Structure-activity relationships of the p38alpha MAP kinase inhibitor 1-(5-tert-butyl-2-p-tolyl-2H-pyrazol-3-yl)-3-[4-(2-morpholin-4-yl-ethoxy)naph- thalen-1-yl]urea (BIRB 796)

J Med Chem. 2003 Oct 23;46(22):4676-86. doi: 10.1021/jm030121k.


We report on the structure-activity relationships (SAR) of 1-(5-tert-butyl-2-p-tolyl-2H-pyrazol-3-yl)-3-[4-(2-morpholin-4-yl-ethoxy)naphthalen-1-yl]urea (BIRB 796), an inhibitor of p38alpha MAP kinase which has advanced into human clinical trials for the treatment of autoimmune diseases. Thermal denaturation was used to establish molecular binding affinities for this class of p38alpha inhibitors. The tert-butyl group remains a critical binding element by occupying a lipophilic domain in the kinase which is exposed upon rearrangement of the activation loop. An aromatic ring attached to N-2 of the pyrazole nucleus provides important pi-CH(2) interactions with the kinase. The role of groups attached through an ethoxy group to the 4-position of the naphthalene and directed into the ATP-binding domain is elucidated. Pharmacophores with good hydrogen bonding potential, such as morpholine, pyridine, and imidazole, shift the melting temperature of p38alpha by 16-17 degrees C translating into K(d) values of 50-100 pM. Finally, we describe several compounds that potently inhibit TNF-alpha production when dosed orally in mice.

MeSH terms

  • Animals
  • Cell Line
  • Crystallography, X-Ray
  • Enzyme Inhibitors / chemical synthesis*
  • Enzyme Inhibitors / chemistry
  • Enzyme-Linked Immunosorbent Assay
  • Heating
  • Humans
  • In Vitro Techniques
  • Ligands
  • Lipopolysaccharides / pharmacology
  • Mice
  • Mitogen-Activated Protein Kinase 14
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors*
  • Mitogen-Activated Protein Kinases / chemistry
  • Naphthalenes / chemical synthesis*
  • Naphthalenes / chemistry
  • Protein Binding
  • Protein Denaturation
  • Pyrazoles / chemical synthesis*
  • Pyrazoles / chemistry
  • Structure-Activity Relationship
  • Tumor Necrosis Factor-alpha / antagonists & inhibitors
  • Tumor Necrosis Factor-alpha / biosynthesis
  • Urea / analogs & derivatives*
  • Urea / chemical synthesis*
  • Urea / chemistry


  • Enzyme Inhibitors
  • Ligands
  • Lipopolysaccharides
  • Naphthalenes
  • Pyrazoles
  • Tumor Necrosis Factor-alpha
  • Urea
  • Mitogen-Activated Protein Kinase 14
  • Mitogen-Activated Protein Kinases
  • doramapimod