Mechanisms of Regulation of Amyloid-Induced Permeability of Model Lipid Membranes by Polyphenols

Abstract

This work is devoted to the study of the processes of formation and functioning of ion channels by amyloidogenic peptides, pathological aggregation and accumulation of which is a cause of neurodegenerative disorders. The effect of the plant polyphenols phloretin, butein, resveratrol, isoliquiritigenin, 4'-hydroxychalcone, and cardamonine on the pore-forming activity of β-amyloid peptide fragment 25–35 in bilayer lipid membranes from palmitoyl-phosphocholine was studied. It was demonstrated that the introduction of phloretin, butein or isoliquiritigenin in membrane-bathing solutions to a concentration of 20 µM leads to the increase of macroscopic transmembrane currents induced by peptide. At the same time, cardamonine, 4'-hydroxychalcone, and resveratrol have no effect on the activity of β-amyloid peptide fragment 25–35. The comparison of the results of studying the effect of tested polyphenols on electric and elastic properties of model membranes and pore-forming ability of β-amyloid peptide fragment 25–35 allowed it to concluded that there is no connection between the potentiating effect of phloretin, butein, or isoliquiritigenin and changes in the physicochemical properties of lipid bilayers. Results obtained by means of a confocal fluorescent microscopy indicate that the domain organization of the lipid bilayer may play a role in the pore-forming activity of amyloidogenic peptide. The results of electrophysiological measurements obtained for α-synuclein (another protein forming ion-permeable pores) do not contradict the hypothesis of binding of polyphenols, hydroxylated in the 7 position of the A cycle and in the 4'-position of the B cycle, with an open propane fragment with β-layers formed by amyloid peptides.