title: Trypanosoma cruzi CYP51 inhibitor derived from a Mycobacterium tuberculosis screen hit.
abstract: BACKGROUND
  The two front-line drugs for chronic Trypanosoma cruzi infections are limited by adverse side-effects and declining efficacy. One potential new target for Chagas' disease chemotherapy is sterol 14alpha-demethylase (CYP51), a cytochrome P450 enzyme involved in biosynthesis of membrane sterols.
  
  
  RESULTS
  In a screening effort targeting Mycobacterium tuberculosis CYP51 (CYP51(Mt)), we previously identified the N-[4-pyridyl]-formamide moiety as a building block capable of delivering a variety of chemotypes into the CYP51 active site. In that work, the binding modes of several second generation compounds carrying this scaffold were determined by high-resolution co-crystal structures with CYP51(Mt). Subsequent assays against the CYP51 orthologue in T. cruzi, CYP51(Tc), demonstrated that two of the compounds tested in the earlier effort bound tightly to this enzyme. Both were tested in vitro for inhibitory effects against T. cruzi and the related protozoan parasite Trypanosoma brucei, the causative agent of African sleeping sickness. One of the compounds had potent, selective anti-T. cruzi activity in infected mouse macrophages. Cure of treated host cells was confirmed by prolonged incubation in the absence of the inhibiting compound. Discrimination between T. cruzi and T. brucei CYP51 by the inhibitor was largely based on the variability (phenylalanine versus isoleucine) of a single residue at a critical position in the active site.
  
  
  CONCLUSIONS
  CYP51(Mt)-based crystal structure analysis revealed that the functional groups of the two tightly bound compounds are likely to occupy different spaces in the CYP51 active site, suggesting the possibility of combining the beneficial features of both inhibitors in a third generation of compounds to achieve more potent and selective inhibition of CYP51(Tc).
authors.affiliation: Department of Pharmaceutical Chemistry, University of California, San Francisco, California, United States of America.
authors.forename: Chiung-Kuang
authors.initials: CK
authors.lastname: Chen
authors.forename: Patricia S
authors.initials: PS
authors.lastname: Doyle
authors.forename: Liudmila V
authors.initials: LV
authors.lastname: Yermalitskaya
authors.forename: Zachary B
authors.initials: ZB
authors.lastname: Mackey
authors.forename: Kenny K H
authors.initials: KK
authors.lastname: Ang
authors.forename: James H
authors.initials: JH
authors.lastname: McKerrow
authors.forename: Larissa M
authors.initials: LM
authors.lastname: Podust
mesh_terms: D000818:Animals; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D014355:Chagas Disease / Q000188:drug therapy / Q000469:parasitology; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System; D004791:Enzyme Inhibitors / Q000009:adverse effects / Q000494:pharmacology* / Q000627:therapeutic use*; D006801:Humans; D020128:Inhibitory Concentration 50; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000201:enzymology*; D021261:Parasitic Sensitivity Tests; D014344:Trypanocidal Agents / Q000009:adverse effects / Q000494:pharmacology* / Q000627:therapeutic use*; D014349:Trypanosoma cruzi / Q000187:drug effects / Q000201:enzymology
chemical_list: C509352:CYP51 protein, Trypanosoma cruzi; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D014344:Trypanocidal Agents; D003577:Cytochrome P-450 Enzyme System