New mimetic peptides inhibitors of A beta aggregation. Molecular guidance for rational drug design

A new series of mimetic peptides possessing a significant A beta aggregation modulating effect was reported here. These compounds were obtained based on a molecular modelling study which allowed us to perform a structural-based virtual selection. Monitoring A beta aggregation by thioflavin T fluorescence and transmission electron microscopy revealed that fibril formation was significantly decreased upon prolonged incubation in presence of the active compounds. Dot blot analysis suggested a decrease of soluble oligomers strongly associated with cognitive decline in Alzheimer's disease. For the molecular dynamics simulations, we used an A beta(42) pentameric model where the compounds were docked using a blind docking technique. To analyze the dynamic behaviour of the complexes, extensive molecular dynamics simulations were carried out in explicit water. We also measured parameters or descriptors that allowed us to quantify the effect of these compounds as potential inhibitors of A beta aggregation. Thus, significant alterations in the structure of our A beta(42) protofibril model were identified. Among others we observed the destruction of the regular helical twist, the loss of a stabilizing salt bridge and the loss of a stabilizing hydrophobic interaction in the beta 1 region. Our results may be helpful in the structural identification and understanding of the minimum structural requirements for these molecules and might provide a guide in the design of new aggregation modulating ligands. (C) 2015 Elsevier Masson SAS. All rights reserved