Synthesis and structure-activity relationships of N-6 substituted analogues of 9-hydroxy-4-phenylpyrrolo[3,4-c]carbazole-1,3(2H,6H)-diones as inhibitors of Wee1 and Chk1 checkpoint kinases

Eur J Med Chem. 2008 Jun;43(6):1276-96. doi: 10.1016/j.ejmech.2007.07.016. Epub 2007 Aug 6.


A series of N-6 substituted 9-hydroxy-4-phenylpyrrolo[3,4-c]carbazole-1,3(2H,6H)-diones were prepared from N-substituted (5-methoxyphenyl)ethenylindoles. The target compounds were tested for their ability to inhibit the G2/M cell cycle checkpoint kinases, Wee1 and Chk1. Analogues with neutral or cationic N-6 side chains were potent dual inhibitors. Acidic side chains provided potent (average IC(50) 0.057 microM) and selective (average ratio 223-fold) Wee1 inhibition. Co-crystal structures of inhibitors bound to Wee1 show that the pyrrolo[3,4-c]carbazole scaffold binds in the ATP-binding site, with N-6 substituents involved in H-bonding to conserved water molecules. HT-29 cells treated with doxorubicin and then target compounds demonstrate an active Cdc2/cyclin B complex, inhibition of the doxorubicin-induced phosphorylation of tyrosine 15 of Cdc2 and abrogation of the G2 checkpoint.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carbazoles / chemical synthesis*
  • Carbazoles / chemistry
  • Carbazoles / pharmacology*
  • Cell Cycle Proteins / antagonists & inhibitors*
  • HT29 Cells
  • Humans
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Nuclear Proteins / antagonists & inhibitors*
  • Protein Kinase Inhibitors / chemical synthesis*
  • Protein Kinase Inhibitors / chemistry
  • Protein Kinase Inhibitors / pharmacology*
  • Protein-Tyrosine Kinases / antagonists & inhibitors*
  • Structure-Activity Relationship


  • Carbazoles
  • Cell Cycle Proteins
  • Nuclear Proteins
  • Protein Kinase Inhibitors
  • Protein-Tyrosine Kinases
  • WEE1 protein, human