Discovery and evaluation of aza-fused tricyclic derivatives for detection of Tau pathology in Alzheimer?s disease

For various neurodegenerative diseases, including Alzheimer's disease (AD), the abnormal aggregation of Tau is not only the predominant contributing factor but also a major biomarker for disease diagnosis. In this study, a series of aza-fused tricyclic derivatives were designed and synthesized. By changing the position and number of nitrogen atoms on the fused tricyclic core, the imidazonaphthyridine scaffold was screened and reported for the first time which could potentially detect Tau aggregates. Through a series of in vitro and in vivo biological evaluations, probe [125I]5 possessed exceptional binding affinity (IC50 = 1.63 nM) to neurofibrillary tangles in the AD brain, high selectivity over A beta plaques (23.4-fold), clean off-target profile to monoamine oxidase A/B (MAO-A/B), and suitable pharmacokinetics (initial brain uptake = 3.22% ID/g).

Automated summary

In this study, a series of new aza-fused tricyclic derivatives were designed and synthesized. The imidazonaphthyridine scaffold was screened and reported for the first time, which has the potential to detect Tau aggregates. Probe [125I]5 showed exceptional binding affinity to neurofibrillary tangles in the AD brain, high selectivity over A beta plaques, clean off-target profile to MAO-A/B, and suitable pharmacokinetics.