Natural polyphenols binding to amyloid: a broad class of compounds to treat different human amyloid diseases

Polyphenols are a large group of phytonutrients found in herbal beverages and foods. They have manifold biological activities, including antioxidative, antimicrobial, and anti-inflammatory properties. Interestingly, some polyphenols bind to amyloid and substantially ameliorate amyloid diseases. Misfolding, aggregation, and accumulation of amyloid fibrils in tissues or organs leads to a group of disorders, called amyloidoses. Prominent diseases are Alzheimer's, Parkinson's, and Huntington's disease, but there are other, less well-known diseases wherein accumulation of misfolded protein is a prominent feature. Amyloidoses are a major burden to public health. In particular, Alzheimer's disease shows a strong increase in patient numbers. Accelerated development of effective therapies for amyloidoses is a necessity. A viable strategy can be the prevention or reduction of protein misfolding, thus reducing amyloid build-up by restoring the cellular aggretome. Amyloid-binding polyphenols affect amyloid formation on various levels, e.g. by inhibiting fibril formation or steering oligomer formation into unstructured, nontoxic pathways. Consequently, preclinical studies demonstrate reduction of amyloid-formation by polyphenols. Amyloid-binding polyphenols might be suitable lead structures for development of imaging agents for early detection of disease and monitoring amyloid deposition. Intake of dietary polyphenols might be relevant to the prevention of amyloidoses. Nutraceutical strategies might be a way to reduce amyloid diseases.