We report the discovery of 7-oxo-2,4,5,7-tetrahydro-6 H-pyrazolo[3,4- c]pyridine derivatives as a novel class of receptor interacting protein 1 (RIP1) kinase inhibitors. On the basis of the overlay study between HTS hit 10 and GSK2982772 (6) in RIP1 kinase, we designed and synthesized a novel class of RIP1 kinase inhibitor 11 possessing moderate RIP1 kinase inhibitory activity and P-gp mediated efflux. The optimization of the core structure and the exploration of appropriate substituents utilizing SBDD approach led to the discovery of 22, a highly potent, orally available, and brain-penetrating RIP1 kinase inhibitor with excellent PK profiles. Compound 22 significantly suppressed necroptotic cell death both in mouse and human cells. Oral administration of 22 (10 mg/kg, bid) attenuated disease progression in the mouse experimental autoimmune encephalomyelitis (EAE) model of multiple sclerosis (MS). Moreover, analysis of structure-kinetic relationship (SKR) for our novel chemical series was also discussed.

Apoptosis signal-regulating kinase 1 (ASK1/ MAP3K) is a mitogen-activated protein kinase family member shown to contribute to acute ischemia/reperfusion injury. Using structure-based drug design, deconstruction, and reoptimization of a known ASK1 inhibitor, a lead compound was identified. This compound displayed robust MAP3K pathway inhibition and reduction of infarct size in an isolated perfused heart model of cardiac injury. KEYWORDS:Apoptosis signal-regulating kinase 1 (ASK1), structure-based drug design (SBDD), cardiac injury A poptosis signal-regulating kinase 1 (ASK1) is a mitogenactivated protein kinase kinase kinase (MAP3K) family member residing upstream of both Jun N-terminal kinase (JNK) and p38. ASK1 is capable of activating JNK and P38 via the phosphorylation of intermediate kinases. ASK1 plays a role in the mammalian cell stress response and the induction of apoptotic cell death. It also contributes to a range of systemic diseases including heart failure 1 and acute ischemia/reperfusion injury, by reducing structural and functional integrity of the mitochondria in cardiac cells. 2−4 ASK1-deficient mice display reduced levels of cardiomyocyte apoptosis, hypertrophy, and interstitial fibrosis. 5 Thus, selective inhibition of ASK1 represents an attractive strategy for slowing or potentially reversing harmful tissue changes associated with various forms of heart failure.Using ASK1 structural information and deconstruction of known ASK1 inhibitors such as 1 and 2 (Figure 1), our research team generated a novel, potent, and orally bioavailable ASK1 inhibitor with favorable physicochemical properties to help further elucidate the role of ASK1 in cardiac injury. Compound 1 was an early lead for Takeda's ASK1 inhibitor program. 6 Compound 2 (GS-4997, Gilead Sciences) is a clinical stage ASK1 inhibitor, which has been evaluated as an experimental treatment for diabetic nephropathy and kidney fibrosis. 7 Key structural features with respect to ligand interactions within the ATP binding site were identified using our internal database as well as public domain crystal structures of small molecules in ASK1 and published pharmacophore models. 8,9 Figure 1 illustrates the cocrystal structure of 1 in hASK1 (PDB: 3VW6) and highlights the key interactions between 1 and the ASK1 ATP binding pocket. Binding to the kinase hinge is characterized by a hydrogen bonding interaction with the

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[This corrects the article DOI: 10.1021/acsmedchemlett.6b00481.].