Structure−Activity Relationship of Imidazo[1,2-<i>a</i>]pyridines as Ligands for Detecting β-Amyloid Plaques in the Brain
作者:Zhi-Ping Zhuang、Mei-Ping Kung、Alan Wilson、Chi-Wan Lee、Karl Plössl、Catherine Hou、David M. Holtzman、Hank F. Kung
DOI:10.1021/jm020351j
日期:2003.1.1
A series of novel beta-amyloid (Abeta) aggregate-specific ligands, 2-(4'-dimethylaminophenyl)-6-iodoimidazo[1,2-alpha]pyridine, (IMPY), and its related derivatives were prepared. An in vitro binding study with preformed Abeta aggregates showed that 16(IMPY) and its bromo derivative competed with binding of 2-(4'-dimethylaminophenyl)-6-iodobenzothiazole, [I-125]7(TZDM), a known ligand for Abeta aggregates, with high binding affinities (K-i = 15 and 10 nM, respectively). In vitro autoradiography of brain sections of a transgenic mouse (Tg2576) with [I-125]16(IMPY) displayed high selective binding to amyloid-like structures, comparable to that observed by staining with thioflavin-S visualized under fluorescence. In vivo biodistribution after an intravenous injection of [I-125]16(IMPY) in normal mice showed a high initial brain uptake and fast washout, indicating a low background activity associated with this iodinated ligand. Taken together, the data suggests that [I-123]16(IMPY) may be useful for imaging Abeta aggregates in patients with Alzheimer's disease.