Green Tea Extract

Green tea extract Uses and synthesis methods
Plant extracts
Green tea extract is a product extracted from green tea (Canellia Sinensis). Commercial extracts are usually standardized to contain 60% tea polyphenols. It has antioxidant, anti-aging, anti-cancer and anti-mutation effects, prevention of atherosclerosis, cardiovascular disease, hypertension and other diseases; killing harmful bacteria in the body, anti-virus, prevention of diabetes, and prevention of dental caries. This information is edited and compiled by Shi Yan of Chemicalbook.
Chemical composition
Tea polyphenols are extracts of tea leaves, and the composition of tea leaves is very complex. More than 600 compounds have been found in tea extracts.
Polyphenols:
Including flavanols (catechins), 4-hydroxyflavanols, flavonoids, anthocyanins and phenolic acids. Flavanols are the main body of polyphenols, accounting for about 80%, including catechin (C), epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG) and a small amount of catechin gallate (CG), gallocatechin (GC), etc. Flavonoids include quercetin, kaempferol, flavonol gallate, etc. Anthocyanidins: Anthocyanidins, chlorophyll, lutein and carotene, etc. Alkaloids: Mainly caffeine (Caffeine, 1% to 5%) and a small amount of theophylline, theobromine and xanthine. Triterpenes: Theasapogenol E, theafolisaponin, etc. Protein and amino acids:
Theanine, phenylalanine, glutamic acid, etc., as well as hydrolases, proteases, phosphorylases, oxidoreductases, etc.
Carbohydrates:
Cellulose, starch, pectin, etc.
Aromatic substances:
Heptenol, heptenal, herb alcohol, benzyl alcohol, etc.
Source
The earliest use of tea was in the 28th century BC, and there were documents in the 3rd century BC. China has records of using tea to treat diseases since ancient times, such as "Shennong Food Classic" and "Compendium of Materia Medica". Tea is approved as a traditional diuretic in Belgium, allowed as an oral agent in France, listed in the food and natural products category in Sweden, and used as a dietary supplement in the United States. Tea originated in Yunnan, my country. my country's tea-growing areas are located in temperate and subtropical areas, from Taiwan at 122° east longitude in the east to Longchuan area of ​​Yunnan at 98° east longitude in the west, from Hainan Island at 18° north latitude in the south, and to Penglai Mountain in Shandong near 38° north latitude in the north. Tea is mainly distributed in Hunan, Zhejiang, Anhui, Sichuan, Yunnan, Hubei, Guangdong, Guizhou, Fujian, Jiangsu, Shaanxi, Henan, Shandong and other places. The world produces about 25 million tons of tea every year. India and China are the world's largest tea producers. Green tea is the main tea, accounting for about 80%.

Preparation method
1. GTC-30 (R) production process
(1) Production process
Green tea is extracted with pure water, the extract is cooled, filtered, concentrated under reduced pressure, and spray dried.
This process is suitable for the production of GTC-30 (R), with a yield of about 20%.
(2) Selection test of extraction conditions
Water consumption for extraction: 90-95℃, extraction time is 20 minutes, the extraction rate of 12 times the amount of water is 67% (4E), and 77% when the amount is 18 times, that is, the extraction rate increases with the increase of water.
Extraction time: Under 90-95℃, the extraction time of 18 times the amount of water is 30 minutes, and its extraction rate decreases (compared to 20 minutes). This may be due to the fact that catechins are easily oxidized due to excessive heating time.
Extraction times: 18 times the amount of water for two extractions, namely 12 times the amount of water (20min) and 6 times (15min), the second extraction rate can reach 29%, and the total extraction rate can reach 96%.
Considering the unstable factors such as polyphenols being easily oxidized and mutarotated under high temperature conditions, 18 times the amount of water and 90-95℃ are used for one extraction for 20 minutes. The longer the water extract stays at high temperature, the greater the possibility that EGCG will mutarotate to GCG. The GCG extraction rate is as high as about 350% when the water extract is extracted at 90-95℃ for 20 minutes, and it can reach about 450% at 30 minutes. In addition, 30% ethanol extraction has the advantages of low temperature, low solvent usage, and high extraction rate, and the GCG extraction rate is only 95%, which is only 25%-30% of the same time at 90-95℃.
2. GTC-30 (S) production process
Green tea is extracted with pure water, the extract is cooled, filtered, decaffeinated, concentrated under reduced pressure, and spray dried.
This process is suitable for the production of GTC-30 (S), with a yield of about 20%.
3. GTC-60 (S) production process
(1) Production process
Green tea is extracted with pure water, the extract is cooled, filtered, decaffeinated, extracted with ethyl acetate, ethyl acetate is recovered, and spray dried.
This process is suitable for the production of GTC-60 (S) with a yield of 5%.
(2) Decaffeination test
Acid-base extraction test: Take the green tea water extract and conduct the test according to the test method in Figure 2. Under the same conditions, reduce pressure and concentrate, vacuum dry, and determine the content of 4E (EC, ECG, EGC, EGCG) and c.f. (caffeine).
Under acidic conditions (pH 2-3), it is not only conducive to the extraction and transfer of catechins, but also conducive to the separation of the two phases. In addition, extraction under acidic conditions can reduce the transfer of caffeine to the organic phase and reduce the caffeine content in the product. The comparison of the pH value adjustment experiment with citric acid, hydrochloric acid, acetic acid and phosphoric acid shows that after adjusting the pH value to 2-3 with phosphoric acid and leaving it for about 15 hours, it has the advantages of high catechin extraction rate, low caffeine content and relatively high yield.

