Epigallocatechin gallate
Encyclopedia
Epigallocatechin gallate (EGCG), also known as epigallocatechin 3-gallate, is the ester of epigallocatechin and gallic acid
, and is a type of catechin.
EGCG is the most abundant catechin in tea
and is a potent antioxidant that may have therapeutic applications in the treatment of many disorders (e.g. cancer). It is found in green - but not black tea because during black tea production, the catechins are converted to theaflavins and thearubigins. In a high temperature environment, an epimerization change is more likely to occur; however as exposure to boiling water for 30 straight minutes only leads to a 12.4% reduction in the total amount of EGCG, the amount lost in a brief exposure is insignificant. In fact, even when special conditions were used to create temperatures well over that of boiling water, the amount lost scaled up only slightly.
EGCG can be found in many supplements.
infection, where EGCG has been shown to reduce plaques related to AIDS-related dementia in the laboratory, as well as block gp120
. However, these effects have yet to be confirmed in live human trials, and it does not imply that green tea will cure or block HIV infection, but it may help regulate viral load
as long as it is not involved in adverse drug reactions. The concentrations of EGCG used in the studies could not be reached by drinking green tea. More study into EGCG and HIV is currently underway.
s – can be beneficial in treating brain, prostate, cervical and bladder cancers. EGCG has been shown to bind and inhibit the anti-apoptotic protein Bcl-xl
, which has been implicated in both cancer cell and normal cell survival.
. Research results may suggest that EGCG (e.g,. in green tea) can turn on the body’s defense system against TNF-alpha proteins, which are involved in systemic inflammation.
showed that, in contrast to the myriad benefits commonly associated with green tea and green tea extract
(GTE), EGCG binds with the anti-cancer drug Velcade, significantly reducing its bioavailability and thereby rendering it therapeutically useless. Dr. Schönthal, who headed the study, suggests that consumption of green tea and GTE products be strongly contraindicated for patients undergoing treatment for multiple myeloma and mantle cell lymphoma. EGCG has a slight stimulatory effect due to it increasing adrenaline levels.Epigallocatechin-3-gallate, may reduce the bioavaialbilty
of the drug sunitinib
when they are taken together.
, similar to some chemotherapeutic anticancer drugs, for example, etoposide
and doxorubicin
.
This property may be responsible for observed anticarcinogenic effects; however, there is also a possible carcinogenic potential. High intake of polyphenolic compounds during pregnancy is suspected to increase risk of neonatal leukemia. Bioflavonoid supplements should not be used by pregnant women. Maternal consumption of tea
or coffee during pregnancy may elevate the risk of childhood malignant central nervous system (CNS) tumours through unknown mechanisms.
Gallic acid
Gallic acid is a trihydroxybenzoic acid, a type of phenolic acid, a type of organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. The chemical formula is C6H23COOH. Gallic acid is found both free and as part of...
, and is a type of catechin.
EGCG is the most abundant catechin in tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...
and is a potent antioxidant that may have therapeutic applications in the treatment of many disorders (e.g. cancer). It is found in green - but not black tea because during black tea production, the catechins are converted to theaflavins and thearubigins. In a high temperature environment, an epimerization change is more likely to occur; however as exposure to boiling water for 30 straight minutes only leads to a 12.4% reduction in the total amount of EGCG, the amount lost in a brief exposure is insignificant. In fact, even when special conditions were used to create temperatures well over that of boiling water, the amount lost scaled up only slightly.
EGCG can be found in many supplements.
EGCG and HIV
There has been research investigating the benefit of EGCG from green tea in the treatment of HIVHIV
Human immunodeficiency virus is a lentivirus that causes acquired immunodeficiency syndrome , a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive...
infection, where EGCG has been shown to reduce plaques related to AIDS-related dementia in the laboratory, as well as block gp120
Gp120
Envelope glycoprotein GP120 is a glycoprotein exposed on the surface of the HIV envelope. The 120 in its name comes from its molecular weight of 120 kilodaltons...
