Written by Susan Sweeny Johnson, PhD, Biochem. Flavonoids in green tea slowed the development of a marker for Huntington’s disease.
Huntington’s is an inherited, progressive neurodegenerative disease that affects 8 in every 100,000 people. Symptoms, which do not appear until the disease is well established, include jerky movements, inability to show facial emotion, poor swallowing and selective mental dysfunctions.
The gene that causes Huntington’s is mutated such that the resultant protein, called huntingtin, has a section of glutamine amino acids in a row. In a recent study, researchers screened about 5,000 natural products for their ability to slow clumping of this protein. They were looking for something that was known to be non-toxic when ingested over long periods of time, was small enough to pass the blood brain barrier, and already was shown to have a beneficial effect on other neurological diseases. They especially looked at flavonoids such as EGCG found in green tea which have well established antioxidant properties and slow the progression of Alzheimer’s and Parkinson’s diseases. (1)
EGCG, and to a lesser extent its cousin GCG, significantly slowed the clumping of the huntingtin protein in vitro (in a test tube).The more EGCG present, the longer it took for clumping to occur. It should be noted that different larger sized clumps were eventually formed in the presence of EGCG. The quantity of protein in these clumps was much lower than that formed without EGCG and apparently these clumps are not as toxic to the cell.
The effect of EGCG was not due to its antioxidant properties since similar flavonoids with antioxidant properties did not affect protein clumping.
In studies of living things, the researchers also showed that the growth of yeast containing the huntingtin protein is severely retarded but could be induced by adding EGCG. When fruit flies containing the huntintin protein were fed with a solvent control or EGCG, the ability to climb was significantly improved in the EGCG group. The natural degeneration of photoreceptors in their eyes was significantly slowed by ingesting EGCG also.
Since EGCG is well tolerated, is a beneficial antioxidant, passes the blood brain barrier, and is known to be beneficial in other neurological diseases, it appears to be a good candidate for further research.(2)
Source: Ehrnhoefer, Dagmar E., Martin Duennwald, Phoebe Markovic, Jennifer L. Wacker, Sabine Engemann, Margaret Roark, Justin Legleiter et al. “Green tea (−)-epigallocatechin-gallate modulates early events in huntingtin misfolding and reduces toxicity in Huntington’s disease models.” Human molecular genetics 15, no. 18 (2006): 2743-2751.
© The Author 2006. Published by Oxford University Press. All rights reserved.
Posted on August 6, 2008.
References:
- Mandel, S.A., Avramovich-Tirosh, Y., Reznichenko, L., Zheng, H., Weinreb, O., Amit, T. and Youdim, M.B. (2005) Multifunctional activities of green tea catechins in neuroprotection. Modulation of cell survival genes, iron-dependent oxidative stress and PKC signaling pathway. Neurosignals, 14, 46–60
- Henning, S.M., Niu, Y., Lee, N.H., Thames, G.D., Minutti, R.R., Wang, H., Go, V.L. and Heber, D. (2004) Bioavailability and antioxidant activity of tea flavanols after consumption of green tea, black tea, or a green tea extract supplement. Am. J. Clin. Nutr., 80, 1558–1564
