Novel indanone derivatives as potential imaging probes for ß-amyloid plaques in the brain.

Molecular imaging probes to detect senile plaques (SPs) might help the early diagnosis of Alzheimer's disease (AD). In this study, a novel series of indanone derivatives were synthesized and characterized. In in vitro binding studies, compound 2e exhibited a K(i) value of 16 nM with a human AD brain homogenate. Although they displayed relatively low affinities for 2i and 2j--with K(i) values of 99 and 237 nM, respectively--the SPs in AD brain sections were positively stained by 2j. A method for in situ micro-autoradiography of AD brain was developed in this study and showed clear labeling of SPs by [(125)I]2i and [(125)I]2j. Both [(125)I]2i and [(125)I]2j had suitable lipophilicities and displayed high initial uptake and rapid clearance from the mouse brains. Furthermore, [(125)I]2i and [(125)I]2j were more stable in human brain homogenates than in mouse brain homogenates. These data suggest that such indanone derivatives might represent potential amyloid imaging agents for the detection of SPs in AD.

[Synthesis of benzothiazole derivatives and their binding characteristics with beta-amyloid].

Alzheimer's disease (AD) is a progressive neurodegenerative disease endangering human health seriously. Recent reports have revealed that beta-amyloid aggregates play a key role in the pathogenesis of AD. Thus, targeting the Abeta plaques benzothiazole derivatives were synthesized with the scaffold of the most promising imaging agent PIB ([11C]-6-OH-BTA-1, [11C]-2-(4-(methylamino)phenyl)-6-hydroxybenzothiazole) and C = N as linker to study the binding characteristics with the target protein through surface plasmon resonance (SPR) technique. These derivatives were synthesized through simple yet effective method with high yields and characterized by 1H NMR and FTIR. The binding properties (K(D)) were determined with Biacore X-100 instrument according to the fitting-plot curve. Compounds 3a and 3f showed high binding affinity for Abeta1-40. The results suggest that benzothiazole derivatives could be served as a scaffold to develop novel beta-amyloid imaging agents for the diagnosis of AD.

6-Methoxy-indanone derivatives as potential probes for ß-amyloid plaques in Alzheimer's disease.

A series of 6-methoxy indanone derivatives was synthesized and evaluated as potential probes for ß-amyloid plaque imaging in Alzheimer's disease (AD). Two derivatives (5d and 5k) displayed significant binding abilities in fluorescent staining experiments using the brain sections of AD patients. Two derivatives showed high binding affinities to ß-amyloid aggregates (5j, Ki = 5.82 ± 0.19 nM) and brain homogenates of AD patients (5j, Ki = 18.96 ± 0.28 nM) in in vitro binding assay. With a log P value of 3.45, [125I]5k exhibited an excellent initial brain uptake (5.29%ID g-1, 2 min after i.v.) and a fast clearance from the brain in biodistribution experiments in normal mice. In autoradiography, [125I]5k exhibited an obvious binding ability to ß-amyloid plaques and a relatively low nonspecific binding in the brain sections of AD patients (in vitro) and APP/PS1 transgenic mice (in vitro and ex vivo). Results suggest that 5k is a potential probe for detecting ß-amyloid plaques in vivo.