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CHICAGO, Aug 29 (Reuters Health) - Numerous studies have
suggested that regular consumption of black tea is protective against a host of human cancers.
Now scientists think they know why.
Black tea's 'secret weapon' may be a compound called
theaflavin-3'-monogallate (TF-2), one of a family of potent anti-cancer compounds called polyphenols.
TF-2 "shows very interesting properties" against colon
cancer cells, according to researcher Dr. Kuang Yu Chen of Rutgers University in New Brunswick, New Jersey.
Speaking here Wednesday to reporters at the annual meeting
of the American Chemical Society, Chen explained that while exposure to TF-2 leaves normal cells unharmed,
cancer cells "commit suicide" in droves.
In laboratory experiments, Chen's team added tea-derived
TF-2 to both healthy cells and colorectal cancer cells. Normal cells flourished, the researchers report,
while malignant cells underwent a process called apoptosis -- programmed cell death.
Investigating further, the Rutgers team discovered that
TF-2 appears to suppress the activity of the Cox 2 gene. This gene has been the focus of intense
scientific research because, when 'switched on,' Cox 2 helps triggers the inflammation process,
an integral part of the sequence of events that can cause normal cells to turn into cancer cells.
"The relation between Cox 2 and colon cancer has been very well established," Chen said.
Popular new drugs such as Vioxx and Celebrex, used to
treat arthritis, also suppress Cox 2. So while pharmaceutical companies race to find complex agents
that inhibit Cox 2, Chen believes one such source -- black tea -- may be found percolating in their
corporate lunchrooms.
Many questions remain to be answered, however. Scientists
have not yet determined the optimum level of black tea consumption needed before any significant anti-cancer
benefit kicks in. And Chen stressed that his findings regarding TF-2 remain preliminary, requiring further
study in animal and human models.
Polyphenols are found in other foods and drink, including
green tea and grape skins, but polyphenols in both those foods exhibit a "less dramatic" effect against
cancer cells, according to the researchers.
However, by modifying the chemical structure of grape skin
polyphenols in the lab, the investigators were able to greatly enhance their toxicity against cancer cells.
Based on that finding, Chen speculates that "by rationally modifying the chemical structure of nutraceuticals
(like grape skin polyphenols) we can actually improve on nature."
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