Catechin

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Epicatechin (EC)
Epigallocatechin (EGC)

Catechins are polyphenolic antioxidant plant metabolites. They belong to the family of flavonoids and, to be more specific, flavan-3-ols. These compounds are abundant in teas derived from the tea-plant Camellia sinensis as well as in some cocoas and chocolates (made from the seeds of Theobroma cacao).

The name of the catechin chemical family derives from catechu which is the juice or boiled extract of Mimosa catechu (Acacia catechu L.f))[1]

Contents

[edit] Catechin, epicatechin, gallocatechin, epigallocatechin, and the gallates

Catechin and epicatechin are epimers, with (-)-epicatechin and (+)-catechin being the most common optical isomers found in nature. Catechin was first isolated from the plant extract catechu, avove, from which it derives its name. Heating catechin past its point of decomposition releases pyrocatechol (also called catechol), which explains the common origin of the names of these compounds.

Epigallocatechin and gallocatechin contain an additional phenolic hydroxyl group when compared to epicatechin and catechin, respectively, similar to the difference in pyrogallol compared to pyrocatechol.

Catechin gallates are gallic acid esters of the catechins; such as EGCG (epigallocatechin gallate), which is commonly the most abundant catechin in tea.

[edit] Sources of catechins

Catechins constitute about 25% of the dry weight of fresh tea leaf[2], although total catechin content varies widely depending on clonal variation, growing location, seasonal/ light variation, and altitude. They are present in nearly all teas made from Camellia sinensis, including white tea, green tea, black tea and Oolong tea.

Catechins are also present in the human diet in chocolate[3], fruits, vegetables and wine[4] and are found in many other plant species[5].

Epigallocatechin gallate is the most abundant catechin in tea.

Another stereoisomer, (-)-catechin, is released from the roots of the invasive weed, spotted knapweed. It acts as an herbicide to inhibit competition by a wide range of other plant species. [6]. This phytotoxic compound inhibits seed germination and growth.

[edit] Health benefits of catechins

The health benefits of catechins have been studied extensively in humans and in animal models. Reduction in atherosclerotic plaques was seen in animal models.[7] Reduction in carcinogenesis was seen in vitro.[8]

Many studies on health benefits have been linked to the catechin content. According to Norman Hollenberg, professor of medicine at Harvard Medical School, epicatechin can reduce the risk of four of the major health problems: stroke, heart failure, cancer and diabetes. He studied the Kuna people in Panama, who drink up to 40 cups of cocoa a week, and found that the prevalence of the “big four” is less than 10%. He believes that epicatechin should be considered essential to the diet and thus classed as a vitamin.[9][10]

According to one researcher[11] epigallocatechin-3-gallate is an antioxidant that helps protect the skin from UV radiation-induced damage and tumor formation.

Green tea catechins have also been shown to possess antibiotic properties due to their role in disrupting a specific stage of the bacterial DNA replication process.[12]

Catechins, when combined with habitual exercise, have been shown to delay some forms of aging. Mice fed catechins showed decreased levels of aging. Oxidative stress was lowered in cell mitochondria, as well as increase in mRNA transcription of mitochondria related proteins. [13]

The Lancet medical journal has warned[14] against increasing one’s intake of dark chocolate in order to improve health, because the beneficial compounds are sometimes removed due to their bitter taste without an indication on the label, and because the fat, sugar, and calories of chocolate increase the risk for heart disease, unless balanced by a reduction of their intake in other foods.

In 2008 UCLA cancer researchers found that study participants who ate foods containing certain flavonoids seemed to be protected from developing lung cancer. Dr. Zuo-Feng Zhang, of the UCLA's Jonsson Cancer Center and a professor of public health and epidemiology at the UCLA School of Public Health said the flavonoids that appeared to be the most protective included catechin, found in strawberries and green and black teas; kaempferol, found in brussel sprouts and apples; and quercetin, found in beans, onions and apples.[15]

Catechin and epicatechin are also selective monoamine oxidase inhibitors (MAOIs) of type MAO-B.[16]

[edit] See also

v • d • e
Types of Phenylpropanoids
Phenylpropanoids
v • d • e
Types of Flavonoids
Flavones:
Isoflavones:
Flavonols:
Flavanones:
3-Hydroxyflavanones:
Flavan-3-ols:
Anthocyanidins:
Misc:
Major families of biochemicals
Saccharides/Carbohydrates/Glycosides · Amino acids/Peptides/Proteins/Glycoproteins · Lipids/Terpenes/Steroids/Carotenoids · Alkaloids/Nucleobases/Nucleic acids · Cofactors/Flavonoids/Polyketides/Tetrapyrroles

