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Green
Tea's Cancer-Fighting Allure
Becomes More Potent
Green tea’s ability to fight cancer is
even more potent and varied than scientists suspected, say researchers who
have discovered that chemicals in green tea shut down one of the key
molecules that tobacco relies upon to cause cancer. It’s a find that
could help explain why people who drink green tea are less likely to
develop cancer.
The finding by scientists at the
University of Rochester’s Environmental Health Science Center appears in
the July 21 issue of Chemical Research in Toxicology, published by
the American Chemical Society.
Graduate student Christine Palermo and
adviser Thomas Gasiewicz, Ph.D., set out to measure the effects of the
chemicals found in green tea on a molecule known as the aryl hydrocarbon
(AH) receptor, a molecule that frequently plays a role in turning on genes
that are oftentimes harmful. Gasiewicz has previously shown how both
tobacco smoke and dioxin manipulate the molecule – a favorite target of
toxic substances – to cause havoc within the body, and currently he’s
working with scientists at the James P. Wilmot Cancer Center to clarify
exactly how substances like tobacco smoke cause cancer.
The team isolated the chemicals that make
up green tea and found two that inhibit AH activity. The two substances,
epigallocatechingallate (EGCG) and epigallocatechin (EGC), are close
molecular cousins to other flavonoids found in broccoli, cabbage, grapes
and red wine that are known to help prevent cancer.
While green tea has been much-ballyhooed
for its anti-cancer effects as well as other purported abilities such as
preventing rheumatoid arthritis and lowering cholesterol, just how the
substance works has been a mystery. Scientists do know that green tea
contains chemicals that are anti-oxidants and quench harmful molecules.
But its effects on the AH receptor have not been thoroughly evaluated
until now.
“It’s likely that the compounds in
green tea act through many different pathways,” says Gasiewicz,
professor and chair of Environmental Medicine and director of
Rochester’s Environmental Health Science Center. “Green tea may work
differently than we thought to exert its anti-cancer activity.”
Gasiewicz and Palermo showed that the
chemicals shut down the AH receptor in cancerous mouse cells, and early
results indicate the same is true in human cells as well.
In the laboratory the AH-inhibiting
effects of green tea become evident when EGCG and EGC reach levels typical
of those found in a cup of green tea. But the scientists say that how
green tea is metabolized by the body is crucial to its effectiveness, and
that results in the laboratory don’t necessarily translate directly to
the dinner table.
“Right now we don’t know if drinking
the amount of green tea that a person normally drinks would make a
difference, but the work is giving us insight into how the proteins
work,” says Palermo, who enjoys cold green tea herself. “There are a
lot of differences between various kinds of green tea, so a lot more
research is needed.”
For this work Palermo received the award
for best poster in the chemical carcinogenesis specialty section at the
meeting of the Society of Toxicology in March. Now she is studying exactly
how green tea inhibits the AH receptor. After she graduates Palermo plans
to study links between environmental agents and childhood leukemia.
In addition to Palermo and Gasiewicz,
other authors are former post-doctoral associate Jose Martin Hernando and
chemist Andrew Kende, who teased apart the components of green tea
extract; and Stephen Dertinger, a former student who first had the idea to
test green tea’s effects on the AH receptor. The work was funded by the
National Institute of Environmental Health Sciences and the American
Institute for Cancer Research.
Green Tea products
here!
This article is courtesy
of StrongHealth
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