Chemical and Biological Basis of Tannin 1 Slow Physiological Activity
The physiological activity of tannin is the final embodiment of its interaction with protein, polysaccharide and nucleic acid in organisms, and these interactions depend on its molecular structure. According to chemical structure, tannins can be divided into hydrolyzed tannins and condensed tannins L3i. The former refers to polyphenols formed by phenolic acid or its derivatives and glucose or yeast mainly through ester magnesium, which can be hydrolyzed into simpler compounds under the action of dilute acid, dilute alkali and bacteria, and can also be divided into acid-free tannins (which can be hydrolyzed to form acid-free tannins) and acid-free tannins (which can be converted into spironolactone acids after hydrolysis). Traditional medicinal plants mostly contain hydrolyzed tannins, such as five kinds for hemostasis and anti-inflammation. Condensed tannin is a polymer (more than three monomers) of light flavan -3- alcohol (its derivative is called catechin) and light flavan -3,4-diol (its derivative is called leucoanthocyanidin). It cannot be hydrolyzed, but it is oxidized and dehydrated under the action of acid and reducing bacteria, and condensed into a reddish-brown "spiral red" precipitate, which is insoluble in water. Tannins contained in food are mainly condensed tannins, and cut apples, plums and tea leaves will form "snail red" if they are left for a long time. Tannin in green tea is the precursor of tannin and belongs to catechin and its derivatives. When fermented into black tea, it is oxidized and concentrated into theaflavins, thearubigins, brassinolide and so on. It has the property of condensed tannin. Oligomeric tetanus acid is absorbed into the blood through microvessels, which has antioxidant effect, while multimers (more than three monomers) cannot be absorbed, excreted or left in the gastrointestinal tract. This group has strong binding force with protein, which protects the stomach wall from alcohol and hydrochloric acid.
Tannin contains many phenolic groups and has a wide cross section suitable for hydrophobic association with protein. It forms magnesium by cross-linking with imino group in protein, instead of connecting with magnesium hydroxide in water, which shows sulfur-based water and precipitation. This is its important quality printing convergence, which is related to molecular weight (cangue). 3 delete), although the convergence of hydrolyzed tannins is greater than that of condensed tannins. The astringency of hydrolyzed tannins is directly related to the content of hydrophobic groups, while condensed tannins are related to the degree of polymerization. The bigger the fatty group of protein amino acid, the stronger its hydrophobicity, the better its combination with tannin, and the more it precipitates at its isoelectric point. Tannin combines with water-soluble protein (such as saliva protein) to precipitate, which makes saliva lose lubricity and the epithelial tissue of tongue contract, making it feel dry and produce astringent taste. Combined with insoluble protein (such as fibrin), it increases physical and chemical stability and is used for screwing screws.
Study on physiological activity of tannin 2 and its effect on flowering status of cherry blossoms
Things often have two sides. Tannin has dual effects on human body. What is important is how to use it reasonably, how to transform it and avoid negative effects.
2. Adverse effects of1tannin on human body
Too much tannin in food will produce some anti-nutritional effects.
2. 1. 1 Reduce the nutritional value of protein: Tannin forms an indigestible complex with dietary protein in the digestive tract instead of directly inhibiting the activity of digestive enzymes. Long-term consumption of tannin-containing feed for laying hens will reduce feed utilization and egg laying rate, increase mortality c2. 1.2, and affect the absorption of iron and calcium. Tannin will compound with minerals such as iron and calcium in the digestive tract, thus reducing its absorption. Vc can reduce trivalent iron to divalent iron, which has high solubility at physiological pH and low affinity with inhibitors, which is helpful to improve the bioavailability of food components.
2. 1.3 affects the effective utilization of VA and Vb 12. As far as the daily diet (including animal protein and cereals such as rice, wheat and corn) is concerned, although it contains tannin, it will not cause nutritional problems. People in semi-arid areas of Asia and Africa will be short of nutrition because they often eat foods with high tannin content such as sorghum, millet and beans.
2.2 The positive effects of tannins on human body in traditional medicine. Tannin is used for treating gastrointestinal bleeding and dysentery, and for local hemostasis and wound protection to prevent infection and inflammation. Recent research shows that tannin has many important functions for organisms besides antibacterial and healing, which opens up a new page for the utilization of tannin.