Figure 2 shows the extraction test results

Figure 3 shows the comparison of four methods for removing caffeine

The existing domestic patent literature mostly uses chlorine-containing solvents such as chloroform and dichloromethane to remove caffeine, which is not conducive to industrial production. By adjusting the pH of the aqueous phase (pH about 2-3) and then extracting, and washing the organic phase with water many times, the caffeine content in the product can be reduced to less than 1%, but at the same time as removing caffeine, the EGC (on the HPLC chromatogram, EGC and Caffeine are close in position) accounting for about 20% of the total 4E content is basically lost, which greatly increases the cost of GTP-60 (S). The ion exchange resin method is a better method for removing caffeine.
Analytical method
1. Thin layer chromatography
Sample solution preparation: Take 0.1g of green tea extract, add 10ml of methanol to dissolve, filter, and use the filtrate for spotting.
Chromatographic conditions: Plate: 0.5% CMC-Na silica gel G plate, activated at 105℃ for 30 minutes; developer: chloroform-methanol-formic acid (8:2:0.1); development distance: 16cm; color developer: 0.05% p-dimethylaminobenzaldehyde ethanol solution containing 1% hydrochloric acid.
Result: Catechin spots appear purple.
2. Determination of tea polyphenols in green tea extract by ferric tartrate method
(1) Preparation of chemical reagents
Ferrous tartrate solution: weigh 1g (accurate to 0.0001g) ferrous sulfate (FeSO4.7H2O) and 5g potassium sodium tartrate (KnaC4H4O6.4H2O) (accurate to 0.0001g), dissolve in water and make up to 1000ml.
pH7.5 phosphate buffer: weigh 11.876g disodium hydrogen phosphate (Na2HPO4·2H2O), dissolve in water and make up to 1000ml; weigh 9.078g potassium dihydrogen phosphate (KH2PO4) baked in a 110℃ oven, dissolve in water and make up to 1000ml; mix the two solutions evenly at 85:15 (V/V) to obtain a pH7.5 buffer solution.
(2) Determination method: Accurately weigh 200 mg of this product, place it in a 100 ml volumetric flask, add heavy distilled water, shake to dissolve, dilute to scale, and shake well. Take 1 ml of the extract, place it in a 25 ml volumetric flask, add 4 ml of heavy distilled water and 5 ml of ferric tartaric acid solution, dilute to scale with pH 7.5 phosphate buffer, and shake well. Using the reagent blank solution as a control, measure the absorbance at a wavelength of 540 nm. The content of tea polyphenols is calculated as follows: Tea polyphenols%=1.957AV1/0.50×1000MV2×100
A: absorbance of the test solution; V1: the amount of the test sample extract (100 ml); V2: the amount of liquid used in the determination (1 ml); M: the amount of the test sample (g);
1.957: When the absorbance is equal to 0.50, 1 ml of the test sample extract contains 1.957 mg of tea polyphenols. Some also use a modified coefficient of 1.44.
Note: This method is suitable for products with a tea polyphenol content of ≤50.0%. It is recommended for green tea extracts with EGCG/ECG (content) greater than 4, that is, for the content determination of pure small-leaf green tea extracts.
Clinical efficacy
Tea is bitter, sweet, and cool. It can clear the head, eliminate thirst, resolve phlegm, help digestion, promote diuresis, and detoxify. It can treat headaches, blurred vision, drowsiness, irritability, thirst, food stagnation, phlegm stagnation, and dysentery.
Green tea extract has a wide range of biological activities, including anti-oxidation, anti-aging, anti-cancer and anti-mutation, prevention of atherosclerosis, cardiovascular disease, hypertension, etc.; it can kill harmful bacteria in the body, resist viruses, prevent diabetes, and prevent dental caries.
