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

Herein the effects of three platinum complexes, namely (-4-2)-(2,2'-bipyridine)dichloridoplatinum(II), Pt-bpy, (-4-2)-dichlorido(1,10-phenanthroline) platinum(II), Pt-phen, and (-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 (Aβ) 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 Aβ 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 EC values and allowed to assess that the observed inhibition of amyloid aggregation is due to the formation of adducts between Aβ peptide and complexes upon the release of labile ligands as chloride and that they can explore different modes of coordination toward Aβ with respect to the entire Aβ polypeptide. In addition, conformational studies through circular dichroism (CD) spectroscopy suggested that Pt-terpy induces soluble β-structures of monomeric Aβ, 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.