Discovery and Structure Activity Relationship of Small Molecule Inhibitors of Toxic β-Amyloid-42 Fibril Formation

Heiko Kroth,Annalisa Ansaloni,Luitgard Nagel-Steger,Nampally Sreenivasachary,Hilal A Lashuel,Markus Zweckstetter,Yvan Varisco,Wolfgang Froestl,Dieter Willbold,Paolo Paganetti,Oskar Adolfsson,Andreas Muhs,Valérie Giriens,Maria Pihlgren,Andrea Pfeifer,Sophie Lohmann,Asad Jan,Thomas Schräder ,Nasrollah Rezaei‐Ghaleh ,Maria Pilar López‐Deber

doi:10.1074/jbc.m112.357665

Abstract

Increasing evidence implicates Aβ peptides self-assembly and fibril formation as crucial events in the pathogenesis of Alzheimer disease. Thus, inhibiting Aβ aggregation, among others, has emerged as a potential therapeutic intervention for this disorder. Herein, we employed 3-aminopyrazole as a key fragment in our design of non-dye compounds capable of interacting with Aβ42 via a donor-acceptor-donor hydrogen bond pattern complementary to that of the β-sheet conformation of Aβ42. The initial design of the compounds was based on connecting two 3-aminopyrazole moieties via a linker to identify suitable scaffold molecules. Additional aryl substitutions on the two 3-aminopyrazole moieties were also explored to enhance π-π stacking/hydrophobic interactions with amino acids of Aβ42. The efficacy of these compounds on inhibiting Aβ fibril formation and toxicity in vitro was assessed using a combination of biophysical techniques and viability assays. Using structure activity relationship data from the in vitro assays, we identified compounds capable of preventing pathological self-assembly of Aβ42 leading to decreased cell toxicity.

Highlights

Self-aggregation of ␤-amyloid plays an important role in the pathogenesis of Alzheimer disease
Using structure activity relationship data from the in vitro assays, we identified compounds capable of preventing pathological self-assembly of A␤1– 42 peptide (A␤42) leading to decreased cell toxicity
Screening for Inhibitors of Fibril Formation Using Thioflavin T (ThT) Assays—We first investigated the effect of our compounds (Fig. 1B) on the aggregation and fibril formation of A␤42 by the mean of different ThT fluorescent assays [43]

Summary

Introduction

Self-aggregation of ␤-amyloid plays an important role in the pathogenesis of Alzheimer disease. Results: Small molecule inhibitors of ␤-amyloid fibril formation reduce ␤-amyloid mediated cell toxicity. Increasing evidence implicates A␤ peptides self-assembly and fibril formation as crucial events in the pathogenesis of Alzheimer disease. Additional aryl substitutions on the two 3-aminopyrazole moieties were explored to enhance ␲-␲ stacking/hydrophobic interactions with amino acids of A␤42. The efficacy of these compounds on inhibiting A␤ fibril formation and toxicity in vitro was assessed using a combination of biophysical techniques and viability assays. Using structure activity relationship data from the in vitro assays, we identified compounds capable of preventing pathological self-assembly of A␤42 leading to decreased cell toxicity

Objectives

Results

Conclusion