Identification of Novel Chemical Scaffolds Inhibiting Trypanothione Synthetase from Pathogenic Trypanosomatids.

Diego Benítez (1) , Andrea Medeiros (1, 2) , Lucía Fiestas (1) , Esteban A Panozzo-Zenere (3) , Franziska Maiwald (4) , Kyriakos C Prousis (5) , Marina Roussaki (6) , Theodora Calogeropoulou (5) , Anastasia Detsi (6) , Timo Jaeger (7) , Jonas Šarlauskas (8) , Lucíja Peterlin Mašič (9) , Conrad Kunick (4) , Guillermo R Labadie (10, 3) , Leopold Flohé (11) , Marcelo A Comini (1)

1 Institut Pasteur de Montevideo
2 UDELAR - Universidad de la República [Montevideo]
3 Universidad Nacional de Rosario [Santa Fe]
4 Technische Universität Braunschweig = Technical University of Braunschweig [Braunschweig]
5 National Hellenic Research Foundation [Athens]
6 NTUA - National Technical University of Athens [Athens]
7 German Centre for Infection Research
8 Vilnius University [Vilnius]
9 University of Ljubljana
10 IQUIR - Instituto de Química Rosario
11 Unipd - Università degli Studi di Padova = University of Padua

BACKGROUND: The search for novel chemical entities targeting essential and parasite-specific pathways is considered a priority for neglected diseases such as trypanosomiasis and leishmaniasis. The thiol-dependent redox metabolism of trypanosomatids relies on bis-glutathionylspermidine [trypanothione, T(SH)2], a low molecular mass cosubstrate absent in the host. In pathogenic trypanosomatids, a single enzyme, trypanothione synthetase (TryS), catalyzes trypanothione biosynthesis, which is indispensable for parasite survival. Thus, TryS qualifies as an attractive drug target candidate.

METHODOLOGY/PRINCIPAL FINDING: A library composed of 144 compounds from 7 different families and several singletons was screened against TryS from three major pathogen species (Trypanosoma brucei, Trypanosoma cruzi and Leishmania infantum). The screening conditions were adjusted to the TryS´ kinetic parameters and intracellular concentration of substrates corresponding to each trypanosomatid species, and/or to avoid assay interference. The screening assay yielded suitable Z' and signal to noise values (≥0.85 and ~3.5, respectively), and high intra-assay reproducibility. Several novel chemical scaffolds were identified as low μM and selective tri-tryp TryS inhibitors. Compounds displaying multi-TryS inhibition (N,N'-bis(3,4-substituted-benzyl) diamine derivatives) and an N5-substituted paullone (MOL2008) halted the proliferation of infective Trypanosoma brucei (EC50 in the nM range) and Leishmania infantum promastigotes (EC50 = 12 μM), respectively. A bis-benzyl diamine derivative and MOL2008 depleted intracellular trypanothione in treated parasites, which confirmed the on-target activity of these compounds.

CONCLUSIONS/SIGNIFICANCE: Novel molecular scaffolds with on-target mode of action were identified as hit candidates for TryS inhibition. Due to the remarkable species-specificity exhibited by tri-tryp TryS towards the compounds, future optimization and screening campaigns should aim at designing and detecting, respectively, more potent and broad-range TryS inhibitors.

Domaines: Sciences du Vivant [q-bio]

Diego Benítez, Andrea Medeiros, Lucía Fiestas, Esteban A Panozzo-Zenere, Franziska Maiwald, et al.. Identification of Novel Chemical Scaffolds Inhibiting Trypanothione Synthetase from Pathogenic Trypanosomatids.. PLoS Neglected Tropical Diseases, 2016, 10 (4), pp.e0004617. ⟨10.1371/journal.pntd.0004617⟩. ⟨pasteur-01498320⟩