Inhibition of toxic IAPP amyloid by extracts of common fruits

Abstract

The aggregation of the 37-amino acid polypeptide islet amyloid polypeptide (IAPP, amylin), as either insoluble amyloid or as small oligomers, appears to play a direct role in the death of pancreatic β-islet cells in type 2 diabetes. It is believed that inhibiting the aggregation of IAPP may slow down, if not prevent entirely, the progression of this disease. Extracts of 13 different common fruits were analyzed for their ability to prevent the aggregation of amyloidogenic IAPP. Thioflavin T binding, immuno-detection and circular dichroism assays were performed to test the in vitro inhibitory potential of each extract. Atomic force microscopy was used to visualize the formation of amyloid fibrils with and without each fruit extract. Finally, extracts were tested for their ability to protect living mammalian cells from the toxic effects of amyloid IAPP. Several fruits showed substantial ability to inhibit IAPP aggregation and protect living cells from toxic IAPP amyloid.