2.2. 1 antibacterial and antiviral tannins can coagulate protoplasm in microorganisms and act on a variety of enzymes, so they have obvious inhibitory effects on cholera, Escherichia coli, Staphylococcus aureus and other bacteria. Bacteria in the oral cavity secrete glycosyltransferase to promote the synthesis of dextran from sucrose. Bacteria adhere to the surface of teeth to form tartar, which leads to tooth decay. Tannin in tea and areca catechu can prevent the adsorption and growth of Streptococcus on the tooth surface, inhibit the expression and synthesis of glycosyltransferase, and thus reduce the formation of dental caries. In Japan, the corresponding extract products have been used as raw materials and deodorants for anticaries candy. The antiviral property of tannin is similar to antibacterial activity, and it has the function of "clearing away heat and toxic materials". Tannin from spirulina platensis has obvious antiviral effect, and its ability can be increased by increasing the degree of acylation and polymerization. Some people think that Dohia may be the only virus killer in nature. At present, the research of tannin against AD5 virus and HIV has attracted people's attention.
2.2. 1 Some undigested small molecules (from protein) in antiallergic food are allergens of special people, and their bodies produce specific antibodies against I, and produce and release chemical mediators, thus causing allergies. Known antiallergic factors include polyunsaturated fatty acids, water-soluble fibers, pectin, chitosan, polyphenols and so on. The anti-allergic mechanism of polyphenols is to inhibit the release of chemical mediators such as histamine. E 12CG, EGC, ECG, EC and caffeic acid in tea can all inhibit allergic components, among which EGCG has the strongest activity. The anti-allergic effect of sweet tea is also excellent, and clinical trials show that it has remarkable curative effect on many allergic patients. It was confirmed by analysis that its unique component, E 1-Junkou mZH polyMr, has very strong anti-allergic activity, and the anti-allergic activity is directly proportional to the degree of polymerization.
2.2.3 Antioxidant and anti-aging tannins are easier to oxidize than original tannins, and will accelerate oxidation in the presence of enzymes, air, water and alkalinity. Low molecular weight tea polyphenols (evaluation) and gallic acid, the degradation product of tannin hydrolysis, are natural antioxidants, which have been widely used in food preservation, with strong effect and low toxicity. Tannin with larger molecular weight has stronger antioxidant capacity than the former two. Its oxidation resistance is reflected in: on the one hand, reducing the oxygen content in the environment through reduction reaction, on the other hand, releasing hydrogen as a hydrogen donor to combine with free radicals in the environment, preventing the chain reaction initiated by free radicals, thus preventing the continuation of oxidation. Tannin, vc and vE have synergistic antioxidant effects. It is considered that tannins integrate metal ions that passivate and promote oxidation, or tannins can regenerate with vc and VE. Excessive free radicals in organisms can damage biological macromolecules, affect meningeal flow and destroy protein conformation, thus inducing aging of tissues and organs, promoting the aging process and leading to many diseases. The research shows that tannin has a broad-spectrum scavenging ability to superoxide radical (0L, HQ') and free radical (0U, nitroxyl (NQ'), singlet oxygen (OH'), oxygen (ob) and hydrogen peroxide (H202) and other active oxygen and lipid peroxide radicals (Roo, R,). C Nda 5a 1 is stronger than common antioxidants such as Vc and VE. The scavenging ability of several components in tea to lipid peroxide residue in aqueous solution was determined by electron spin gillshaker. The results show that the greater the polymerization degree of ECG, EGCG, ECC, gallic acid, epicatechin, catechin and tannin, the more warp yarns, the stronger the inhibition effect on free radicals. 0Lu These LL2Js studied X kinds of tannins and related compounds with AOP/VC or AOP/NADPH inducing the formation of rat mitochondrial ribs as an index, and found that 23 of them had different degrees of antioxidant effects. Most of tannins 5m JIll can significantly inhibit the rise of ribs, and the IDb9 is less than VE, among which the hydrolytic type is stronger than the condensed type, and its activity depends on the position and number of meridian bases. In addition, the experiment confirmed that tannin can activate the deletion of superoxide dismutase, which is caused by the change of enzyme configuration. As we all know, cangue has a strong ability to scavenge free radicals. Tannins in Mulberry, Carapax Trionycis and Eucommia ulmoides Oliv. It can reduce mitochondrial free radicals in liver, thus inhibiting lipid peroxidation in liver and protecting liver and kidney. It should be noted that hydrolyzed tannins have certain toxicity. Tannin can also prevent skin erythema and other damage caused by ultraviolet radiation, and increase skin elasticity and smoothness.
