancer effect of tannic acid extracted from sumac leaves, five seeds and tara fruit pods in mice. These tannic acids can hinder the induction of ornithine decarboxylase and the production of peroxides to varying degrees, and improve the anti-oxidation and anti-cancer effects in mice. Anti-AIDS research on tannins is of great interest due to their higher activity and lower toxicity compared to synthetic anti-AIDS virus (AIDS) drugs.

Edible tannins can be used as clarifiers and stabilizers for beverages and wines, and can also be combined with plant fibers to form solidified tannins, which can be used as filter adsorbents for wines, iron removal and decolorization of soybean soy sauce.

The Sichuan Academy of Forestry has developed a solidified tannin with plant cellulose as the carrier and penta tannic acid as the ligand, which is used for iron removal in the production of fruit wine and liquor, and the iron removal efficiency can reach more than 90%. Adding Wuzi tannin 6 g/100 L to wort and beer can reduce high molecular nitrogen in wort by 5 mg/100 mL, reduce the formation of diacetyl, and improve the colloidal stability and taste stability of beer. Tannic acid has a good function of trapping free radicals due to its phenolic hydroxyl group, and can be used as a food antioxidant.

For example, food-grade tannic acid is used instead of SO2 as wine antioxidant, and the aroma components are analyzed by gas chromatography, which proves that tannic acid is a good wine preservative. However, due to the strong hydrophilicity of tannic acid, although it has strong oxidation resistance in the water phase, it cannot reflect its superiority in the oil phase due to the barrier of solubility.

Before the 1970s, Tara tannic acid was mainly used as a leather tanning agent. Tanned leather with Tara tannin, the finished leather is light, soft, elastic, and has a good color, which is comparable to lacquer leaf. Experiments have shown that the tanning effect of tara tannin is similar to that of excellent wattle extract. Leather products tanned with tara tannin have the characteristics of light color, non-fading, hard texture and smoothness. Due to the good tanning properties of tara tannin, it is recommended as lacquer extract, catechu extract, The substitute of wattle extract is a promising tanning material. Moreover, the tanned leather with tara tannin is only obtained from the fruit, fruit pods or leaves, and there is no need to cut down trees, and its resources can be used sustainably.

Tannic acid can be used as an effective inhibitor of calcium and magnesium minerals in ore flotation process. Tannic acid interacts with the mineral surface through chemical adsorption, hydrogen bond force and electric double layer electrostatic force, etc., and has a strong competitive adsorption with the collector on the mineral surface, or the collector is decomposed from the mineral surface. Tannic acid molecules adsorbed on the mineral surface contain a large amount of -OH and -COOH, which can make the mineral surface hydrophilic. Using dodecylamine as a collector and tannic acid as a regulator can effectively separate wollastonite and diopside. Using Auger electron spectroscopy, it was found that the binding energy of Ca2p on the surface of diopside is higher than that of limestone. -OH in nic acid and -COO- obtained by hydrolysis are more likely to combine with Ca2 + on the surface of diopside. Fang Xihui et al. used single minerals to study the effects of tannic acid, calcium hypochlorite and their combined agents on the flotation behavior of pyrite and chalcopyrite. The results showed that at about pH 9.5, tannic acid and The combined agent of calcium hypochlorite is technically feasible and can realize the separation of copper and sulfur under low alkali conditions. In addition, tannic acid is also the best precipitating agent in the wet germanium extraction process, and the germanium precipitation rate can reach more than 90%.

According to the property of tannic acid to chelate many metal ions, tannic acid can be used as a descaling agent for boilers and heat exchangers. Tannic acid complexes with Ca2+ and Mg2+ in the water, thereby reducing the hardness of the water and softening the water in the boiler. The complexes can further form large-sized mud deposits and be discharged with the sewage. In addition, tannic acid can also form a dense film with the metal pipe wall to passivate it, which plays a protective role and prevents the corrosion of pipes and boilers. In water treatment, tannin can also be used to purify waste water containing protein and surfactant, so that flocs can be precipitated and then removed, so as to reduce COD and avoid the foul smell of protein organic matter in water. Tannin can also recover ultrafine precious metal powder in aqueous solution. For example, sewage containing 3 g/L silver powder is treated with 10 g/L gelatin and 10 g/L tannic acid, stirred, left standing and filtered, and the filter cake is dried and heated to 900 Decomposition at ℃ can obtain silver with a purity of 90%.

Tannic acid, gallic acid, etc. can be used as anti-rust and anti-corrosion agents for ferrous metals (iron, steel) used in industry, construction, watercraft and seaport equipment. The ortho phenolic hydroxyl group in the tannic acid molecule can react with Fe3+ in the rust to form a black stable and dense chelate-iron tannin, which firmly covers the steel surface, thereby preventing the development of rust, and the tannin The ability to absorb oxygen also plays a role in preventing the oxidation of the steel surface, and can also inhibit the reproduction of iron-phagic bacteria. Wang Jikui et al. treated the surface of A3 steel with tannic acid solution, and obtained a uniform blue film with obvious corrosion resistance. The suitable process conditions were concentration 4 g/L, temperature 20, pH 3.5, and treatment time 60 seconds. It is found by scanning electron microscope that tannic acid and Fe3 + form an amorphous complex film with a network structure. The film layer is uniform and the color is bright, which has a good application prospect.

Reference

  1. “Food Additive Status List (GRAS); listing for tannic acid”. US Food and Drug Administration.
  2. Ma Zhihong, Lu Zhongbing, Shi Bi. Chemical Properties and Applications of Tannic Acid [J]. Natural Products Research and Development, 2003, 15(1): 87-91.
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