Inhibition of HEWL fibril formation by taxifolin: Mechanism of action

PLoS One. 2017 Nov 13;12(11):e0187841. doi: 10.1371/journal.pone.0187841. eCollection 2017.

Abstract

Among therapeutic approaches for amyloid-related diseases, attention has recently turned to the use of natural products as effective anti-aggregation compounds. Although a wealth of in vitro and in vivo evidence indicates some common inhibitory activity of these compounds, they don't generally suggest the same mechanism of action. Here, we show that taxifolin, a ubiquitous bioactive constituent of foods and herbs, inhibits formation of HEWL amyloid fibrils and their related toxicity by causing formation of very large globular, chain-like aggregates. A range of amyloid-specific techniques were employed to characterize this process. We found that taxifolin exerts its effect by binding to HEWL prefibrillar species, rather than by stabilizing the molecule in its native-like state. Furthermore, it's binding results in diverting the amyloid pathway toward formation of very large globular, chain-like aggregates with low β-sheet content and reduced solvent-exposed hydrophobic patches. ThT fluorescence measurements show that the binding capacity of taxifolin is significantly reduced, upon generation of large protofibrillar aggregates at the end of growth phase. We believe these results may help design promising inhibitors of protein aggregation for amyloid-related diseases.

MeSH terms

  • Binding Sites
  • Cell Line
  • Circular Dichroism
  • Electrophoresis, Polyacrylamide Gel
  • Humans
  • Hydrophobic and Hydrophilic Interactions
  • Microscopy, Atomic Force
  • Molecular Docking Simulation
  • Neurofibrils / drug effects*
  • Neurofibrils / metabolism
  • Quercetin / analogs & derivatives*
  • Quercetin / metabolism
  • Quercetin / pharmacology
  • Spectrometry, Fluorescence
  • Spectrophotometry, Ultraviolet

Substances

  • Quercetin
  • taxifolin

Grants and funding

This work was supported by grants from the Research Council of the Institute for Advanced Studies in Basic Sciences (IASBS), Zanjan, Iran.