Biophenols pharmacology against the amyloidogenic activity in Alzheimer's disease

Alzheimer's disease characterized by misfolding, aggregation, and accumulation of amyloid fibrils in an insoluble form in the brain, is often known as amyloidosis. The process of aggregation follows a mechanism of seeded polymerization. For decades, a great number of failures in Alzheimer's disease (AD) drug development, with both small molecules and immunotherapies failing to establish a drug/placebo difference or having an unacceptable toxicity have led to the therapeutic research interest towards a group of anti-amyloidogenic compounds originated from plants called biophenols. A number of in vitro and in vivo studies have demonstrated that the plant biophenols bind with amyloid beta (Aβ) toxic oligomers and reducing the fibril formation and toxicity. The exact mechanism of biophenols action against Aβ toxicity is unknown, while studies have suggested the amyloid-binding affinity of biophenols affecting Aβ on various levels, e.g. by direct inhibiting fibril formation or steering oligomer formation into unstructured, inhibiting Aβ aggregation, and promoting nontoxic pathways. Furthermore, biophenols involved in the inhibition of Aβ progression (e.g., oxidative stress and neuroinflammation) and effecting the amyloid precursor protein processing through the direct or indirect inhibition of β-secretase (BACE-1), γ-secretase and/or activation of α-secretase. This critical review account for the biophenols as magic bullet targeting against Aβ, and simulation the results on how biophenols interact with the Aβ monomers and oligomers, highly desirable knowledge for predicting new efficient nutraceutical drugs.