Efficacy of Novel Pyrazolone Phosphodiesterase Inhibitors in Experimental Mouse Models of Trypanosoma cruzi

Julianna Siciliano de Araújo, Cristiane França da Silva, Denise da Gama Jaén Batista, Aline Nefertiti, Ludmila Ferreira de Almeida Fiuza, Cristina Rosa Fonseca-Berzal, Patrícia Bernardino da Silva, Marcos Meuser Batista, Maarten Sijm, Titilola D. Kalejaiye, Harry P. de Koning, Louis Maes, Geert Jan Sterk, Rob Leurs, Maria de Nazaré Correia Soeiro

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Pyrazolones are heterocyclic compounds with interesting biological properties. Some derivatives inhibit phosphodiesterases (PDEs) and thereby increase the cellular concentration of cyclic AMP (cAMP), which plays a vital role in the control of metabolism in eukaryotic cells, including the protozoan Trypanosoma cruzi, the etiological agent of Chagas disease (CD), a major neglected tropical disease. In vitro phenotypic screening identified a 4-bromophenyl-dihydropyrazole dimer as an anti-T. cruzi hit and 17 novel pyrazolone analogues with variations on the phenyl ring were investigated in a panel of phenotypic laboratory models. Potent activity against the intracellular forms (Tulahuen and Y strains) was obtained with 50% effective concentration (EC50) values within the 0.17 to 3.3 μM range. Although most were not active against bloodstream trypomastigotes, an altered morphology and loss of infectivity were observed. Pretreatment of the mammalian host cells with pyrazolones did not interfere with infection and proliferation, showing that the drug activity was not the result of changes to host cell metabolism. The pyrazolone NPD-227 increased the intracellular cAMP levels and was able to sterilize T. cruzi-infected cell cultures. Thus, due to its high potency and selectivity in vitro, and its additive interaction with benznidazole (Bz), NPD-227 was next assessed in the acute mouse model. Oral dosing for 5 days of NPD-227 at 10 mg/kg + Bz at 10 mg/kg not only reduced parasitemia (>87%) but also protected against mortality (>83% survival), hence demonstrating superiority to the monotherapy schemes. These data support these pyrazolone molecules as potential novel therapeutic alternatives for Chagas disease.

Original languageEnglish
Article numbere00414-20
Pages (from-to)1-11
Number of pages11
JournalAntimicrobial agents and chemotherapy
Issue number9
Publication statusPublished - 20 Aug 2020


  • Chagas disease
  • experimental chemotherapy
  • phosphodiesterase inhibitors
  • pyrazolone derivatives
  • Trypanosoma cruzi


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