Pharmacological Validation of Trypanosoma Brucei Phosphodiesterases B1 and B2 as Druggable Targets for African Sleeping Sickness

J Med Chem. 2011 Dec 8;54(23):8188-94. doi: 10.1021/jm201148s. Epub 2011 Nov 8.


Neglected tropical disease drug discovery requires application of pragmatic and efficient methods for development of new therapeutic agents. In this report, we describe our target repurposing efforts for the essential phosphodiesterase (PDE) enzymes TbrPDEB1 and TbrPDEB2 of Trypanosoma brucei , the causative agent for human African trypanosomiasis (HAT). We describe protein expression and purification, assay development, and benchmark screening of a collection of 20 established human PDE inhibitors. We disclose that the human PDE4 inhibitor piclamilast, and some of its analogues, show modest inhibition of TbrPDEB1 and B2 and quickly kill the bloodstream form of the subspecies T. brucei brucei . We also report the development of a homology model of TbrPDEB1 that is useful for understanding the compound-enzyme interactions and for comparing the parasitic and human enzymes. Our profiling and early medicinal chemistry results strongly suggest that human PDE4 chemotypes represent a better starting point for optimization of TbrPDEB inhibitors than those that target any other human PDEs.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • 3',5'-Cyclic-AMP Phosphodiesterases / antagonists & inhibitors
  • 3',5'-Cyclic-AMP Phosphodiesterases / metabolism*
  • Benzamides / chemical synthesis
  • Benzamides / chemistry
  • Benzamides / pharmacology
  • Catalytic Domain
  • Humans
  • Models, Molecular
  • Molecular Structure
  • Pyridines / chemical synthesis
  • Pyridines / chemistry
  • Pyridines / pharmacology
  • Recombinant Proteins / antagonists & inhibitors
  • Recombinant Proteins / chemistry
  • Structure-Activity Relationship
  • Trypanocidal Agents / chemical synthesis
  • Trypanocidal Agents / chemistry*
  • Trypanocidal Agents / pharmacology
  • Trypanosoma brucei brucei / drug effects
  • Trypanosoma brucei brucei / enzymology*
  • Trypanosomiasis, African / drug therapy*


  • Benzamides
  • Pyridines
  • Recombinant Proteins
  • Trypanocidal Agents
  • 3',5'-Cyclic-AMP Phosphodiesterases
  • piclamilast