Anti-Cancer Compound in Green Tea Identified

Tue Mar 15, 2005 12:13 AM ET

By Patricia Reaney

LONDON (Reuters) - Spanish and British scientists have discovered how
green tea helps to prevent certain types of cancer.
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 in green tea prevents cancer cells from growing by binding to a
specific enzyme.

"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, " Professor Roger Thorneley, of JIC, told Reuters.

"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 findings could also explain why women who drink large amounts of
green tea around the time they conceive and early in their pregnancy may
have an increased risk of having a child with spina bifida or other
neural tube disorders.
Women are advised to take supplements of folic acid because it protects
against spina bifida. But large amounts of green tea could decrease the
effectiveness of folic acid.

"This enzyme, (DHFR), is the one folic acid supplements are given for.
Folic acid deficiency leads to neural tube development defects,"
Thorneley added.  

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