What are the main active ingredients in tea like green tea extract and its benefits?

- Sep 23, 2019-

The active ingredients and pharmacological effects of tea (such as green tea, black tea, white tea, etc.), including catechins, methylated catechins, epigallocatechin-3,5-digallate, theaflavins, tea Red pigment, polyester catechin, oolong tea polyphenol, tea brown pigment, theanine, γ-aminobutyric acid, caffeine, flavonol and its glycosides, proanthocyanidins and anthocyanins.


◆ Catechins

1. Catechins

The catechin is the most important active ingredient in non-fermented tea such as green tea, white tea, yellow tea, oolong tea or tea with less fermentability, and the content generally accounts for 12% to 24% of the dry weight of the tea. There are more than 20 kinds of teas that have been found, the highest of which is EGCG (epigal catechin gallate), followed by EGC (epigal catechin), EC (epicate catechin) and ECG (table) Catechin gallate). EGCG is a tea-specific catechin. It is an ester of 2-linked phenol benzopyran with gallic acid. It has the commonality of phenolic antioxidants and has 6 ortho-phenolic hydroxyl groups in its structure. Better than many other properties of catechins. Many studies have shown that EGCG has the strongest antioxidant activity, scavenging free radicals, resisting free radical DNA damage, resisting radiation and ultraviolet rays, preventing lipid peroxidation, and lowering the content of low-density cholesterol, ultra-low-density cholesterol and triglycerides in serum. Signals that interfere with the survival of cancer cells, together with enzymes or antioxidants in the intestines, liver and lungs, prevent the vitality of certain carcinogens, resist the effects of pollution, sun and smoking, prevent skin aging and wrinkles, etc. Efficacy Currently, there are five main ways to prevent EGCG from fighting tumors:

(1) inhibiting the proliferation of cancer cells.

(2) Inducing apoptosis of cancer cells.

(3) inhibiting the activity of certain tumor-associated enzymes.

(4) Improve the cytotoxic sensitization of certain cells.

(5) Inhibition of certain cancer-promoting substances.


2. Methylted catechins

Methylated catechins are newly discovered catechins in recent years, mainly including EGCG3′′Me, EGCG4′′Me, ECG3′′Me, ECG4′′Me, etc. The chemical structural formula is shown in Figure 1.

Methylted catechins

Existing studies have shown that since methylated catechins contain methyl groups, the entire methylated catechin molecule is in a state of increased fat solubility. Therefore, the human body has higher digestion and absorption than normal catechins, such as EGCG3. "Me's oral absorption rate is 9 times higher than EGCG; and its stability in animal blood is significantly higher than EGCG. Therefore, methylated catechins show stronger pharmacology than EGCG in anti-allergic, anti-inflammatory and other aspects. Recently, methylated catechins EGCG3"Me and EGCG4"Me have been found to have anti-oxidation, protect liver cells, and lower blood pressure.

3. Epigallocatechin-3,5-digallate,EGCGG

Epigallocatechin-3,5-bisgallate is a catechin with 2 gallates, the chemical structure of which is shown in Figure 2. It exists only in the fresh leaves of some tea varieties, such as Benihomare in Japan, Assam in India, and cultivated species in Guangdong, Fujian Baxian tea. The content in the cultivar in Guangdong is 0.33% to 6.62%. The pharmacological action of EGCGG is mainly a strong inhibitory effect on pancreatic lipase. The IC50 (semi-inhibitory concentration) is 0.098 μmol, and the inhibitory effect is better than EGCG. Therefore, this component has a good weight-loss effect.

 Chemical structure of methylated catechin

◆ Catechin polymers

1. Theaflavins, TFs

Theaflavins are the main components of black tea. It was first discovered by Roberts in 1957. It is a kind of oxidized polyphenols in tea. It is soluble in ethyl acetate and has benzoic acid. A general term for catechin polymers of the phenolic ketone structure. The content of theaflavins generally accounts for 1% to 5% of the dry matter of black tea, which plays a decisive role in the color, aroma, taste and quality of black tea. It is the main component of the "light" of black tea soup, and is also important for the intensity and freshness of black tea. The ingredients are also the main substances that form the "golden circle" of black tea tea soup. Studies have shown that theaflavins are composed of dimers formed by oxidative polymerization of paired catechins. There are 13 kinds of theaflavin monomers identified so far, the most important of which are four: theaflavins (TF), Theaflavin-3-gallate (TF-3-G), theaflavin-3'-gallate (TF-3'-G) and theaflavin digallate (TF-3, 3'-DG) ). There are many reports on the pharmacological use of theaflavins. The main ones are: anti-oxidation, anti-cancer, anti-inflammatory, prevention of cardiovascular diseases, obesity and metabolic syndrome, neurodegenerative diseases such as Parkinson's syndrome and Alzheimer's. Symptoms, etc.

