853214-50-3Relevant articles and documents
Rhenium and technetium complexes of thioamide derivatives of pyridylhydrazine that bind to amyloid-β plaques
Fletcher, Scott P.,Noor, Asif,Hickey, James L.,McLean, Catriona A.,White, Jonathan M.,Donnelly, Paul S.
, p. 1139 - 1151 (2018)
Abstract: Age-associated deposition of amyloid-β in cerebral blood vessels, a condition referred to as cerebral amyloid angiopathy, can contribute to stroke and dementia. This research aimed to design new radioactive technetium-99?m complexes that bind to amyloid-β plaques that have the potential to assist in diagnosis of cerebral amyloid angiopathy using single-photon-emitted computed tomography (SPECT) imaging. Six new pyridylthiosemicarbazide ligands containing either benzofuran or styrylpyridyl functional groups that are known to selectively bind to amyloid plaques were prepared. Non-radioactive isotopes of technetium are not available so rhenium was used as a surrogate for exploratory chemistry. The new ligands were used to prepare well-defined [Re-oxo]3+ complexes where two pyridylthiosemicarbazide ligands were coordinated to a single metal ion to give bivalent complexes with two amyloid-β targeting functional groups. The interaction of the [Re-oxo]3+ complexes with synthetic amyloid-β1-42 and with amyloid plaques in human brain tissue was investigated. Two ligands were selected to develop methods to prepare their [99mTc-oxo]3+ complexes at the tracer level. These technetium-99?m complexes are likely to be isostructural to their rhenium-oxo analogues.
Synthesis of Oxorhenium(V) and Oxotechnetium(V) Complexes That Bind to Amyloid-β Plaques
Hayne, David J.,White, Jonathan M.,McLean, Catriona A.,Villemagne, Victor L.,Barnham, Kevin J.,Donnelly, Paul S.
, p. 7944 - 7953 (2016/08/24)
Alzheimer's disease is characterized by the presence of amyloid plaques in the brain. The primary constituents of the plaques are aggregated forms of the amyloid-β (Aβ) peptide. With the goal of preparing technetium-99m complexes that bind to Aβ plaques with the potential to be diagnostic imaging agents for Alzheimer's disease, new tetradentate ligands capable of forming neutral and lipophilic complexes with oxotechentium(V) and oxorhenium(V) were prepared. Nonradioactive isotopes of technetium are not available so rhenium was used as a surrogate for exploratory chemistry. Two planar tetradentate N3O ligands were prepared that form charge-neutral complexes with oxorhenium(v) as well as a ligand featuring a styrylpyridyl functional group designed to bind to Aβ plaques. All three ligands formed complexes with oxorhenium(V), and each complex was characterized by NMR spectroscopy, mass spectrometry, and X-ray crystallography. The oxorhenium(V) complex with a styrylpyridyl functional group binds to Aβ plaques present in post-mortem human brain tissue. The chemistry was extrapolated to technetium-99m at the tracer level for two of the ligands. The resulting oxotechnetium(V) complexes were sufficiently lipophilic and charge-neutral to suggest that they have the potential to cross the blood-brain barrier but exhibited modest stability with respect to exchange with histidine. The chemistry presented here identifies a strategy to integrate styrylpyridyl functional groups into tetradentate ligands capable of forming complexes with [M=O]3+ cores (M = Re or Tc).
