Inhibition of Human Amylin Aggregation: In Silico and In Vitro Studies

Human islet amyloid polypeptide (hIAPP), also termed amylin, is an endocrine hormone that plays a key role in regulating blood glucose levels. Pathological conformational changes in amylin can lead to its aggregation into amyloid deposits, which are significant markers in the development of type 2 diabetes (T2D) and Alzheimer's disease (AD). In this study, we explored 1-benzylamino-2-hydroxyalkyl derivatives as potential amylin aggregation inhibitors. These compounds have previously demonstrated activity against amyloid-β aggregation in AD. We conducted ThT and DLS assays to identify compounds 18 and 22 as the most active derivatives, inhibiting amylin aggregation with IC₅₀ values of 3.04 and 2.71 μM, respectively. These compounds preserved small-sized oligomers, which exhibited reduced cytotoxicity compared to controls. The fluorescence quenching assay revealed that compounds 18 and 22 significantly quenched the intrinsic fluorescence of amylin without altering the emission spectra, indicating conformational changes without major modifications in the Tyr37 region. Binding and thermodynamic analyses indicated strong, spontaneous interactions dominated by hydrophobic forces. An in silico study compared the behavior of compound 18 (the most potent) and compound 9 (the least potent) in the ThT assay. Overall, compound 18 formed more interactions with amylin than compound 9 and remained attached to the peptide for a longer time during the simulation, more frequently stabilizing the α-helical fragments. This stabilization may help delay the transition into intermediate structures associated with amyloidogenic β-sheet formation. Our findings offer new insights into the aggregation process and may inform the design of more effective aggregation inhibitors.