Epigallocatechin gallate

Last updated
Epigallocatechin gallate
Epigallocatechin gallate structure.svg
Epigallocatechin gallate 3D spacefill.png
Names
IUPAC name
(2R,3R)-3′,4′,5,5′,7-Pentahydroxyflavan-3-yl 3,4,5-trihydroxybenzoate
Preferred IUPAC name
(2R,3R)-5,7-Dihydroxy-2-(3,4,5-trihydroxyphenyl)-3,4-dihydro-2H-1-benzopyran-3-yl 3,4,5-trihydroxybenzoate
Other names
(-)-Epigallocatechin gallate
(2R,3R)-3′,4′,5,5′,7-pentahydroxyflavan-3-yl gallate
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.111.017 OOjs UI icon edit-ltr-progressive.svg
KEGG
MeSH Epigallocatechin+gallate
PubChem CID
UNII
  • InChI=1S/C22H18O11/c23-10-5-12(24)11-7-18(33-22(31)9-3-15(27)20(30)16(28)4-9)21(32-17(11)6-10)8-1-13(25)19(29)14(26)2-8/h1-6,18,21,23-30H,7H2/t18-,21-/m1/s1 Yes check.svgY
    Key: WMBWREPUVVBILR-WIYYLYMNSA-N Yes check.svgY
  • InChI=1/C22H18O11/c23-10-5-12(24)11-7-18(33-22(31)9-3-15(27)20(30)16(28)4-9)21(32-17(11)6-10)8-1-13(25)19(29)14(26)2-8/h1-6,18,21,23-30H,7H2/t18-,21-/m1/s1
    Key: WMBWREPUVVBILR-WIYYLYMNBM
  • O=C(O[C@@H]2Cc3c(O[C@@H]2c1cc(O)c(O)c(O)c1)cc(O)cc3O)c4cc(O)c(O)c(O)c4
Properties
C22H18O11
Molar mass 458.372 g/mol
soluble (5 g/L)[ vague ] [1]
Solubility soluble in ethanol, DMSO, dimethyl formamide [1] at about 20 g/L [2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
X mark.svgN  verify  (what is  Yes check.svgYX mark.svgN ?)

Epigallocatechin gallate (EGCG), also known as epigallocatechin-3-gallate, is the ester of epigallocatechin and gallic acid, and is a type of catechin.

Contents

EGCG – the most abundant catechin in tea – is a polyphenol under basic research for its potential to affect human health and disease. EGCG is used in many dietary supplements.

Food sources

Tea

It is found in high content in the dried leaves of green tea (7380 mg per 100 g), white tea (4245 mg per 100 g), and in smaller quantities, black tea (936 mg per 100 g). [3] During black tea production, the catechins are mostly converted to theaflavins and thearubigins via polyphenol oxidases.[ which? ] [4]

Other

Trace amounts are found in apple skin, plums, onions, hazelnuts, pecans, and carob powder (at 109 mg per 100 g). [3]

Bioavailability

When taken orally, EGCG has poor absorption even at daily intake equivalent to 8–16 cups of green tea, an amount causing adverse effects such as nausea or heartburn. [5] After consumption, EGCG blood levels peak within 1.7 hours. [6] The absorbed plasma half-life is ~5 hours, [6] but with majority of unchanged EGCG excreted into urine over 0 to 8 hours. [6] Methylated metabolites appear to have longer half-lives and occur at 8–25 times the plasma levels of unmetabolized EGCG. [7]

Research

Well-studied in basic research, EGCG has various biological effects in laboratory studies. [8] [9] [10] [11]

A 2011 analysis by the European Food Safety Authority found that a cause and effect relationship could not be shown for a link between tea catechins and the maintenance of normal blood LDL-cholesterol concentration. [12] A 2016 review found that high daily doses (107 to 856 mg/day) taken by human subjects over four to 14 weeks produced a small reduction of LDL cholesterol. [13]

Potential toxicity

A 2018 review showed that excessive intake of EGCG may cause liver toxicity. [14] In 2018, the European Food Safety Authority stated that daily intake of 800 mg or more could increase risk of liver damage. [15]

Taken as a capsule or tablet 338  mg per day of EGCG is considered safe, whereas 704 mg per day is safe if consumed as a tea beverage. [14] 100  mL of green tea contains about 70.2 mg of EGCG (about 165 mg per cup). [15]

