EGCG Research Updates
EGCG Research: EGCG And Verapamil
A different drug study explored the effects of EGCG combined with verapamil in animals.
Verapamil is another class of calcium channel blockers used for high blood pressure, chest pain, and irregular heart beat or arrhythmia.
Researchers found up to 111% increase in verapamil in animals when administered with EGCG, possibly mediated by P-glycoprotein (Chung JH, Effects of oran epigallocatechin gallate on the oral pharmacokinetics of verapamil in rats, Biopharmaceutics Drug Disp., February 2009).
Again this is preliminary research and has not been studied with humans.
EGCG Research: EGCG AND Diltiazem
Diltiazem, a prescription drug, is in a group of benzothiazepine calcium channel blockers used for high blood pressure, chest pain, and irregular heart beats.
A new animal study has explored the bioavailability of diltiazem when combined with EGCG from green tea.
Higher amounts of EGCG increased the presence of this drug in the body up to 1.76 times more than in the control group. The mechanisms for the enhanced bioavailability included inhibiting cytocrome P450 metabolism and reducing the loss of diltiazem in the intestine from P-glycoprotein action (LI C, Effects of epigallocatechin gallate on the bioavailability and pharmocokinetics of diltiazem in rats. Die Pharmazie, November 2008).
This is a preliminary study and has not yet been explored in humans.
EGCG Research: Gastric Cancer
A new study shows that EGCG, the primary antioxidant polyphenol from green tea, reduces the development of tumors in the gastric system.
This preliminary animal study found that EGCG reduced tumor growth by an average of over 60%. EGCG also reduced other tumor promoting factors like angiogenesis (blood supply) to the gastric tumors.
Researchers determined that a primary chemical pathway involved reduced activation of STAT3 which led to reduced tumor growth (Zhu BH, Epigallocatechin-3-gallate inhibits growth and angiogenesis of gastric cancer and its molecular mechanism, Zhonghua Wei Chang Wai Ke Za Zhi, January 2009).
EGCG Research: EGCG, EGC, or ECG And Melanoma?
Both green and black tea have shown strong activity in preventing the initiation, progression, and proliferation of skin cancer in hundreds of studies.
One study has examined the effectiveness of EGCG, EGC, and ECG, the primary catechin antioxidants in green tea, against 8 different melanoma cancer cell lines that had metastasized to either the lymph nodes or distant organs.
While overall cancer growth suppression and dead cancer cell counts were higher with EGCG, the other two catechins from green tea-- EGC and ECG--were as effective at lower concentrations than EGCG with some of the 8 cell different cell lines.
The authors state that knowing which catechin is more effective with each different type of cancer is important before chemopreventive trials using green tea are conducted (Ravindranath MH, Differential Growth Suppression of Human Melanoma Cells by Tea (Camellia sinensis) Epicatechins (ECG, EGC and EGCG), Evidence Based Complementary and Alternative Medicine, January 2008).
The largest percentage of green tea catechins is EGCG, but green tea at "cup of tea strength" also includes EGC and ECG.
Melanoma skin cancer risk increases with exposure to the sun and the CDC recommends avoiding strong sun from 10 AM to 4 PM, covering your skin with clothing and large hats, sunblocker glasses, and suncreen.
There are over 50,000 new cases each year in the U. S. with almost 8,000 deaths annually (CDC 2004).
EGCG Research: EGCG Lowers Blood Pressure
In a study testing the effects of EGCG from green tea on insulin resistance, researchers found that EGCG significantly lowered blood pressure, and improved psychological mood.
In an 8 week study, 88 overweight men, age 40-65, received either two 400 mg. capsules of EGCG daily or a placebo.
While researchers found no association between EGCG and insulin sensitivity, insulin secretion, or glucose tolerance with this study, they did find a significant decrease in high blood pressure, specifically a moderate decrease in diastolic pressure.
Also men receiving EGCG reported a significantly improved positive psychological mood compared to those receiving placebo (Brown AL, Effects of dietary supplementation with the green tea polyphenol epigallocatechin-3-gallate on insulin resistance and associated metabolic risk factors: randomized controlled trial, British Journal of Nutrition, August 2008).
EGCG News: Green Tea And Atherosclerosis
Atherosclerosis is the damage to blood vessels associated with high cholesterol.
It can lead to arteriosclerosis and is a risk factor for heart attacks and strokes.