Formation pathway of TSs, TFs and TRs

2. Thearubigins, TRs

The safflower is the highest content of phenolic compounds in black tea, accounting for 6% to 15% of the dry matter of black tea. It is the main substance that constitutes the color of black tea. It plays a role in the taste and color of tea, as well as on human health. Extremely important role. Thearubigin is a complex formed by oxidative polymerization of one or several catechins or theaflavins in different processes during the fermentation of black tea. It contains both catechin enzymatic oxidative polymerization (condensation) reaction products and catechins. The non-enzymatic reaction products produced by the oxidation products and polysaccharides, proteins, nucleic acids and proanthocyanidins are extremely complicated in chemical composition and have not yet been clearly identified. At present, tandem LC-MS confirmed that at least 29 kinds of hydroxylated theaflavins, 12 kinds of theaflavin mono-gallates, and 9 kinds of theaflavin digallates (theaflavindi-) Gallates) and 10 theacitrin mono-gallates, and in each of the above homologous series, there are at least 10 parent compounds and hydroxylated derivatives in the form of mono or diterpenes. Studies have shown that thearubigin and theaflavins have similar effects on the inhibition of DNA-based transferase, and also have pharmacological effects such as anti-cancer, anti-oxidation, anti-inflammatory and antibacterial.


3. Theasinensins, TSs

Polyester catechin is formed by enzymatic or non-enzymatic oxidation of polyphenols mainly composed of catechins during tea making. It is detected in fresh tea leaves, green tea, black tea and oolong tea. . Studies have shown that TSs can be quickly absorbed by intestinal epithelial cells, and the absorption rate is significantly greater than catechin monomer (EGCG); TSs have the same or higher iron and antioxidant functions as EGCG, and are more easily absorbed and It can last for a long time in the blood. At present, the pharmacological effects of TSs are mainly found in the following aspects.

(1) Antioxidant effect

For example, the antioxidant properties (AOA) of TSs is not lower than EGCG; the resistance of TSA to lipid oxidation is not much different from that of EGCG, and the difference in antioxidant capacity between TSA, TSB, TSC, TSD and TSE is small.

(2) Anti-tumor effect

For example, TSs can induce apoptosis of HL-60 cells, inhibit the growth of human hepatoma cells, and significantly inhibit mouse xenografts.

(3) Enhance immunity

For example, TSs have enhanced cellular and humoral immunity in normal and immunocompromised mice.

(4) Anti-inflammatory, antiseptic, anti-viral effects

For example, TSA can regulate related chemokines (a class of cytokines with chemotactic activity, which play an important role in inflammatory reactions), such as interleukins and interferons exert their anti-inflammatory effects; TSA has bactericidal ability and adjuvant antibiotics ability.

(5) lowering blood sugar, lowering cholesterol, and losing weight

For example, TSA can significantly accelerate the excretion of neutral steroids in the feces, thereby reducing the steroid content in mice; TSs can inhibit the activity of α-glucosidase, preventing the breakdown of dietary fat into triglycerides in the blood. Triglyceride levels are elevated, while TSs also inhibit the absorption of carbohydrates, such as sugars.


4. Oolong tea polymerized polyphenols and oolong bis-alkanol dimers A and B

During the processing of oolong tea, polyphenolic compounds are polymerized into high molecular weight compounds under the action of polyphenol oxidase and heat, called oolong tea polyphenols (OTPP). OTPP is a characteristic compound of oolong tea, which can reach 114 mg/g in oolong tea. The study found that OTPP can inhibit post-prandial hypertriglyceridemia in mice, suggesting that oolong tea has a good weight loss effect.


5. Theabrownins, TBs

Tea brown pigment is one of the important biologically active ingredients in Pu'er tea. Many studies have suggested that the efficacy of Pu'er tea in reducing fat and reducing blood sugar is related to this ingredient. The content of the tea brown pigment in Pu'er tea ranges from 10% to 14%, and the average content is 12%. The tea brown pigment is not only the key factor determining the unique soup color and taste of Pu'er tea, but also the key factor for measuring the quality of Pu'er tea. The content of the three tea pigments of theaflavins, theaflavins and the theaflavins in Pu'er tea is 0.16% to 0.29%, 0 to 0.99% and 8.33% to 13.65%, respectively.