Regulation

Over 2008 to 2017, the US Food and Drug Administration issued several warning letters to manufacturers of dietary supplements containing EGCG for violations of the Federal Food, Drug, and Cosmetic Act. Most of these letters informed the companies that their promotional materials promoted EGCG-based dietary supplements in the treatment or prevention of diseases or conditions that cause them to be classified as drugs under the United States code, [16] [17] [18] while another focused on inadequate quality assurance procedures and labeling violations. [19] The warnings were issued because the products had not been established as safe and effective for their marketed uses and were promoted as "new drugs", without approval as required under the Act. [18]

See also

Related Research Articles

<span class="mw-page-title-main">Niacin</span> Organic compound and a form of vitamin B3

Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variety of whole and processed foods, with highest contents in fortified packaged foods, meat, poultry, red fish such as tuna and salmon, lesser amounts in nuts, legumes and seeds. Niacin as a dietary supplement is used to treat pellagra, a disease caused by niacin deficiency. Signs and symptoms of pellagra include skin and mouth lesions, anemia, headaches, and tiredness. Many countries mandate its addition to wheat flour or other food grains, thereby reducing the risk of pellagra.

<span class="mw-page-title-main">Green tea</span> Unoxidized tea

Green tea is a type of tea that is made from Camellia sinensis leaves and buds that have not undergone the same withering and oxidation process which is used to make oolong teas and black teas. Green tea originated in China, and since then its production and manufacture has spread to other countries in East Asia.

<span class="mw-page-title-main">Gallic acid</span> 3,4,5-Trihydroxybenzoic acid

Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6H2(OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. It is a white solid, although samples are typically brown owing to partial oxidation. Salts and esters of gallic acid are termed "gallates".

<span class="mw-page-title-main">Flavonoid</span> Class of plant and fungus secondary metabolites

Flavonoids are a class of polyphenolic secondary metabolites found in plants, and thus commonly consumed in the diets of humans.

<span class="mw-page-title-main">Flavan-3-ol</span> Category of polyphenol compound

Flavan-3-ols are a subgroup of flavonoids. They are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2H-chromen-3-ol skeleton. Flavan-3-ols are structurally diverse and include a range of compounds, such as catechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, proanthocyanidins, theaflavins, thearubigins. They play a part in plant defense and are present in the majority of plants.

<span class="mw-page-title-main">Polyphenol</span> Class of chemical compounds

Polyphenols are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some of which have been used historically as dyes and for tanning garments.

<span class="mw-page-title-main">Nootropic</span> Drug, supplement, or other substance that improves cognitive function

Nootropics are numerous natural, semi-synthetic and synthetic molecules that improve cognitive functions.

Although health benefits have been assumed throughout the history of using Camellia sinensis as a common beverage, there is no high-quality evidence that consuming tea confers significant benefits other than possibly increasing alertness, an effect caused by caffeine in the tea leaves. In clinical research conducted over the early 21st century, tea has been studied extensively for its potential to lower the risk of human diseases, but there is no good scientific evidence to indicate that consuming tea affects any disease or improves health.

<span class="mw-page-title-main">Catechin</span> Type of natural phenol as a plant secondary metabolite

Catechin is a flavan-3-ol, a type of secondary metabolite providing antioxidant roles in plants. It belongs to the subgroup of polyphenols called flavonoids.

<span class="mw-page-title-main">Quercetin</span> Chemical compound

Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is found in many fruits, vegetables, leaves, seeds, and grains; capers, red onions, and kale are common foods containing appreciable amounts of it. It has a bitter flavor and is used as an ingredient in dietary supplements, beverages, and foods.

Polyphenon is a series of high grade green tea polyphenol extracts manufactured by the Mitsui Norin Co., Ltd. of Japan. The extracts are in part the result of a water based extraction method which begins with green tea leaves, and then involves successive steps which concentrate the catechins thought to be responsible for the health benefits of green tea.

<span class="mw-page-title-main">Hydroxytyrosol</span> Chemical compound

Hydroxytyrosol is an organic compound with the formula (HO)2C6H3CH2CH2OH. Classified as a phenylethanoid, i.e. a relative of phenethyl alcohol. Its derivatives are found in a variety of natural sources, notably olive oils and wines. Hydroxytyrosol is a colorless solid, although samples often turn beige during storage. It is a derivative, formally speaking, of catechol.

