Discovery of CNS-Penetrant Apoptosis Signal-Regulating Kinase 1 (ASK1) Inhibitors.

Apoptosis signal-regulating kinase 1 (ASK1) is a key mediator in the apoptotic and inflammatory cellular stress response. To investigate the therapeutic value of modulating this pathway in neurological disease, we have completed medicinal chemistry studies to identify novel CNS-penetrant ASK1 inhibitors starting from peripherally restricted compounds reported in the literature. This effort led to the discovery of 21, a novel ASK1 inhibitor with good potency (cell IC50 = 138 nM), low clearance (rat Cl/Clu = 0.36/6.7 L h-1 kg-1) and good CNS penetration (rat K p,uu = 0.38).