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| A new study investigating the effects of the major flavonoid component of green
tea on hepatic steatosis (fatty liver) found that it significantly protected
livers that suffered ischemia/reperfusion (I/R) injury in mice. I/R injury,
which is caused by decreased blood flow, can lead to complications after liver
transplantation.
The results of this study appear in the March 2005 issue of Liver
Transplantation, the official journal of the American Association for the Study
of Liver Diseases (AASLD) and the International Liver Transplantation Society
(ILTS). The journal is published on behalf of the societies by John Wiley &
Sons, Inc. and is available online via Wiley InterScience at
http://www.interscience.wiley.com/j...ransplantation.
Approximately one-fifth of the U.S. population is afflicted with hepatic
steatosis due to a rising incidence of obesity. Because fatty livers are more
sensitive than lean livers to I/R injury and are associated with an increased
risk of disease and death, this has resulted in fewer usable donors for liver
transplants. In fact, nearly one-third of all donated livers are afflicted with
fatty changes, but longer waiting lists are forcing practitioners to consider
using these organs. A previous study found that rinsing livers with a solution
containing green tea extract prevented failures in transplants using fatty
livers. The current study examined whether (-)-epigallocatechin-3-gallate
(EGCG), the major flavonoid component found in green tea, protected fatty livers
from cell damage after I/R injury.
Led by Kenneth D. Chavin, M.D., Ph.D., of the Medical university of South
Carolina in Charleston, SC, researchers administered EGCG either orally or by
injection and performed surgery to induce I/R injury in mice; control groups did
not receive the EGCG. Mice receiving EGCG by either method showed a survival
rate of 100 percent, versus 65 percent for the controls. Tissue analysis showed
that the EGCG mice had decreased necrosis (cell death) and a higher percentage
of viable tissue, demonstrating that the flavonoid protected the liver from I/R
injury.
The next step was to determine the mechanism by which EGCG protected fatty liver
cells from I/R injury. Researchers developed a technique to measure fatty acids
and found that levels of palmitic and linoleic acid, two fatty acids that are
present in large amounts in fatty livers, decreased significantly in EGCG
treated mice. Further tests revealed an increase in hepatic energy stores (one
of the liver's functions is to store energy in the form of glycogen) in EGCG
mice and showed that EGCG was acting as an antioxidant, thereby protecting fatty
livers from I/R injury. In addition, the study showed that EGCG reduced liver
fat content by approximately 55 percent. "Significant differences to the fat
content, energy stores and markers of cellular injury were observed regardless
of how the compound was administered," the authors note.
The authors conclude that "the data presented here indicates that EGCG protects
the steatotic liver from I/R injury by reducing hepatic fat content, increasing
energy stores, serving as an antioxidant and may stimulate the production of
additional antioxidants such as GSH." They add that these activities warrant
further investigation and that a thorough understanding of how ECGC acts may
suggest its use as a therapeutic agent for fatty livers used in liver
transplants.
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Article: "Short-Term Administration of (-)-Epigallocatechin Gallate Reduces
Hepatic Steatosis and Protects Against Warm Hepatic Ischemia/Reperfusion Injury
in Steatotic Mice," Ryan N. Fiorini, Jennifer Donovan, David Rodwell, Zachary
Evans, Gang Cheng, Harold May, Charles E. Milliken, John Markowitz, Crystal
Campbell, Julia K. Haines, Michael G. Schmidt, Kenneth D. Chavin, Liver
Transplantation, 11:3; March 2005 (DOI: 10.1002/lt.20348).
Alan
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