◆ Amino acids

1. L-Theanine

Theanine, also known as L-glutamic acid γ-ethylamide, is a free amino acid unique to tea. Theanine is easily soluble in water and has a sweet taste and a refreshing taste. Theanine is the highest free amino acid in tea, generally accounting for 0.5% to 3.0% of the weight of dry tea. Theanine is chemically similar to the active substances in the brain, such as glutamine and glutamic acid. Studies have shown that L-theanine can easily cross the blood-brain barrier and act in the brain, protecting against ischemic brain damage and glutamate-induced neuronal cell death. In addition, it has also found that theanine relieves stress, promotes sleep, anti-anxiety, anti-depression, improves learning ability and memory, and prevents neurosis such as Alzheimer's disease (AD), Parkinson's syndrome (PD), and stroke. There are good pharmacological effects in degenerative diseases.

2. γ-aminobutyric acid (GABA)

Gamma-aminobutyric acid, also known as 4-aminobutyric acid, is another interesting non-protein amino acid in tea. GABA is an important inhibitory neurotransmitter that is deeply studied in the present. It participates in various metabolic activities of the human body and has strong physiological activity. GABA can calm nerves, resist anxiety, lower blood pressure, promote ethanol metabolism, and treat neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's syndrome (PD) and stroke. The latest research shows that GABA also has functions such as preventing skin aging, eliminating body odor, improving lipid metabolism, preventing arteriosclerosis, and effectively losing weight.


◆ Caffeine

Tea tree is the highest content of caffeine in nature. The content of caffeine in tea leaves is generally 2% to 4% (up to 5.5%), higher than that of coffee beans (1% to 2%) and cocoa beans (0.3% to 2.0%). , cola fruit (1% to 2%), etc. Caffeine is the most important substance in the tea soup. The pharmacological action of caffeine is mainly to stimulate the central nervous system, improve thinking efficiency, diuretic and so on. The latest research found that caffeine has a variety of synergistic effects, such as in the weight loss and inhibition of kidney cancer, skin cancer test, the combination of caffeine and catechin is better than catechin and caffeine alone; in human trials, caffeine In combination with theanine, it can change the content of GABA, serotonin and dopamine in the brain, increase the alpha wave activity of the brain, and achieve a relaxed state; a mixture of caffeine (150 mg) and L-theanine (250 mg) Can make people more agile, digital memory response time is shorter, sentence expression is more accurate; in the hit rate and target experiments, the mixture of caffeine (50 mg) and L-theanine (100 mg) is compared with placebo and single group Points can significantly improve attention; in the cognitive ability test, a mixture of L-theanine (97 mg) and caffeine (40 mg) can significantly improve the attention of the task switching.


5. Flavonols and their glycosides

Flavonols and its glycosides are a class of active ingredients that have attracted much attention in recent years. Most of the flavonols in tea are in the form of glycosides, which are the main body of water-soluble yellow pigment in tea soup, accounting for 3% to 4% of the dry weight of tea. The flavonol glycosides in tea mainly include three types of monoglycosides, disaccharides and trisaccharides, and the glycosyl groups thereof include glucose, rhamnose, galactose, and sucrose. Flavonols and their glycosides have many pharmacological effects such as anti-inflammatory, antibacterial, hypoglycemic, anti-oxidative, anti-radiation, anti-cancer, anti-tumor, anti-AIDS, and enhance immunity. They are important antioxidants and are very clinically useful. Wide range, can prevent cardiovascular and respiratory diseases. Nowadays, there are some new ideas that flavonoids and their glycosides can also act as cell signaling substances to regulate the normal physiological functions of the human body.


6. Proanthocyanidins and anthocyanins

Proanthocyanidins are natural antioxidants commonly found in plants. They are made up of different amounts of catechins or epicatechins. The simplest proanthocyanidins are dimers formed by catechins or epicatechins, in addition to trimers, tetramers, etc. up to the decamer. The dimer to pentamer is generally referred to as an oligomer (abbreviated as OPC) and the pentamer or higher is referred to as a polymer (PPC). Generally oligomers higher polymers have greater resistance to oxidation and scavenging free radicals. To date, more than 20 proanthocyanidins have been found in fresh tea leaves and green tea, and their content in green tea can reach 2% to 3% of dry weight. There are currently 20 anthocyanins identified, and 6 species are common in plants, namely geranium pigment (Pg), cyanidin (Cy), delphinidin (Dp), peony pigment (Pn), Bovine pigment (Pt) and mallow (Mv). The most important physiological function of anthocyanins is their ability to resist oxidation and free radical scavenging. Studies have shown that anthocyanins are the most effective antioxidants found in humans today and the most potent free radical scavengers. The antioxidant properties of anthocyanins are 50 times higher than VE and 20 times higher than VC. In addition, anthocyanins also have a variety of pharmacological functions such as anti-mutation, protection of vision, prevention of diabetes and cardiovascular disease.

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