Inhibition of the Self-Assembly of Aβ and of Tau by Polyphenols: Mechanistic Studies

The amyloid-beta (A beta) peptide and tau protein are thought to play key neuropathogenic roles in Alzheimer's disease (AD). Both A beta and tau self-assemble to form the two major pathological hallmarks of AD: amyloid plaques and neurofibrillary tangles, respectively. In this review, we show that naturally occurring polyphenols abundant in fruits, vegetables, red wine, and tea possess the ability to target pathways associated with the formation of assemblies of A beta and tau. Polyphenols modulate the enzymatic processing of the amyloid-beta precursor protein and inhibit toxic A beta oligomerization by enhancing the clearance of A beta 42 monomer, modulating monomer-monomer interactions and remodeling oligomers to non-toxic forms. Additionally, polyphenols modulate tau hyperphosphorylation and inhibit tau beta-sheet formation. The anti-A beta-self-assembly and anti-tau-self-assembly effects of polyphenols increase their potential as preventive or therapeutic agents against AD, a complex disease that involves many pathological mechanisms.