Discovery of novel imidazole chemotypes as isoform-selective JNK3 inhibitors for the treatment of Alzheimer's disease

Despite innumerable efforts to develop effective therapeutics, it is difficult to achieve breakthrough treatments for Alzheimer's disease (AD), and the main reason is probably the absence of a clear target. Here, we reveal c-Jun N-terminal kinase 3 (JNK3), a protein kinase explicitly expressed in the brain and involved in neuronal apoptosis, with a view toward providing effective treatment for AD. For many years, we have worked on JNK3 inhibitors and have discovered 2-aryl-1-pyrimidinyl-1H-imidazole-5-yl acetonitrile-based JNK3 inhibitors with superb potency (IC50 < 1.0 nM) and excellent selectivity over other protein kinases including isoforms JNK1 (>300 fold) and JNK2 (∼10 fold). Based on in vitro biological activity and DMPK properties, the lead compounds were selected for further in vivo studies. We confirmed that repeat administration of JNK3 inhibitors improved cognitive memory in APP/PS1 and the 3xTg mouse model. Overall, our results show that JNK3 could be a potential target protein for AD.