A natural polyphenol found in green tea may help prevent heart attacks and strokes. The polyphenol, epigallocatechin-3-gallate (EGCG), is known to have antioxidant properties, and it is already an ingredient in health-promoting supplements. But now the polyphenol is being investigated for its plaque-busting abilities. According to a new study, EGCG can break up and dissolve potentially dangerous protein plaques found in blood vessels.
The new study was led by scientists based at Lancaster University and the University of Leeds. According to these scientists, EGCG may work with heparin to remodel apolipoprotein A-1 (ApoA-1), a protein that can form amyloid deposits, so that it may dissolve more readily.
Detailed findings appeared May 31 in the Journal of Biological Chemistry, in an article entitled “Epigallocatechin-3-Gallate Remodels Apolipoprotein A-I Amyloid Fibrils into Soluble Oligomers in the Presence of Heparin.”
“EGCG selectively increased the mobility of specific backbone and side-chain sites of apoA-I fibrils formed in the absence of heparin, but the fibrils largely retained their original morphology and remained insoluble,” wrote the article’s authors. “By contrast, fibrils formed in the presence of heparin were mobilized extensively by the addition of equimolar EGCG, and the fibrils were remodeled into soluble 20-nm-diameter oligomers with a largely α-helical structure that were nontoxic to human umbilical artery endothelial cells.”
Essentially, the researchers found that in the presence of heparin, EGCG binds to amyloid fibers of ApoA-1, converting them to smaller soluble molecules that are less likely to be damaging to blood vessels.
Now, the researchers are working on finding ways of introducing effective amounts of EGCG into the bloodstream without it being necessary to drink large and potentially harmful quantities of green tea. This could involve modifying the chemical structure of EGCG, making it easier to be absorbed from the stomach and more resistant to metabolism, or developing new methods to deliver the molecule to the plaques—such as via an injection.
"The health benefits of green tea have been widely promoted and it has been known for some time that EGCG can alter the structures of amyloid plaques associated with Alzheimer's disease,” said David Middleton, professor in chemistry at Lancaster University. "Our results show that this intriguing compound might also be effective against the types of plaques which can cause heart attacks and strokes."
The researchers note that additional work will be needed to develop a usable form of EGCG. The compound is readily broken down by the body, so merely drinking EGCG-rich green tea is unlikely to improve heart health. Going forward, researchers may derive useful information if they continue studying how EGCG works. The current study, the researchers indicated, suggests that EGCG-induced remodeling of amyloid may be tightly regulated by glycosaminoglycan polysaccharides that colocalize with amyloid in vivo.