Carbonic anhydrase inhibitors. Inhibition of the transmembrane isozyme XII with sulfonamides-a new target for the design of antitumor and antiglaucoma drugs?

Bioorg Med Chem Lett. 2005 Feb 15;15(4):963-9. doi: 10.1016/j.bmcl.2004.12.053.


The inhibition of a newly cloned human carbonic anhydrase (CA, EC, isozyme XII (hCA XII), has been investigated with a series of sulfonamides, including some clinically used derivatives (acetazolamide, methazolamide, ethoxzolamide, dichlorophenamide, dorzolamide, brinzolamide, benzolamide, and sulpiride, or indisulam, a compound in clinical development as antitumor drug), as well as the sulfamate antiepileptic drug topiramate. Some simple amino-/hydrazine-/hydroxy-substituted aromatic/heterocyclic sulfonamides have also been included in the study. All types of activity have been detected, with several medium potency inhibitors (K(I)s in the range of 34-220 nM), whereas ethoxzolamide and several halogenated sulfanilamides showed stronger potency, with K(I)s in the range of 11-22 nM. The antiglaucoma sulfonamides used clinically, except dichlorophenamide, which is a moderate inhibitor (K(I) of 50 nM), as well as topiramate, indisulam, and sulpiride behave as very potent hCA XII inhibitors, with K(I)s in the range of 3.0-5.7 nM. Several subnanomolar inhibitors (K(I)s in the range of 0.30-0.85 nM) have also been detected. Compounds with excellent selectivity against hCA XII over hCA II have been found, showing selectivity ratios in the range of 177.7-566.7. Apparently, hCA XII is a target of the antiglaucoma sulfonamides, and potent hCA XII inhibitors may be developed/used for the management of hypoxic tumors, together with inhibitors of the other tumor-associated isozyme, CA IX.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents
  • Carbonic Anhydrase Inhibitors / chemistry
  • Carbonic Anhydrase Inhibitors / pharmacology*
  • Carbonic Anhydrases / chemistry
  • Carbonic Anhydrases / drug effects*
  • Drug Design
  • Glaucoma / drug therapy
  • Humans
  • Isoenzymes
  • Structure-Activity Relationship
  • Sulfonamides / chemistry
  • Sulfonamides / pharmacology*


  • Antineoplastic Agents
  • Carbonic Anhydrase Inhibitors
  • Isoenzymes
  • Sulfonamides
  • Carbonic Anhydrases
  • carbonic anhydrase XII