. However, these effects have yet to be confirmed in live human trials, and it does not imply that green tea will cure or block HIV infection, but it may help regulate viral load
Viral load
Viral load is a measure of the severity of a viral infection, and can be calculated by estimating the amount of virus in an involved body fluid. For example, it can be given in RNA copies per milliliter of blood plasma...
as long as it is not involved in adverse drug reactions. The concentrations of EGCG used in the studies could not be reached by drinking green tea. More study into EGCG and HIV is currently underway.
EGCG and Cancer
There is increasing evidence to show that EGCG – along with other flavonoidFlavonoid
Flavonoids , are a class of plant secondary metabolites....
s – can be beneficial in treating brain, prostate, cervical and bladder cancers. EGCG has been shown to bind and inhibit the anti-apoptotic protein Bcl-xl
Bcl-xL
B-cell lymphoma-extra large is a transmembrane molecule in the mitochondria. It is involved in the signal transduction pathway of the FAS-L. It is one of several anti-apoptotic proteins which are members of the Bcl-2 family of proteins. It has been implicated in the survival of cancer cells. Other...
, which has been implicated in both cancer cell and normal cell survival.
EGCG and Sjögren's syndrome
According to the research led at Medical College of Georgia, EGCG may help protect against some autoimmune diseases, including Sjögren's syndromeSjögren's syndrome
Sjögren's syndrome , also known as "Mikulicz disease" and "Sicca syndrome", is a systemic autoimmune disease in which immune cells attack and destroy the exocrine glands that produce tears and saliva....
. Research results may suggest that EGCG (e.g,. in green tea) can turn on the body’s defense system against TNF-alpha proteins, which are involved in systemic inflammation.
EGCG and endometriosis
Xu et al. found that antiangiogenic effects of EGCG inhibits the growth of blood vessels and thus reduces lesion size in experimental endometriosis (mouse model).Drug Interactions
A recent study using mouse models at the University of Southern CaliforniaUniversity of Southern California
The University of Southern California is a private, not-for-profit, nonsectarian, research university located in Los Angeles, California, United States. USC was founded in 1880, making it California's oldest private research university...
showed that, in contrast to the myriad benefits commonly associated with green tea and green tea extract
Green tea extract
A green tea extract is a herbal derivative from green tea leaves . Containing antioxidant ingredients – mainly green tea catechins – green tea and its derivatives are sought-after amongst people who pursue health....
(GTE), EGCG binds with the anti-cancer drug Velcade, significantly reducing its bioavailability and thereby rendering it therapeutically useless. Dr. Schönthal, who headed the study, suggests that consumption of green tea and GTE products be strongly contraindicated for patients undergoing treatment for multiple myeloma and mantle cell lymphoma. EGCG has a slight stimulatory effect due to it increasing adrenaline levels.Epigallocatechin-3-gallate, may reduce the bioavaialbilty
Bioavailability
In pharmacology, bioavailability is a subcategory of absorption and is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. By definition, when a medication is administered...
of the drug sunitinib
Sunitinib
Sunitinib is an oral, small-molecule, multi-targeted receptor tyrosine kinase inhibitor that was approved by the FDA for the treatment of renal cell carcinoma and imatinib-resistant gastrointestinal stromal tumor on January 26, 2006...
when they are taken together.
Possible carcinogenic potential
EGCG was, among other tea polyphenols, found to be a strong topoisomerase inhibitorTopoisomerase inhibitor
Topoisomerase inhibitors are agents designed to interfere with the action of topoisomerase enzymes , which are enzymes that control the changes in DNA structure by catalyzing the breaking and rejoining of the phosphodiester backbone of DNA strands during the normal cell cycle.In recent years,...
, similar to some chemotherapeutic anticancer drugs, for example, etoposide
Etoposide
Etoposide phosphate is an anti-cancer agent. It is known in the laboratory as a topoisomerase poison. Etoposide is often incorrectly referred to as a topoisomerase inhibitor in order to avoid using the term "poison" in a clinical setting...
and doxorubicin
Doxorubicin
Doxorubicin INN is a drug used in cancer chemotherapy. It is an anthracycline antibiotic, closely related to the natural product daunomycin, and like all anthracyclines, it works by intercalating DNA....
.
