Benzothiazole Schiff-bases as potential imaging agents for β-amyloid plaques in Alzheimer's disease

A series of benzothiazole Schiff-bases as potential diagnostic imaging agents targeting beta-amyloid (A beta) plaques in Alzheimer's disease (AD) were synthesized and evaluated. When in vitro binding studies using AD homogenate with [I-125] 6-iodo-2-(4'-dimethyl- amino)-phenyl-imidazo[1,2-alpha]pyridine ([I-125]IMPY) as the reference ligand were carried out with the derivatives, the compounds showed high to low binding affinities for AD homogenate at the K (i) values ranged from 4.38 to 514.65 nM, depending on the substitution on the phenyl ring. Fluorescent staining in vitro showed that one compound with a N,N-dimethylamino group intensely stained A beta plaques within brain sections of postmortem AD patients. The results strongly suggest that these derivatives are worthy of further study and may be a useful amyloid imaging agents for early detection of amyloid plaques in the brain of AD.