2.2.4 The important factors to prevent the occurrence and development of cardiovascular and cerebrovascular diseases are the increase of blood lipid concentration, the decrease of hemorheology and abnormal platelet function. Herbs containing tannins can improve this, so they are called "promoting blood circulation to steal". For example, grape seed can significantly reduce the complex of serum MLc tannin with extracellular or extracellular CB2 in rats fed with high cholesterol diet, and can antagonize calcium-induced contraction of smooth muscle and myocardium, thus lowering blood pressure. Tannin in beetles can reduce the blood pressure of hypertensive rats by oral intravenous injection, but it does not affect the blood pressure of normal rats L 15J. Persimmon tannins and rhubarb tannins have no antihypertensive effect, but can reduce the possibility of cerebral hemorrhage and cerebral infarction.
2.2.5 Anti-tumor and immunity enhancement Some people think that tannins are carcinogenic. For example, beetles (containing 1 1%-26% tannin) are related to the high incidence of oral cancer and esophageal cancer in the Far East. Residents in the Caribbean often drink herbal tea wells and take sorghum as their staple food, but the incidence of esophageal cancer is high. However, more studies and investigations support the anti-cancer effect of tannin. In fact, except aflatoxin, the probability that carcinogens in food or herbal products actually cause cancer is very low Lni. Drinking green tea and eating fruits and vegetables for a long time can effectively reduce the incidence of cancer and tumor, which is related to tannin. Mice were injected with tannins and related compounds intraperitoneally and cultured in injected sarcoma-180 cells. It was found that hydrolyzed tannins, especially lotus tannins, greatly prolonged their life. Tannin can inhibit the mutation and development stage of tumor formation, and has multiple inhibitory activities on various mutagens (ultraviolet rays, chemicals, etc.). ) and can promote the repair of biological macromolecules and cells. The molecular weight of tannin, the content of diacyl and the spatial conformation of phenolic group are the necessary factors for anticancer activity. Miymbl% I analyzed the relationship between tannin structure and anti-tumor, and found that the structure with the most diacyl groups had the strongest activity. It is speculated that the anti-tumor effect of tannin is achieved by improving the immunity of recipient animals to tumor cells.
Summary More and more studies show that tannin is widely used in chemical industry, medicine, food and other fields. As far as food industry is concerned, tannin has many physiological activities on human body, which is worth further development and utilization. In the food industry, it can be used as functional ingredients to make health food, produce food additives, flavor food additives and flavor agents, and pay attention to the adjustment of diet, such as eating less food with high tannin content, drinking tea in moderation, not drinking strong tea after meals, and separating tannin drugs from three meals. As long as it is used reasonably, it will certainly make the gift of nature serve mankind better.
tannic acid
Alias tannin, tannin, tannic acid, tannic acid
Tannic acid in mbth
indicate
This product can precipitate protein, has astringent effect, and can harden skin, thus protecting mucosa, preventing excessive secretion and stopping bleeding; It can relieve local pain, reduce plasma exudation from the injured part and prevent bacterial infection. Mainly used for neonatal bedsore, eczema, hemorrhoids and diaper rash.
Usage and dosage: for external use, 2-3 times a day.
counteraction
When this product is used in a large area, it can be absorbed by the wound and cause poisoning, which has serious toxicity to the liver. Severe cases lead to liver necrosis, wound deepening and delayed healing, so it is not suitable for large-scale or long-term use.
Drug Interaction This product is incompatible with heavy metals and protein, so avoid contact with iron.
Specification ointment 10%, 20%.