This property may be responsible for observed anticarcinogenic effects; however, there is also a possible carcinogenic potential. High intake of polyphenolic compounds during pregnancy is suspected to increase risk of neonatal leukemia. Bioflavonoid supplements should not be used by pregnant women. Maternal consumption of tea
Tea
Tea is an aromatic beverage prepared by adding cured leaves of the Camellia sinensis plant to hot water. The term also refers to the plant itself. After water, tea is the most widely consumed beverage in the world...
or coffee during pregnancy may elevate the risk of childhood malignant central nervous system (CNS) tumours through unknown mechanisms.
Spectral data
| UV-Vis | |
|---|---|
| Retention time | 34.5 min (C18 RP, Acetonitrile 80%) |
| Lambda-max | 274 and 240 nm Nanometre A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter... (see picture) |
| Extinction coefficient Molar absorptivity The molar absorption coefficient, molar extinction coefficient, or molar absorptivity, is a measurement of how strongly a chemical species absorbs light at a given wavelength... |
|
| IR Infrared Infrared light is electromagnetic radiation with a wavelength longer than that of visible light, measured from the nominal edge of visible red light at 0.74 micrometres , and extending conventionally to 300 µm... |
|
| Major absorption bands | cm−1 |
| NMR NMR spectroscopy Nuclear magnetic resonance spectroscopy, most commonly known as NMR spectroscopy, is a research technique that exploits the magnetic properties of certain atomic nuclei to determine physical and chemical properties of atoms or the molecules in which they are contained... |
|
| Proton NMR Proton NMR Proton NMR is the application of nuclear magnetic resonance in NMR spectroscopy with respect to hydrogen-1 nuclei within the molecules of a substance, in order to determine the structure of its molecules. In samples where natural hydrogen is used, practically all of the hydrogen consists of the... (500 MHz, CD3OD): d : doublet, dd : doublet of doublets, m : multiplet, s : singlet |
δ Chemical shift In nuclear magnetic resonance spectroscopy, the chemical shift is the resonant frequency of a nucleus relative to a standard. Often the position and number of chemical shifts are diagnostic of the structure of a molecule... : |
| Carbon-13 NMR Carbon-13 NMR Carbon-13 NMR is the application of nuclear magnetic resonance spectroscopy to carbon. It is analogous to proton NMR and allows the identification of carbon atoms in an organic molecule just as proton NMR identifies hydrogen atoms... |
|
| Other NMR data | |
| MS Mass spectrometry Mass spectrometry is an analytical technique that measures the mass-to-charge ratio of charged particles.It is used for determining masses of particles, for determining the elemental composition of a sample or molecule, and for elucidating the chemical structures of molecules, such as peptides and... |
|
| Masses of main fragments |
ESI-MS [M+H]+ m/z : 459 |
See also
- Epigallocatechin
- Proteasome inhibitorProteasome inhibitorProteasome inhibitors are drugs that block the action of proteasomes, cellular complexes that break down proteins, like the p53 protein. Proteasome inhibitors are being studied in the treatment of cancer.-Examples:...
- Health benefits of teaHealth benefits of teaThe health effects of tea have been examined ever since the first infusions of Camellia sinensis about 4700 years ago in China. The legendary emperor Shennong claimed in The Divine Farmer's Herb-Root Classic that Camellia sinensis infusions were useful for treating conditions including tumors,...
- TheaflavinTheaflavinTheaflavin and its derivatives, known collectively as theaflavins, are antioxidant polyphenols that are formed from flavan-3-ols such as in tea leaves during the enzymatic oxidation of tea leaves, such as in black tea. Theaflavins are types of thearubigins, and are therefore reddish in color...
- TanninTanninA tannin is an astringent, bitter plant polyphenolic compound that binds to and precipitates proteins and various other organic compounds including amino acids and alkaloids.The term tannin refers to the use of...
- Phenolic content in tea
- Green tea extractGreen tea extractA green tea extract is a herbal derivative from green tea leaves . Containing antioxidant ingredients – mainly green tea catechins – green tea and its derivatives are sought-after amongst people who pursue health....
- List of phytochemicals in food