Pomegranate peel, chokeberry leaves and Ironwort extract as novel natural inhibitors of amylin aggregation and cellular toxicity in pancreatic β cells.

Impeding or reducing human amylin aggregation and/or its toxicity can be key to preventing pancreatic islet amyloidosis and β-cell loss in patients with Type 2 Diabetes Mellitus (T2DM). Here, Punica granatum (pomegranate) peel, Sideritis raeseri (ironwort) and Aronia melanocarpa (chokeberry) leaf extracts, were tested for their novel anti-aggregative and antitoxic properties in human amylin (hIAPP) treated rat pancreatic insulinoma (INS) cells. The protein aggregation (Th-T) assay revealed an inhibitory trend of all three plant extracts against amylin aggregates. In agreement with this finding, pomegranate peel and ironwort extracts effectively prevented the transition of hIAPP from disordered, random coil structures into aggregation prone β-sheet enriched molecular assemblies, revealed by CD spectroscopy. Consistent with their anti-aggregative action, all three extracts prevented, to various degrees, reactive oxygen species (ROS) accumulation, mitochondrial stress, and, ultimately, apoptosis of INS cells. Collectively, the results from this study demonstrate effectiveness of natural products to halt hIAPP aggregation, redox stress, and toxicity, which could be exploited as novel therapeutics against amylin-derived islet amyloidosis and β-cell stress in T2DM.