ABSTRACT
In peptidotriazolamers every second peptide bond is replaced by a 1H-1,2,3-triazole. Such foldamers are expected to bridge the gap in molecular weight between small-molecule drugs and protein-based drugs. Amyloid ß (Aß) aggregates play an important role in Alzheimer's disease. We studied the impact of amide bond replacements by 1,4-disubstituted 1H-1,2,3-triazoles on the inhibitory activity of the aggregation "hot spots" K16 LVFF20 and G39 VVIA42 in Aß(1-42). We found that peptidotriazolamers act as modulators of the Aß(1-42) oligomerization. Some peptidotriazolamers are able to interfere with the formation of toxic early Aß oligomers, depending on the position of the triazoles, which is also supported by computational studies. Preliminary inâ vitro results demonstrate that a highly active peptidotriazolamer is also able to cross the blood-brain-barrier.
Subject(s)
Alzheimer Disease/metabolism , Amyloid beta-Peptides/chemistry , Blood-Brain Barrier/metabolism , Peptide Fragments/chemistry , Peptides/chemistry , Protein Aggregates/drug effects , Triazoles/chemistry , Amides/metabolism , Amyloid beta-Peptides/metabolism , Cell Survival , Humans , Models, Biological , Models, Molecular , Molecular Conformation , Molecular Structure , Peptide Fragments/metabolism , Protein Binding , Structure-Activity Relationship , Triazoles/metabolismABSTRACT
Misfolding and aggregation of amyloid ß1-42 peptide (Aß1-42) play a central role in the pathogenesis of Alzheimer's disease (AD). Targeting the highly cytotoxic oligomeric species formed during the early stages of the aggregation process represents a promising therapeutic strategy to reduce the toxicity associated with Aß1-42. Currently, the thioflavinâ T (ThT) assay is the only established spectrofluorometric method to screen aggregation inhibitors. The success of the ThT assay is that it can detect Aß1-42 aggregates with high ß-sheet content, such as protofibrils or fibrils, which appear in the late aggregation steps. Unfortunately, by using the ThT assay, the detection of inhibitors of early soluble oligomers that present a low ß-sheet character is challenging. Herein, a new, facile, and robust boron-dipyrromethene (BODIPY) real-time assay suitable for 96-well plate format, which allows screening of compounds as selective inhibitors of the formation of Aß1-42 oligomers, is reported. These inhibitors decrease the cellular toxicity of Aß1-42, although they fail in the ThT assay. The findings have been confirmed and validated by structural analysis and cell viability assays under comparable experimental conditions. It is demonstrated that the BODIPY assay is a convenient method to screen and discover new candidate compounds that slow down or stop the pathological early oligomerization process and are active in the cellular assay. Therefore, it is a suitable complementary screening method of the current ThT assay.
Subject(s)
Amyloid beta-Peptides/antagonists & inhibitors , Amyloid beta-Peptides/metabolism , Boron Compounds/metabolism , Drug Monitoring/methods , High-Throughput Screening Assays/methods , Neuroprotective Agents/pharmacology , Peptide Fragments/antagonists & inhibitors , Peptide Fragments/metabolism , Small Molecule Libraries/pharmacology , HumansABSTRACT
The unstable dithiocarboxylic acids dithioacetic acid, 2-methyl-dithiopropionic acid, 2,2-dimethyl-dithiopropionic acid and dithiobenzoic acid were synthesized and characterized by NMR spectroscopy and GC/MS. The stable dithiocarboxylic acids 2,4,6-trimethyl benzoic acid, 2,4,6-tri-iso-propylbenzoic acid and 2,6-dimesityl benzoic acid were synthesized, isolated and characterized by spectroscopic methods and in parts by mass spectrometry and X-ray crystallography. The new data were used to re-evaluate literature data on the synthesis, spectroscopy and structural data of dithiocarboxylic acids as a fundamental class of organic compounds in general.
