^99mTc-labeled dibenzylideneacetone derivatives as potential SPECT probes for in vivo imaging of β-amyloid plaque

Four ^99mTc-labeled dibenzylideneacetone derivatives and corresponding rhenium complexes were successfully synthesized and biologically evaluated as potential imaging probes for Aβ plaques using SPECT. All rhenium complexes (5a-d) showed affinity for Aβ_(1-42) aggregates (K_i = 13.6-120.9 nM), and selectively stained the Aβ plaques on brain sections of transgenic mice. Biodistribution in normal mice revealed that [^99mTc]5a-d exhibited moderate initial uptake (0.31%-0.49% ID/g at 2 min) and reasonable brain washout at 60 min post-injection. Although additional optimizations are still needed to facilitate it's penetration through BBB, the present results indicate that [^99mTc]5a may be a potential SPECT probe for imaging Aβ plaques in Alzheimer's brains.