Reversible cysteine protease inhibitors show promise for a Chagas disease cure

Antimicrob Agents Chemother. 2014;58(2):1167-78. doi: 10.1128/AAC.01855-13. Epub 2013 Dec 9.


The cysteine protease cruzipain is essential for the viability, infectivity, and virulence of Trypanosoma cruzi, the causative agent of Chagas disease. Thus, inhibitors of cruzipain are considered promising anti-T. cruzi chemotherapeutic agents. Reversible cruzipain inhibitors containing a nitrile "warhead" were prepared and demonstrated 50% inhibitory concentrations (IC50s) as potent as 1 nM in baculovirus-generated cruzipain enzyme assays. In epimastigote and intracellular amastigote in vitro assays, the most potent compounds demonstrated antiparasitic behavior in the 5 to 10 μM IC50 range; however, trypomastigote production from the amastigote form was ∼90 to 95% inhibited at 2 μM. Two key compounds, Cz007 and Cz008, with IC50s of 1.1 and 1.8 nM, respectively, against the recombinant enzyme were tested in a murine model of acute T. cruzi infection, with oral dosing in chow for 28 days at doses from 3 to 50 mg/kg of body weight. At 3 mg/kg of Cz007 and 3 mg/kg of Cz008, the blood parasitemia areas under the concentration-time curves were 16% and 25% of the untreated group, respectively. At sacrifice, 24 days after immunosuppression with cyclophosphamide, parasite presence in blood, heart, and esophagus was evaluated. Based on negative quantitative PCR results in all three tissues, cure rates in surviving animals were 90% for Cz007 at 3 mg/kg, 78% for Cz008 at 3 mg/kg, and 71% for benznidazole, the control compound, at 50 mg/kg.

MeSH terms

  • Administration, Oral
  • Animals
  • Area Under Curve
  • Chagas Disease / drug therapy*
  • Chagas Disease / mortality
  • Chagas Disease / parasitology
  • Cysteine Endopeptidases / metabolism*
  • Cysteine Proteinase Inhibitors / chemical synthesis
  • Cysteine Proteinase Inhibitors / pharmacology*
  • Inhibitory Concentration 50
  • Life Cycle Stages / drug effects
  • Life Cycle Stages / physiology
  • Male
  • Mice
  • Nitroimidazoles / pharmacology
  • Parasitemia / drug therapy*
  • Parasitemia / mortality
  • Protozoan Proteins / antagonists & inhibitors*
  • Protozoan Proteins / metabolism
  • Survival Analysis
  • Treatment Outcome
  • Trypanocidal Agents / chemical synthesis
  • Trypanocidal Agents / pharmacology*
  • Trypanosoma cruzi / drug effects
  • Trypanosoma cruzi / physiology


  • Cysteine Proteinase Inhibitors
  • Nitroimidazoles
  • Protozoan Proteins
  • Trypanocidal Agents
  • Cysteine Endopeptidases
  • cruzipain
  • benzonidazole