Identification of Trypanosoma brucei AdoMetDC Inhibitors Using a High-Throughput Mass Spectrometry-Based Assay

ACS Infect Dis. 2017 Jul 14;3(7):512-526. doi: 10.1021/acsinfecdis.7b00022. Epub 2017 Apr 7.


Human African trypanosomiasis (HAT) is a fatal infectious disease caused by the eukaryotic pathogen Trypanosoma brucei (Tb). Available treatments are difficult to administer and have significant safety issues. S-Adenosylmethionine decarboxylase (AdoMetDC) is an essential enzyme in the parasite polyamine biosynthetic pathway. Previous attempts to develop TbAdoMetDC inhibitors into anti-HAT therapies failed due to poor brain exposure. Here, we describe a large screening campaign of two small-molecule libraries (∼400,000 compounds) employing a new high-throughput (∼7 s per sample) mass spectrometry-based assay for AdoMetDC activity. As a result of primary screening, followed by hit confirmation and validation, we identified 13 new classes of reversible TbAdoMetDC inhibitors with low-micromolar potency (IC50) against both TbAdoMetDC and T. brucei parasite cells. The majority of these compounds were >10-fold selective against the human enzyme. Importantly, compounds from four classes demonstrated high propensity to cross the blood-brain barrier in a cell monolayer assay. Biochemical analysis demonstrated that compounds from eight classes inhibited intracellular TbAdoMetDC in the parasite, although evidence for a secondary off-target component was also present. The discovery of several new TbAdoMetDC inhibitor chemotypes provides new hits for lead optimization programs aimed to deliver a novel treatment for HAT.

Keywords: AdoMetDC; Trypanosoma brucei; high-throughput screening; human African trypanosomiasis; mass spectrometry.

Publication types

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

MeSH terms

  • Adenosylmethionine Decarboxylase / antagonists & inhibitors*
  • Adenosylmethionine Decarboxylase / genetics
  • Adenosylmethionine Decarboxylase / metabolism
  • Animals
  • Blood-Brain Barrier / drug effects
  • Blood-Brain Barrier / metabolism
  • Dogs
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / pharmacology*
  • Gene Expression
  • High-Throughput Screening Assays*
  • Humans
  • Kinetics
  • Madin Darby Canine Kidney Cells
  • Mass Spectrometry / instrumentation
  • Mass Spectrometry / methods
  • Models, Biological
  • Parasitic Sensitivity Tests
  • Permeability
  • Protozoan Proteins / antagonists & inhibitors*
  • Protozoan Proteins / genetics
  • Protozoan Proteins / metabolism
  • Small Molecule Libraries / chemistry
  • Small Molecule Libraries / pharmacology*
  • Structure-Activity Relationship
  • Trypanocidal Agents / chemistry
  • Trypanocidal Agents / pharmacology*
  • Trypanosoma brucei brucei / drug effects*
  • Trypanosoma brucei brucei / enzymology
  • Trypanosoma brucei brucei / genetics
  • Trypanosoma brucei brucei / growth & development


  • Enzyme Inhibitors
  • Protozoan Proteins
  • Small Molecule Libraries
  • Trypanocidal Agents
  • Adenosylmethionine Decarboxylase