Thearubigins are polymeric polyphenols that are formed during the enzymatic oxidation and condensation of two gallocatechins with the participation of polyphenol oxidases during the fermentation reactions in black tea. Thearubigins are red in colour and are responsible for much of the staining effect of tea. Therefore, a black tea often appears red while a green or white tea has a much clearer appearance. The colour of a black tea, however, is affected by many other factors as well, such as the amount of theaflavins, another oxidized form of polyphenols.

<span class="mw-page-title-main">Gallocatechol</span> Chemical compound

Gallocatechol or gallocatechin (GC) is a flavan-3-ol, a type of chemical compound including catechin, with the gallate residue being in an isomeric trans position.

<span class="mw-page-title-main">Theaflavin digallate</span> Chemical compound

Theaflavin digallate (TFDG) is an antioxidant natural phenol found in black tea, and a theaflavin derivative.

<span class="mw-page-title-main">Phenolic content in wine</span> Wine chemistry

The phenolic content in wine refers to the phenolic compounds—natural phenol and polyphenols—in wine, which include a large group of several hundred chemical compounds that affect the taste, color and mouthfeel of wine. These compounds include phenolic acids, stilbenoids, flavonols, dihydroflavonols, anthocyanins, flavanol monomers (catechins) and flavanol polymers (proanthocyanidins). This large group of natural phenols can be broadly separated into two categories, flavonoids and non-flavonoids. Flavonoids include the anthocyanins and tannins which contribute to the color and mouthfeel of the wine. The non-flavonoids include the stilbenoids such as resveratrol and phenolic acids such as benzoic, caffeic and cinnamic acids.

<span class="mw-page-title-main">Prodelphinidin</span>

Prodelphinidin is a name for the polymeric tannins composed of gallocatechin. It yields delphinidin during depolymerisation under oxidative conditions.

<span class="mw-page-title-main">Gallocatechin gallate</span> Chemical compound

Gallocatechin gallate (GCG) is the ester of gallocatechin and gallic acid and a type of catechin. It is an epimer of epigallocatechin gallate (EGCG).

<span class="mw-page-title-main">Phenolic content in tea</span> Natural plant compounds

The phenolic content in tea refers to the phenols and polyphenols, natural plant compounds which are found in tea. These chemical compounds affect the flavor and mouthfeel of tea. Polyphenols in tea include catechins, theaflavins, tannins, and flavonoids.