Application Overview
Green tea extract is widely used in medicine and health care. Pharmaceutical preparations for cardiovascular and cerebrovascular diseases include tea polyphenol capsules, tea juice tablets (made from boiling water extract of green tea) for leukopenia, and tea polyphenol lozenges for throat inflammation. In health care, there are various health teas such as TV tea and slimming tea to prevent TV radiation. In cosmetics, there are tea polyphenol sunscreen, tea polyphenol skin cream, tea polyphenol refreshing shower gel, tea deodorant, anti-caries medicinal toothpaste, etc. In foreign countries, green tea extract has been used to make various single and compound preparations of different specifications, such as liquid tea bags produced by Arkopharma in France, which are used as appetite suppressants for weight loss.
Pharmacological effects
1. Antioxidant effect
Tea polyphenols can directly remove active oxygen free radicals. The structure of tea polyphenols is rich in phenolic hydroxyl groups, which can provide active hydrogen to inactivate free radicals. The free radicals formed by oxidation have high stability due to the catechol structure. Therefore, tea polyphenols are hydrogen-supplying free radical inhibitors. Tea polyphenols have the functions of inhibiting lipid peroxidation, chelating metal ions, and activating the intracellular antioxidant defense system.
2. Anti-cancer and anti-mutation effects
Green tea extract (GTE) has an inhibitory effect on a variety of animal tumors induced by carcinogens, including skin, lung, stomach, esophagus, colon, duodenum and other tumors. Its mechanism is very complex, mainly including: inhibiting the proliferation of cancer cells; blocking the generation of carcinogens; antioxidant effect; anti-mutation effect; anti-cancer effect; effect on the immune system, etc. Tea polyphenol compounds are effective ingredients for anti-cancer and anti-mutation, especially CG and ECG are the most important active components.
3. Sterilization and antibacterial, improving intestinal microbial structure
Tea catechin compounds have a bactericidal and inhibitory effect on many types of bacteria that are harmful to humans, such as Staphylococcus aureus, Vibrio cholerae, and Escherichia coli. Tea polyphenols have the effect of promoting the growth and proliferation of many beneficial bacteria in the human intestine, such as bifidobacteria, and these bacteria can not only produce many nutrients (such as B vitamins) in the intestine, but also inhibit the proliferation of harmful bacteria.
4. Antiviral effect
Tea catechins have an inhibitory effect on influenza viruses A and B; EGCG and ECG have a strong inhibitory effect on HIV even at a low concentration of 0.01-0.02 mg/ml.
5. Lipid-lowering and weight-loss, prevention and treatment of atherosclerosis
Tea catechins, especially EGCG, can inhibit the synthesis of cholesterol in cells, and have the effect of lowering LDL cholesterol and increasing HDL cholesterol in the blood. The former has the effect of promoting human atherosclerosis, while the latter has the effect of preventing and improving atherosclerosis.
6. Antihypertensive effect
Tea catechins, especially ECG and EGCG, have a significant inhibitory effect on angiotensin I converting enzyme.
7. Tooth-healthy and anti-caries effect
Research in the late 1980s found that polyphenol compounds in tea are the most important effective substances for tea's anti-caries effect.
8. Other effects
Hypoglycemic effect, anti-radiation effect, anti-allergic effect, immune enhancement, and anti-aging.