Inhibitory effects and structural insights for a novel series of coumarin-based compounds that selectively target human CA IX and CA XII carbonic anhydrases

Eur J Med Chem. 2018 Jan 1:143:276-282. doi: 10.1016/j.ejmech.2017.11.061. Epub 2017 Nov 23.

Abstract

Coumarin derivatives are a peculiar class of inhibitors of the family of metalloenzymes carbonic anhydrases (CA, EC 4.2.1.1). Several coumarins display higher affinity and selectivity toward most relevant and druggable CA isoforms. By decorating the natural compound umbelliferone (1) we have identified a new series of coumarin-based compounds demonstrating high CA inhibitory effects with nanomolar affinity for hCA IX and hCA XII isoforms that were considered a target amenable to develop antitumor agents. The most active tested compounds proved to be potent inhibitors with Ki values equal to that of the well-known inhibitor acetazolamide (AAZ), that lacks selectivity over ubiquitous hCA I and hCA II. As suggested by docking studies the coumarins, that are lacking of the canonical metal binding groups, do not interact with Zinc ion within the catalytic site as found for classical sulfonamide type inhibitors of CAs. Thus, the studied inhibitors might possess a non-classical inhibitory mode of action preventing the carbon dioxide to entry into catalytic cavity and its conversion into bicarbonate ion. Specifically, the most active inhibitor of hCA XII compound 18i (Ki value of 5.5 nM) and its supposed hydrolytic products could establish a web of H-bond interactions within the enzymatic cavity.

Keywords: Antitumor agents; Coumarins; Molecular docking; hCA IX; hCA XII; hCAs.

MeSH terms

  • Antigens, Neoplasm / metabolism
  • Carbonic Anhydrase IX / antagonists & inhibitors*
  • Carbonic Anhydrase IX / metabolism
  • Carbonic Anhydrase Inhibitors / chemical synthesis
  • Carbonic Anhydrase Inhibitors / chemistry
  • Carbonic Anhydrase Inhibitors / pharmacology*
  • Carbonic Anhydrases / metabolism*
  • Coumarins / chemical synthesis
  • Coumarins / chemistry
  • Coumarins / pharmacology*
  • Dose-Response Relationship, Drug
  • Humans
  • Molecular Docking Simulation
  • Molecular Structure
  • Structure-Activity Relationship

Substances

  • Antigens, Neoplasm
  • Carbonic Anhydrase Inhibitors
  • Coumarins
  • CA9 protein, human
  • Carbonic Anhydrase IX
  • Carbonic Anhydrases
  • carbonic anhydrase XII