A Comparative Study of the Effects of Platinum (II) Complexes on β-Amyloid Aggregation: Potential Neurodrug Applications

Abstract

Herein the effects of three platinum complexes, namely (SP-4-2)-(2,2′-bipyridine)dichloridoplatinum(II), Pt-bpy, (SP-4-2)-dichlorido(1,10-phenanthroline) platinum(II), Pt-phen, and (SP-4-2)-chlorido(2,2′:6′,2′′-terpyridine)platinum(II) chloride, Pt-terpy, on the aggregation of an amyloid model system derived from the C-terminal domain of Aβ peptide (Aβ21–40) were investigated. Thioflavin T (ThT) binding assays revealed the ability of Pt(II) compounds to repress amyloid aggregation in a dose-dependent way, whereas the ability of Aβ21–40 peptide to interfere with ligand field of metal complexes was analyzed through UV-Vis absorption spectroscopy and electrospray ionization mass spectrometry. Spectroscopic data provided micromolar EC50 values and allowed to assess that the observed inhibition of amyloid aggregation is due to the formation of adducts between Aβ21–40 peptide and complexes upon the release of labile ligands as chloride and that they can explore different modes of coordination toward Aβ21–40 with respect to the entire Aβ1–40 polypeptide. In addition, conformational studies through circular dichroism (CD) spectroscopy suggested that Pt-terpy induces soluble β-structures of monomeric Aβ21–40, thus limiting self-recognition. Noticeably, Pt-terpy demonstrated the ability to reduce the cytotoxicity of amyloid peptide in human SH-SY5Y neuroblastoma cells. Presented data corroborate the hypothesis to enlarge the application field of already known metal-based agents to neurodegenerative diseases, as potential neurodrugs.