Discovery and Evaluation of 7-Alkyl-1,5-bis-aryl-pyrazolopyridinones as Highly Potent, Selective, and Orally Efficacious Inhibitors of p38α Mitogen-Activated Protein Kinase^⊥⊥ Atomic coordinates and structure factors for crystal structure of compound3dwith p38α can be accessed using PDB code 3LHJ.

The p38 alpha mitogen-activated protein (MAP) kinase is a central signaling molecule in many proinflammatory pathways, regulating the cellular response to a multitude of external stimuli including heat, ultraviolet radiation, osmotic shock, and a variety of cytokines especially interleukin-1 beta and tumor necrosis factor alpha. Thus, inhibitors of this enzyme are postulated to have significant therapeutic potential for the treatment of rheumatoid arthritis, inflammatory bowel disease, and Crohn's disease, as well as other diseases where aberrant cytokine signaling is the driver of disease. In this communication, we describe a novel class of 7-alkyl-1,5-bis-aryl-pyrazolopyridinone-based p38 alpha inhibitors. In particular, compound 3f is highly potent in the enzyme and cell-based assays, selective in an Ambit kinase screen, and efficacious (ED50 <= 0.01 mg/kg) in the rat collagen induced arthritis (CIA) model.