References

  1. 1 2 "(-)-Epigallocatechin gallate". Chemicalland21.com.
  2. ↑ "Product Information: (-)-Epigallocatechin Gallate" (PDF). Cayman Chemical. 4 September 2014.
  3. 1 2 Bhagwat, Seema; Haytowitz, David B.; Holden, Joanne M. (September 2011). USDA Database for the Flavonoid Content of Selected Foods, Release 3 (PDF) (Report). Agricultural Research Service, U.S. Department of Agriculture. pp. 2, 98–103. Retrieved 18 May 2015.
  4. ↑ Lorenz, Mario; Urban, Janka; Engelhardt, Ulrich; Baumann, Gert; Stangl, Karl; Stangl, Verena (January 2009). "Green and Black Tea are Equally Potent Stimuli of NO Production and Vasodilation: New Insights into Tea Ingredients Involved". Basic Research in Cardiology. 104 (1): 100–10. doi:10.1007/s00395-008-0759-3. PMID   19101751. S2CID   20844066.
  5. ↑ Chow, H-H. Sherry; Cai, Yan; Hakim, Iman A.; Crowell, James A.; Shahi, Farah; Brooks, Chris A.; Dorr, Robert T.; Hara, Yukihiko; Alberts, David S. (15 August 2003). "Pharmacokinetics and safety of green tea polyphenols after multiple-dose administration of epigallocatechin gallate and polyphenon E in healthy individuals". Clinical Cancer Research. 9 (9): 3312–19. PMID   12960117.
  6. 1 2 3 Lee, Mao-Jung; Maliakal, Pius; Chen, Laishun; Meng, Xiaofeng; Bondoc, Flordeliza Y.; Prabhu, Saileta; Lambert, George; Mohr, Sandra; Yang, Chung S. (October 2002). "Pharmacokinetics of tea catechins after ingestion of green tea and (-)-epigallocatechin-3-gallate by humans: formation of different metabolites and individual variability". Cancer Epidemiology, Biomarkers & Prevention. 11 (10 Pt 1): 1025–32. PMID   12376503.
  7. ↑ Manach, C; Williamson, G; Morand, C; Scalbert, A; Rémésy, C (January 2005). "Bioavailability and bioefficacy of polyphenols in humans. I. Review of 97 bioavailability studies". The American Journal of Clinical Nutrition. 81 (1 Suppl): 230S–242S. doi: 10.1093/ajcn/81.1.230S . PMID   15640486.
  8. ↑ Fürst, Robert; Zündorf, Ilse (May 2014). "Plant-derived anti-inflammatory compounds: hopes and disappointments regarding the translation of preclinical knowledge into clinical progress". Mediators of Inflammation. 2014: 146832. doi: 10.1155/2014/146832 . PMC   4060065 . PMID   24987194. 146832.
  9. ↑ Granja, Andreia; Frias, Iúri; Neves, Ana Rute; Pinheiro, Marina; Reis, Salette (2017). "Therapeutic Potential of Epigallocatechin Gallate Nanodelivery Systems". BioMed Research International. 2017: 1–15. doi: 10.1155/2017/5813793 . ISSN   2314-6133. PMC   5534279 . PMID   28791306.
  10. ↑ Wu, Dayong; Wang, Junpeng; Pae, Munkyong; Meydani, Simin Nikbin (2012). "Green tea EGCG, T cells, and T cell-mediated autoimmune diseases". Molecular Aspects of Medicine. 33 (1): 107–18. doi:10.1016/j.mam.2011.10.001. ISSN   0098-2997. PMID   22020144.
  11. ↑ Riegsecker, Sharayah; Wiczynski, Dustin; Kaplan, Mariana J.; Ahmed, Salahuddin (2013). "Potential benefits of green tea polyphenol EGCG in the prevention and treatment of vascular inflammation in rheumatoid arthritis". Life Sciences. 93 (8): 307–12. doi:10.1016/j.lfs.2013.07.006. PMC   3768132 . PMID   23871988.
  12. ↑ EFSA NDA Panel (EFSA Panel on Dietetic Products, Nutrition and Allergies) (2011). "Scientific Opinion on the substantiation of health claims related to Camellia sinensis (L.) Kuntze (tea), including catechins in green tea, and improvement of endothelium-dependent vasodilation (ID 1106, 1310), maintenance of normal blood pressure". EFSA Journal. 9 (4): 2055. doi: 10.2903/j.efsa.2011.2055 .
  13. ↑ Momose Y; et al. (2016). "Systematic review of green tea epigallocatechin gallate in reducing low-density lipoprotein cholesterol levels of humans". Int J Food Sci Nutr. 67 (6): 606–13. doi:10.1080/09637486.2016.1196655. PMID   27324590. S2CID   39704366.
  14. 1 2 Hu, J; Webster, D; Cao, J; Shao, A (2018). "The safety of green tea and green tea extracts consumption in adults – Results of a systematic review". Regulatory Toxicology and Pharmacology. 95: 412–33. doi: 10.1016/j.yrtph.2018.03.019 . PMID   29580974.
  15. 1 2 Younes, Maged; Aggett, Peter; Aguilar, Fernando; et al. (18 April 2018). "Scientific opinion on the safety of green tea catechins". EFSA Journal. 16 (4): e05239. doi: 10.2903/j.efsa.2018.5239 . PMC   7009618 . PMID   32625874.
  16. ↑ "Sharp Labs Inc: Warning Letter". Inspections, Compliance, Enforcement, and Criminal Investigations. Food and Drug Administration. 9 July 2008. Archived from the original on 23 October 2016. Retrieved 15 September 2015.
  17. ↑ "Fleminger Inc.: Warning Letter". Inspections, Compliance, Enforcement, and Criminal Investigations. Food and Drug Administration. 22 February 2010. Archived from the original on 23 October 2016. Retrieved 6 January 2015.
  18. 1 2 "LifeVantage Corporation: Warning Letter". Inspections, Compliance, Enforcement, and Criminal Investigations. Food and Drug Administration. 17 April 2017. Retrieved 30 September 2017.
  19. ↑ "N.V.E. Pharmaceuticals, Inc.: Warning Letter". Inspections, Compliance, Enforcement, and Criminal Investigations. Food and Drug Administration. 22 July 2013. Retrieved 30 September 2017.
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