[edit] References

  1. ^ Zheng LT, Ryu GM, Kwon BM, Lee WH, Suk K (June 2008). "Anti-inflammatory effects of catechols in lipopolysaccharide-stimulated microglia cells: inhibition of microglial neurotoxicity". Eur. J. Pharmacol. 588 (1): 106–13. doi:10.1016/j.ejphar.2008.04.035. PMID 18499097. http://linkinghub.elsevier.com/retrieve/pii/S0014-2999(08)00455-X. 
  2. ^ Balentine DA, Harbowy ME, Graham HN (1998). "Tea: the Plant and its Manufacture; Chemistry and Consumption of the Beverage". in Spiller GA. Caffeine. Boca Raton: CRC Press. ISBN 0-8493-2647-8. 
  3. ^ Hammerstone JF, Lazarus SA, Schmitz HH (August 2000). "Procyanidin content and variation in some commonly consumed foods". J. Nutr. 130 (8S Suppl): 2086S–92S. PMID 10917927. http://jn.nutrition.org/cgi/pmidlookup?view=long&pmid=10917927. 
  4. ^ Ruidavets J, Teissedre P, Ferrières J, Carando S, Bougard G, Cabanis J (November 2000). "Catechin in the Mediterranean diet: vegetable, fruit or wine?". Atherosclerosis 153 (1): 107–17. PMID 11058705. http://linkinghub.elsevier.com/retrieve/pii/S0021915000003774. 
  5. ^ Mabry, Helga; Harborne, J. B.; Mabry, T. J. (1975). The Flavonoids. London: Chapman and Hall. ISBN 0-412-11960-9. 
  6. ^ Bais HP, Walker TS, Stermitz FR, Hufbauer RA, Vivanco JM (April 2002). "Enantiomeric-dependent phytotoxic and antimicrobial activity of (±)-catechin. A rhizosecreted racemic mixture from spotted knapweed". Plant Physiol. 128 (4): 1173–9. doi:10.1104/pp.011019. PMID 11950966. http://www.plantphysiol.org/cgi/content/full/128/4/1173. 
  7. ^ Chyu KY (May 2004). "Differential effects of green tea-derived catechin on developing versus established atherosclerosis in apolipoprotein E-null mice". Circulation 109 (20): 2448–53. doi:10.1161/01.CIR.0000128034.70732.C2. PMID 15136500. http://www.circ.ahajournals.org/cgi/content/full/109/20/2448. 
  8. ^ Mittal A, Pate MS, Wylie RC, Tollefsbol TO, Katiyar SK (March 2004). "EGCG down-regulates telomerase in human breast carcinoma MCF-7 cells, leading to suppression of cell viability and induction of apoptosis". Int. J. Oncol. 24 (3): 703–10. PMID 14767556. 
  9. ^ BBC news: Cocoa nutrient for lethal ills
  10. ^ Science Daily March 12, 2007.
  11. ^ Katiyar S, Elmets CA, Katiyar SK (May 2007). "Green tea and skin cancer: photoimmunology, angiogenesis and DNA repair". J. Nutr. Biochem. 18 (5): 287–96. doi:10.1016/j.jnutbio.2006.08.004. PMID 17049833. http://linkinghub.elsevier.com/retrieve/pii/S0955-2863(06)00190-2. 
  12. ^ Gradisar H, Pristovsek P, Plaper A, Jerala R (January 2007). "Green tea catechins inhibit bacterial DNA gyrase by interaction with its ATP binding site". J. Med. Chem. 50 (2): 264–71. doi:10.1021/jm060817o. PMID 17228868. 
  13. ^ Murase T, Haramizu S, Ota N, Hase T (July 2008). "Tea catechin ingestion combined with habitual exercise suppresses the aging-associated decline in physical performance in senescence-accelerated mice". Am. J. Physiol. Regul. Integr. Comp. Physiol. 295 (1): R281–9. doi:10.1152/ajpregu.00880.2007. PMID 18480242. http://ajpregu.physiology.org/cgi/pmidlookup?view=long&pmid=18480242. 
  14. ^ The Lancet Student » Archive » The Lancet Digest December 22nd 2007
  15. ^ UCLA news 2008 - Fruits, vegetables, teas may protect smokers from lung cancer
  16. ^ Hou WC, Lin RD, Chen CT, Lee MH (August 2005). "Monoamine oxidase B (MAO-B) inhibition by active principles from Uncaria rhynchophylla". J Ethnopharmacol 100 (1-2): 216–20. doi:10.1016/j.jep.2005.03.017. PMID 15890481. 

[edit] External links

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