Indeno[1,2-b]indole derivatives as a novel class of potent human protein kinase CK2 inhibitors

Bioorg Med Chem. 2012 Apr 1;20(7):2282-9. doi: 10.1016/j.bmc.2012.02.017. Epub 2012 Feb 13.


Herein we describe the synthesis and properties of indeno[1,2-b]indole derivatives as a novel class of potent inhibitors of the human protein kinase CK2. A set of 19 compounds was obtained using a convenient and straightforward synthesis protocol. The compounds were tested for inhibition of human protein kinase CK2, which was recombinantly expressed in Escherichia coli. New inhibitors with IC(50) in the micro- and sub-micromolar range were identified. Compound 4b (5-isopropyl-7,8-dihydroindeno[1,2-b]indole-9,10(5H,6H)-dione) inhibited human CK2 with an IC(50) of 0.11 μM and did not significantly inhibit 22 other human protein kinases, suggesting selectivity towards CK2. ATP-competitive inhibition by compound 4b was shown and a K(i) of 0.06 μM was determined. Our findings indicate that indeno[1,2-b]indoles are a promising starting point for further development and optimization of human protein kinase CK2 inhibitors.

MeSH terms

  • Casein Kinase II / antagonists & inhibitors*
  • Casein Kinase II / metabolism
  • Cell Membrane Permeability / drug effects
  • Humans
  • Indoles / chemical synthesis
  • Indoles / chemistry*
  • Indoles / pharmacology
  • Kinetics
  • Protein Kinase Inhibitors / chemical synthesis
  • Protein Kinase Inhibitors / chemistry*
  • Protein Kinase Inhibitors / pharmacology
  • Stereoisomerism


  • Indoles
  • Protein Kinase Inhibitors
  • indole
  • Casein Kinase II