The
synthesis and evaluation
of three novel 99mTc complexes (
99m
Tc-1–3) and their corresponding
Re complexes (Re-1–3), in which the
phenyl ring of 2-phenylbenzothiazole or 2-phenylbenzimidazole is replaced
by the cyclopentadienyl tricarbonyl [Cp99mTc(CO)3] core, are reported. Both 99mTc and Re complexes were
prepared from the corresponding ferrocenyl derivatives, and the Re
complexes were fully characterized by elemental analysis, spectroscopic
methods, and X-ray crystallography. The complexes exhibit effective
in vitro binding to β-amyloid (Aβ) plaques and fibrils,
inhibit Aβ fibril formation, and significantly reduce Aβ-induced
cytotoxicity and reactive oxygen species production in neuronal cell
cultures. The brain uptake of the 99mTc complexes ranges
between 7.94 and 3.99% ID/g at 2 min p.i., being the highest recorded
for potential 99mTc Aβ plaque imaging probes in mice.
Powered by their high brain uptake, the complexes represent strong
theranostic candidates against Alzheimer’s disease combining
single-photon-emission computed tomography diagnostic (99mTc complexes) and antiamyloid therapeutic (Re complexes) potential.