Interaction studies of oxindole-derivatives with β-amyloid peptides inhibiting its aggregation induced by metal ions

• Published in: Journal of inorganic biochemistry Vol. 245; p. 112227
• Main Authors: Wegermann, Camila Anchau, Pirota, Valentina, Monzani, Enrico, Casella, Luigi, Costa, Luiz Antônio Sodré, Novato, Willian Tássio Gomes, Machini, M. Teresa, da Costa Ferreira, Ana Maria
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.08.2023
• Subjects: Alzheimer Disease - metabolism; Amyloid beta-Peptides - chemistry; Amyloid peptides; Binding constants; Copper - chemistry; Humans; Ions; Isatin; Ligands; Metal complexes; Metals; Oxindole-derived hydrazones; Oxindoles; Oxindolimines; Peptide aggregation inhibition; Peptide Fragments - chemistry; Zinc - chemistry; PBS; AChE; AD; DMSO; Oxindole-derived hydrazones; Oxindolimines; MeCN; isapn; Peptide aggregation inhibition; PDB; Aβ; DFT; isahpy; misapn; HEPES; Binding constants; IC50; ROS; Amyloid peptides; isahim; Metal complexes
• ISSN: 0162-0134; 1873-3344
• DOI: 10.1016/j.jinorgbio.2023.112227

Some hydrazones and Schiff bases derived from isatin, an endogenous oxindole formed in the metabolism of tryptophan, were obtained to investigate their effects on in vitro aggregation of β-amyloid peptides (Aβ), macromolecules implicated in Alzheimer's disease. Some hydrazone ligands, prepared by condensation reactions of isatin with hydrazine derivatives, showed a large affinity binding to the synthetic peptides Aβ, particularly to Aβ1–16. Measurements by NMR spectroscopy indicated that those interactions occur mainly at the metal binding site of the peptide, involving His6, His13, and His14 residues, and that hydrazone E-diastereoisomer interacts preferentially with the amyloid peptides. Experimental results were consistent with simulations using a docking approach, where it is demonstrated that the amino acid residues Glu3, His6, His13, and His14 are those that mostly interact with the ligands. Further, these oxindole-derived ligands can efficiently chelate copper(II) and zinc(II) ions, forming moderate stable [ML] 1:1 species. The corresponding formation constants were determined by UV/Vis spectroscopy, by titrations of the ligands with increasing amounts of metal salts, and the obtained log K values were in the range 2.74 to 5.11. Both properties, good affinity for amyloid peptides, and reasonably good capacity of chelating biometal ions, like copper and zinc, can explain the efficient inhibition of Aβ fragments aggregation, as shown by experiments carried out with the oxindole derivatives in the presence of metal ions. Synopsis: Some hydrazones and Schiff bases derived from an endogenous oxindole were obtained, and investigated about their effects on in vitro aggregation of β-amyloid peptides (Aβ), implicated in Alzheimer's disease. [Display omitted] •Schiff base and hydrazine-derivatives of isatin were synthesized.•These ligands form stable copper and zinc complexes characterized spectroscopically.•Strong interactions of a hydrazine-derivative with amyloid peptide were verified.•Interactions occur mainly through histine residues, involving E-diastereoisomer.•Noteworthy peptide aggregation inhibition was shown in the presence of such ligands.