The accumulation of proteins that cause Huntington's Disease is slowed by Green Tea Extract, epigallocatechin gallate (EGCG), German scientists have reported.

This news adds to a growing body of science on the health benefits of green tea, with consumption linked to a lower risk of certain cancers, increased weight loss, and protection against Alzheimer's.

Huntington's disease, along with Alzheimer's and Parkinson's, belong to the family of neurodegenerative diseases caused by protein misfolding. The incurable disease is hereditary and has a prevalence of 1 in every 15,000 people. In Germany, about 8,000 cases are currently known, in the UK the figure is reported to be about 5,000, and in the US the figure is about 30,000.

The disease is characterized by jerky, uncontrolled movements, an unsteady gait and grimaces leading to its original common name of Huntington's chorea (from the ancient Greek for "dance").

In 1993, scientists discovered the gene that encodes the mutant protein, the so-called huntingtin protein. A mutation in this protein results in elongation of parts of the protein called polyglutamine chains, which cause the overall huntingtin protein to lose its normal structure. These mutant proteins can not be disposed of by the body and accumulate in the brain of sufferers, eventually being toxic to the nerve cells in the brain.

Professor Erich Wanker from the Max Delbrück Center for Molecular Medicine Berlin-Buch (MDC), led the research and looked at the effect on EGCG on the aggregation of these mutant proteins in vitro, and found that the green tea extract could interfere with the very early events of this process.
Lead author, Dagmar Ehrnhoefer wrote, "We demonstrate that the green tea polyphenol epigallocatechin-3-gallate (EGCG) potently inhibits the aggregation of mutant huntingtin protein in a dose-dependent manner."

Professor Wanker's group used laboratory-based experiments to show that the green tea extract inhibited misfolding of the huntingtin protein in vitro, as well as using fruit flies genetically modified to over-express the mutant protein. The latter experiments showed that the degeneration of the flies' photoreceptor and motor function improved.

"These results indicate that modulators of huntingtin misfolding … like EGCG are likely to reduce polyglutamine -mediated toxicity in vivo," concluded Ehrnhoefer.

Green tea is said to contain over four times the concentration of antioxidant catechins than black tea (green tea leaves that have been oxidized by fermentation), about 70 mg catechins per 100 mL compared to 15 mg per 100 mL for black tea.


Human Molecular Genetics, September 2006 (Vol. 15, pp. 2743-2751), Dagmar Ehrnhoefer
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9/8/2006