Thiosemicarbazonate complexes with affinity for amyloid-β fibers: synthesis, characterization and biological studies.

Obtain radioimages of amyloid-β fibers using Tc-complexes. Tridentate thiosemicarbazone and thiocarbonohydrazone ligands containing fragments (stilbene, azobenzene, benzothiazole or benzoxazole) with affinity for amyloid-ß fibers and its Re(I) complexes have been prepared. The molecular structures of several ligands and complexes were determined by x-ray diffraction. Binding affinity studies toward Aß fibers were performed for the ligands and Re(I) complexes. The ability of formation of some Tc(I) complexes, their biodistribution and stability have been established. Complexes of stilbene and benzothiazole thiosemicarbazonates show similar affinity for amyloid-β fibers to the free ligand. These Tc complexes present a reasonable stability and a low capability to cross the blood-brain barrier although not sufficient to brain amyloid imaging.