A new study has found that ECG (epicatechin gallate), a polyphenol catechin in green tea, shows anti-atherosclerotic activity by targeting foamy macrophages directly in the atherosclerotic lesion damage. Foamy macrophage cells are an important part of deeper lesions.
Preliminary cell studies showed significant accumulation of ECG in the foamy macrophage cells of human atherosclerotic lesions and found that ECG could suppress part of the DNA gene expression that leads to the formation of foamy macrophage cells (Kawai Y, (-)-Epicatechin gallate accumulates in foamy macrophages in human atherosclerotic aorta: Implication in the anti-atherosclerotic actions of tea catechins, Biochemical and Biophysical Research Communications, August 2008).
ECG is one of several antioxidant catechins found primarily in green tea, each one with different functions. EGCG is the most powerful, and most studied green tea antioxidant.
EGCG Research: Green Tea And Alcohol-damaged Liver
Excess alcohol not only damages the liver, but can be lethal.
While there are many studies showing that green tea can help protect the liver from damage, all mechanisms have not been clearly identified yet.
A preliminary green tea research study using alcohol-damaged liver cells found that green tea reduced liver cell damage as measured by gamma-glutamyl transferase (GGT).
Using HepG2 cells, researchers exposed the cells to a lethal amount of ethanol alcohol, and tracked GGT. GGT is used clinically as a measure of alcohol toxicity.
They found that EGCG (epigallocatechin gallate), the primary antioxidant polyphenol from green tea, could effectively reduce GGT and prevent liver cell death. There was no protection from the caffeine or theanine in the tea. But EGCG did not reduce the intracellular gluthathione loss caused by ethanol alcohol.
Researchers suggest that EGCG may provide a new strategy to be included with other GGT inhibitors for reducing liver damage from ethanol (Lee SI, Effect of green tea and (-)-epigallocatechin gallate on ethanol-induced toxicity in HepG2 cells, Phytotherapy Research March 2008).
EGCG Research: Nerve Degeneration Diseases
There is growing research that oxidative stress is involved in the damage that occurs with neurodegenerative diseases.
Part of that damage comes from free radicals and abnormal metal metabolism. A great deal of research has focused on solving these problems separately.
Now researchers are studying natural polyphenols like EGCG from green tea because these chemicals can show broad spectrum benefits that include both antioxidant activity against free radicals and normalization of metal metabolism.
In a preliminary EGCG research cell study, researchers have identified more genes and proteins that can be used as biomarkers to study the unique metabolic benefits of EGCG (Weinreb O, The application of proteomics for studying the neurorescue activity of the polyphenol (-)-epigallocatechin-3-gallate, Archives of Biochemistry & Biophysics, January 2008).
These new biomarkers include:
- protein kinase C epsilon
- ATP synthase mitochondrial F1 complex beta
- nerve vascular growth factor inducible precursor
- and, hypoxia inducible factor-1 alpha.
EGCG (epigallocatechin gallate) is the primary polyphenol flavonoid catechin in green tea.
EGCG Research: Glaucoma and EGCG Research
Many laboratory studies have shown that green tea and EGCG can protect the retina and eye from some of the damage from free radical oxidation, glutamate toxicity, and post-ischemia loss of blood supply.
Now a new animal study shows that EGCG from green tea in the drinking water provides protection from glaucoma.
EGCG was given to half the animals for three days before administering increased intraocular pressure, and for five days afterwards.
Damage parameters included localization of Thy-1 and choline acetyltransferase, electroretinogram amplitudes, proteins, mRNAs, and capsase activation.
The results showed that drinking EGCG from green tea statistically reduced the damage in the animal glaucoma model (Zhang B, Brain Research, 2007).
Researchers state that the use of EGCG from green tea is supported in the treatment of glaucoma for its safe profile, broad spectrum nerve protection, and reduction of damage to the eye from blood loss and other damaging risk factors.
This research is still preliminary and you should consult with your health care provider for glaucoma treatment plans.
EGCG Research: Arthritis and EGCG research
Recent work with EGCG, the primary polyphenol antioxidant of green tea has shown remarkable protection against arthritis.
Using fibroblast cells from the damaged joints of rheumatoid arthritis patients, researchers found that exposure to EGCG from green tea blocks chemicals that can cause bone damage.
