Multifunctional Quinoline-Triazole Derivatives as Potential Modulators of Amyloid-b Peptide Aggregation

Metal ion dyshomeostasis is hypothesized to play a role in the toxicity and aggregation of the amyloid beta (Aβ) peptide, contributing to Alzheimer's disease (AD) pathology. We report on the synthesis andmetal complexation ability of three bidentate quinoline-triazole derivatives 3-(4-(quinolin-2-yl)-1H-1,2,3-triazol-1-yl)propan-1-ol (QOH), 4-(2-(4-(quinolin-2-yl)-1H-1,2,3-triazol-1-yl)ethyl)morpholine (QMorph), and 4-(2-(4-(quinolin-2-yl)-1H-1,2,3-triazol-1-yl)ethyl)thiomorpholine (QTMorph). We further study the utility of these ligands tomodulate Aβ peptide aggregation processes in the presence and absence of Cu2+ions. Ligand-peptide interactions were first investigated using both 2-D 1H-15N band-selective optimized flip angle short transient heteronuclear multiple quantumcorrelation (SOFAST-HMQC) NMR spectroscopy and molecular modeling techniques, indicating interactionswith glutamic acid (E3) and several residues in the hydrophobic region of Aβ. Native gel electrophoresiswith western blotting along with transmission electron microscopy provided information on the ability of each ligand to modulate Aβ aggregation.While the ligands alone did not modify Aβ peptide aggregation at the 24 h timepoint, signifying relatively weak ligand-peptide interactions, the ligands did modify the aggregation profile of the peptide in the presence of stoichiometric and suprastoichiometric Cu. Interestingly, the thioether derivative QTMorph exhibited the most pronounced effect on peptide aggregation in the presence of Cu. Overall, the quinoline-triazole ligand series were shown to interact with the hydrophobic region of the Aβ peptide, and modulate the Cu-Aβ aggregation process.