Epigallocatechin gallate

• EGCG
• Tea catechin
• (2R,3R)-2-(3,4,5-Trihydroxyphenyl)-3,4-dihydro-1(2H)-benzopyran-3,5,7-triol-3-(3,4,5-trihydroxybenzoat)

White solid

Fixed

217 ° C.

2170 mg · kg -1 ( LD50, mouse, oral)

Template: Infobox chemical / molecular formula search available

Epigallocatechin gallate, Eng. Epigallocatechin gallate ( EGCG), is a carboxylic acid ester of gallic acid with the alcohol and catechin epigallocatechin. The antioxidant accounts for about a third of the dry weight of green tea. In black tea, the proportion of catechins is much lower, as the catechins to oligomeric theaflavins react due to the fermentation. The connection is said to have a positive effect on health.

Medical aspects

Angiogenesis

Various experiments that EGCG has an anti-angiogenic effect ( inhibition of growth of blood vessels ). After xenotransplantation of diseased human endometrial tissue in mice, this effect could be demonstrated. The human origin of the fabric can have an effect in human endometriosis suspect. Furthermore, similar effects have been demonstrated by in vitro and in vivo experiments with hamsters.

An anti-angiogenic effect of EGCG could also be used to attenuate the growth of tumor tissue. Tumors also require blood vessels to be adequately supplied with oxygen and nutrients. EGCG inhibits the activity of growth factors that are required in the mechanism of angiogenesis, such as the pro- angiogenic interleukin -8. The binding of the peptide hormone VEGF to its receptor is inhibited by EGCG. In a mouse model of gastric cancer, inhibition of VEGF - dependent angiogenesis EGCG was shown.

Also a positive influence on the elasticity of blood vessels ( endothelial function), which plays a central role in the development of atherosclerosis ( atherogenesis ), has been reported.

Cell cycle

EGCG also supports the tumor suppressor p27, which controls the cell cycle and prevent a runaway cell division. It inhibits this growth factors by binding to them.

Neurogenesis

Neurodegenerative diseases such as Alzheimer's and Parkinson's disease are caused by the formation of amyloid fibrils. EGCG prevents their formation by binding to the native, still unfolded polypeptide chains. This spherical oligomers instead of toxic, harmless fibrous amyloid fibrils formed. Studies suggest that EGCG may dissolve plaques. In the model organism color mouse has been shown that after six months of treatment, the EGCG plaque burden was reduced by in each case 54, 43 and 58% in the cortex, hippocampus and entorhinal cortex.

Immunology

A Japanese research group showed in laboratory tests that EGCG can prevent the invasion of HIV virus in T lymphocytes, as it has such as the HI virus has an affinity to the CD4 molecules on the cell surface of T lymphocytes. By binding to the CD4 receptor of the HIV EGCG can not dock with the T lymphocytes, and thus no longer infect.

Even against the influenza A virus to EGCG was effective. Both in experiments with cell cultures and in animal studies, it could significantly reduce the spread of the virus and in infected mice, the median survival time to increase significantly.

Moreover, studies have in the Multiple Sclerosis Research suggests that both EGCG protect nerve cells in the central nervous system from damage, as well as misguided T- lymphocytes, which are responsible for the disease, can regulate. The animal model of multiple sclerosis - - As the progression of experimental autoimmune encephalomyelitis was on administration of EGCG significantly milder than in animals that did not receive EGCG.

EGCG also neutralizes TNF- α, and thus reduces the production of interleukin -6 and -8, which partly explains the immunosuppressive effect.

Metabolism

Catechins are widely regarded as a scavenger of reactive oxygen (ROS ) and nitrogen species (RNS). These two types of compounds are responsible for the oxidative damage to DNA.

Activity at the cannabinoid receptor 1

EGCG binds to the cannabinoid receptor 1 with a binding affinity of K i = 33.6 uM.

Potent inhibition of 11beta -hydroxysteroid dehydrogenase 1

A study from 2014 found that epigallocatechin gallate green tea the 11beta -hydroxysteroid dehydrogenase 1 potently inhibits cortisol is therefore less available and thus possibly parts of the health-promoting properties of green tea could be explained as cortisol a crucial role include plays in the psychophysiological stress response.

Heat stability and epimerization

(-)- Gallocatechin to (-) In an environment with high temperatures epimerization of EGCG - is, and the decomposition possible. The exposure in boiling water for 30 minutes resulting in a 12.4 % reduction in the total amount of EGCG. In the short brewing time of tea a reduction of EGCG is therefore irrelevant.

Interact with milk proteins

Various studies indicate that the proteins contained in milk ( whey proteins, caseins ) react with EGCG and other catechins. A reduction of the (-)- EGCG content of green tea with the addition of milk was observed.