At higher doses, EGCG blocked production from the following inflammatory molecules involved in rheumatoid arthritic disease: interleukin-1beta (IL-1beta)-induced production of RANTES (CCL5), epithelial neutrophil-activating peptide 78 (ENA-78/CXCL5), growth-regulated oncogene alpha (GROalpha/CXCL1), and IL-1beta-induced MMP-2 activity. It reduced monocyte chemo-attractant protein 1 (MCP-1/CCL2) by 48%.
Lower doses only reduced these chemicals. EGCG was nontoxic to the living fibroblast cells even at higher doses (Ahmed S, Arthritis Rheum, 2006).
Other green tea studies have found significant prevention of arthritis in animals.
Cell studies like the above are considered preliminary.
The CDC, 2003 report says rheumatoid arthritis and osteoarthritis affect 46 million (21.6% of adults) in the United States alone. As baby boomers age, this number may double. The annual cost of arthritis is $128 billion for the United States (direct plus indirect costs).
Some tea researchers relate their experimental design to people drinking about four 8-ounce cups of green tea throughout the day.
Four cups of green tea daily costs less than $10 a month in the United States.
EGCG Research: Protection Against Heart Attack Damage
A new study from India tested EGCG, the primary antioxidant polyphenol from green tea, in an animal model of heart attacks.
Without EGCG, animals after a heart attack showed significant increases in levels of lipid peroxidation products, levels of thiobarbituric acid reactive substances, and uric acid. At the same time, there was a significant decrease in the antioxidant activities of superoxidide dismutase, catalase, glutathione peroxidase, and other glutathione compounds in the heart as well as significant decreases in vitamin C and E.
When test animals were given EGCG daily for 21 days prior to the induced heart attack, the opposite was seen. There was a significant decrease in lipid peroxidation compounds and significant protection of antioxidants.
The greatest protection was with the larger daily doses of 30mg/kg of EGCG compared to lower doses of 10mg/kg or 20mg/kg (Devika P, Biomedical Pharmacotherapy, 2007).
This is a preliminary study. However, there are many studies of large, longitudinal databases of human health and nutrition that show a large reduction in heart attacks among people who drink 5 or more cups of tea daily.
Heart disease is usually the first or second leading cause of death in industrialized societies.
EGCG Research: EGCG Helps Researchers
Researchers have just announced a new way that EGCG, an antioxidant catechin from green tea, could help the development of new drugs with fewer side effects.
One of the ways new drugs are developed is by targeting a specific cellular pathway. In the case of bacteria, a good target is an enzyme called DNA gyrase.
DNA gyrase is required for bacterial reproduction. By stopping bacterial reproduction, researchers hope to stop debilitating infections.
But bacterial DNA gyrase cannot act without the help of the energy molecule ATP, or adenosine triphosphate.
Researchers seeking antibacterial drugs have tried to target the ATP binding site on DNA gyrase to stop its energy source, but so far have created chemicals with limited usefulness due to side effects.
Now researchers in Slovenia have been able to track EGCG from green tea as it inhibits DNA gyrase. Using NMR spectroscopy, they have followed EGCG to the specific binding site on DNA gyrase where EGCG blocks ATP and thus prevents bacterial reproduction (Jerala R, Journal Medicinal Chemistry, 2007).
This kind of technology has also helped HIV research show EGCG from green tea binding to a specific site on healthy cells used by HIV to enter and infect the cells. When EGCG was present, it could block HIV entry into the cell.
Researchers hope that by following the successful protection of green tea's EGCG biochemistry, they can make proprietary drugs that mimic its effects.
Hmmmmm.......
EGCG Research: Green Tea EGCG, Parkinson's, and Alzheimer's Disease
A preliminary study suggests that EGCG from green tea may protect against Alzheimer's disease and Parkinson's disease.
Researchers used a laboratory model of Parkinson's disease where neuronal cells are damaged by paraquat, an herbicide used worldwide that is also toxic to dopaminergic brain cells associated with Parkinson's and some Alzheimer's.
They found that adding EGCG (epigallocatechin gallate) from green tea reduced the deaths of paraquat damaged nerve cells. Protecting these specialized cells which are frequently damaged in Parkinson's disease is still only preliminary evidence for EGCG benefit. Larger studies with humans need to be explored.
A possible explanation is that EGCG protects the cells by reducing enzymes and proteins that promote cell death or apoptosis, and by maintaining mitochondrial membrane integrity (Hou R, Cell Biology International, 2007).
Daily green tea is the largest source of EGCG, a very powerful antioxidant with broad spectrum benefits.
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This page last updated by Sharon Jones.
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