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Green tea epigallocatechin-3-gallate (EGCG) modulates amyloid precursor protein cleavage and reduces cerebral amyloidosis in Alzheimer transgenic mice.

Rezai-Zadeh K, Shytle D, Sun N, Mori T, Hou H, Jeanniton D, Ehrhart J, Townsend K, Zeng J, Morgan D, Hardy J, Town T, Tan J

Silver Child Development Center, Department of Psychiatry and Behavioral Medicine, University of South Florida, Tampa, Florida 33613, USA.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder pathologically characterized by deposition of beta-amyloid (Abeta) peptides as senile plaques in the brain. Recent studies suggest that green tea flavonoids may be used for the prevention and treatment of a variety of neurodegenerative diseases. Here, we report that (-)-epigallocatechin-3-gallate (EGCG), the main polyphenolic constituent of green tea, reduces Abeta generation in both murine neuron-like cells (N2a) transfected with the human "Swedish" mutant amyloid precursor protein (APP) and in primary neurons derived from Swedish mutant APP-overexpressing mice (Tg APPsw line 2576). In concert with these observations, we find that EGCG markedly promotes cleavage of the alpha-C-terminal fragment of APP and elevates the N-terminal APP cleavage product, soluble APP-alpha. These cleavage events are associated with elevated alpha-secretase activity and enhanced hydrolysis of tumor necrosis factor alpha-converting enzyme, a primary candidate alpha-secretase. As a validation of these findings in vivo, we treated Tg APPsw transgenic mice overproducing Abeta with EGCG and found decreased Abeta levels and plaques associated with promotion of the nonamyloidogenic alpha-secretase proteolytic pathway. These data raise the possibility that EGCG dietary supplementation may provide effective prophylaxis for AD.

Published 22 September 2005 in J Neurosci, 25(38): 8807-14.
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