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November 13, 2006

Anti-Cancer Compound in Green Tea Identified

Topics: Medical Science News

green_tea3.jpgDihydrofolate Reductase plays an important role in human physiology. The blocking of its enzymatic activity is a key element in treatment of many diseases, including cancer and AIDS related infections. PakTribune.com reports today that recently, researchers at the University of Murcia in Spain (UMU) and the John Innes Center (JIC) in Norwich, England have shown that a compound called EGCG (Epigallocatechin gallate) in green tea prevents cancer cells from growing by binding to the enzyme dihydrofolate reductase (DHFR):

[...] "We have shown for the first time that EGCG, which is present in green tea at relatively high concentrations, inhibits the enzyme dihydrofolate reductase (DHFR), which is a recognized, established target for anti-cancer drugs, " says Professor Roger Thorneley, of JIC.

"This is the first time, to our knowledge, a known target for an anti-cancer drug has been identified as being inhibited by EGCG," he added.

Green tea has about five times as much EGCG as regular tea, studies have shown. It decreased rates of certain cancers but scientists were not sure what compounds were involved or how they worked. Nor had they determined how much green tea a person would have to drink to have a beneficial effect, he said.

Thorneley said EGCG is probably just one of a number of anti-cancer mechanisms in green tea.

"We have identified this enzyme in tumour cells that EGCG targets and understand how it stops this enzyme from making DNA. This means we may be able to develop new anti-cancer drugs based on the structure of the EGCG molecule," Thorneley explained.

The scientists decided to look at ECGC after they realized its structure was similar to a cancer drug called methotrexate.

"We discovered that EGCG can kill cancer cells in the same way as methotrexate," Dr Jose Neptuno Rodriguez-Lopez, of UMU, a joint author of the research published in the journal Cancer Research.

EGCG binds strongly to DHFR, which is essential in both healthy and cancerous cells. But it does not bind as tightly as methotrexate, so its side effects on healthy cells could be less severe than those of the drug.

Thorneley said EGCG could be a lead compound for new anti-cancer drugs.

The article cautions that large amounts of green tea could decrease the effectiveness of folic acid and that Dihydrofolate Reductase is the enzyme that folic acid supplements are used to target.

Suggested reading - Biological effects of EGCG:

Epigallocatechin gallate (EGCG) is a potent antioxidant polyphenols of green tea, is associated with antioxidant, antitumor and antimutagenic activities. The antioxidant activity is at last 100 more times more effective than vitamin C and 25 times more effective than vitamin E at protecting cells and DNA from damage which are believed to be linked to cancer, heart disease and other potentially fatal illnesses. The biological benefits of EGCG are generally attributed to their antioxidant activity to scavenge free radical oxygen.

EGCG is the major component of the polyphenolic fraction of green tea. It make up about 10-50% of the total green tea catechins includeing epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate(ECG), epicatechin(EC), gallocatechin gallate (GCG), catechin are major catechin of green tea catechin. The antioxidant activity increased in the following order: EC

Many studies indicate EGCG play a role as,protect aganist free-radical DNA damage;protect aganist the effects of ionizing radiation and ultraviolet radiation;inhibit lipid peroxidation, decrease serum cholesterol levels, LDL, VLDL and triglycerides;interfere with the binding of cancer-causing agents to cellular DNA, help to neutralize dietary carcinogens;work with enzymes and other antioxidants in the intestine, liver and lungs to prevent the activation of certain carcinogens before they damage DNA;as a free radicals scavenger, combat the effects of pollution, sunlight and smoking, help skin from wrinkling and aging.

Posted by Richard at November 13, 2006 10:34 AM

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