A chemical abundant in red wine may reduce the level of a harmful peptide known to cause brain plaques associated with Alzheimer's disease, new research has found. The study authors caution, however, that achieving that effect in humans is likely to be more complicated than simply drinking in moderation.
The research, published in the Nov. 11 issue of the Journal of Biological Chemistry, found that the compound, resveratrol, reduced levels of the harmful peptide in brain-cell samples by more than half in some instances, compared with untreated samples.
Light to moderate drinking has been linked to a lower rate of Alzheimer's disease in the elderly, and drinking wine in particular was found to reduce the risk of dementia in a Danish study and other European research.
The authors of the current study--headed by Philippe Marambaud, a researcher at the Litwin-Zucker Research Center for the Study of Alzheimer's Disease and Memory Disorders in Manhasset, N.Y.--suspected that moderate wine intake may reduce Alzheimer's risk due to the antioxidant and neuroprotective properties of resveratrol. The polyphenol naturally occurs in abundance in grapes, berries, peanuts and other foods. Resveratrol has been found in previous studies to hold the potential to do everything from contribute to lower cholesterol levels, alleviate some lung diseases, fight certain types of cancer, reduce the growth of skin melanomas and damage caused by sunburn and extend the longevity of some basic organisms.
To see if resveratrol may affect Alzheimer's disease, the team obtained samples of mice brain cells to which amyloid-beta peptides had been added. These strings of proteins are associated with the formation of "senile plaques," a known risk factor for Alzheimer's. The peptides bond with areas of dead nerve cells in the brain, and when these plaques form into clumps, they interfere with normal cognitive communication.
Marambaud and his team exposed the cell samples, except for a control group, to different types of wine compounds--including resveratrol, quercetin and catechin--in amounts ranging from 10 micromolars (a measure of a substance's concentration in solution) to 40 micromolars.
After 48 hours of exposure to resveratrol, the levels of amyloid-beta peptides began to drop significantly; the greater the concentration of resveratrol, the greater the drop in the peptides. For example, while the control group had 8 nanograms per milliliter of amyloid-beta peptides at 48 hours, there were 7 ng/ml of the peptides in the 10 micromolar solution. The 40 micromolar solution proved the most effective, reducing the peptides by more than half, to 3 ng/ml, after 48 hours. The other compounds were comparatively ineffective at reducing the amount of peptides.
Marambaud said his team observed that resveratrol did not inhibit the proliferation of the amyloid-beta peptides, but instead seemed to break up the protein strings. While the researchers are not certain exactly how this happens, they believe resveratrol may stimulate the activity of proteasome, another protein complex that can digest proteins into shorter peptides and amino acids, which are easier for the body to clear from the brain.
Marambaud said that the findings suggest that one day a resveratrol-based product could be produced to fight not only Alzheimer's but other degenerative diseases such as Parkinson's and Huntington's. But he warned that drinking wine may not yield a similar benefit inside the human brain, as it is unclear how well the body metabolizes resveratrol. The next step, he said, is more research, using live mice and more potent, more stable versions of resveratrol.
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