Trypanosoma cruzi: effect and mode of action of nitroimidazole and nitrofuran derivatives

SUMMARYThe phenotypic activity of two 5-nitroindazolinones, i.e. 2-benzyl-1-propyl (22) and 2-benzyl-1-butyl (24) derivatives, previously proposed as anti-Trypanosoma cruzi prototypes, was presently assayed on bloodstream trypomastigotes (BT) of the moderately drug-resistant Y strain. Further exploration of putative targets and cellular mechanisms involved in their activity was also carried out. Therefore, transmission electron microscopy, high-resolution respirometry and flow cytometry procedures were performed on BT treated for up to 24 h with the respective EC50 value of each derivative. Results demonstrated that although 22 and 24 were not as active as benznidazole in this in vitro assay on BT, both compounds triggered important damages in T. cruzi that lead to the parasite death. Ultrastructural alterations included shedding events, detachment of plasma membrane and nuclear envelope, loss of mitochondrial integrity, besides the occurrence of a large number of intracellular vesicles and profiles of endoplasmic reticulum surrounding cytoplasmic organelles such as mitochondrion. Moreover, both derivatives affected mitochondrion leading to this organelle dysfunction, as reflected by the inhibition in oxygen consumption and the loss of mitochondrial membrane potential. Altogether, the findings exposed in the present study propose autophagic processes and mitochondrial machinery as part of the mode of action of both 5-nitroindazolinones 22 and 24 on T. cruzi trypomastigotes.

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Identification of a proteasome-targeting arylsulfonamide with potential for the treatment of Chagas’ disease

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01535-21 ◽

2021 ◽

Author(s):

Marta Lima ◽

Lindsay B Tulloch ◽

Victoriano Corpas-Lopez ◽

Sandra Carvalho ◽

Richard J. Wall ◽

...

Keyword(s):

Drug Discovery ◽

Trypanosoma Cruzi ◽

Chagas Disease ◽

Causative Agent ◽

Mode Of Action ◽

Malic Enzyme ◽

Proteasome Inhibitors ◽

Genetically Engineered ◽

Phenotypic Screening

Phenotypic screening identified an arylsulfonamide compound with activity against Trypanosoma cruzi , the causative agent of Chagas’ disease. Comprehensive mode of action studies revealed that this compound primarily targets the T. cruzi proteasome, binding at the interface between β4 and β5 subunits that catalyse chymotrypsin-like activity. A mutation in the β5 subunit of the proteasome was associated with resistance to compound 1 , while overexpression of this mutated subunit also reduced susceptibility to compound 1 . Further genetically engineered and in vitro selected clones resistant to proteasome inhibitors known to bind at the β4/β5 interface were cross-resistant to compound 1 . Ubiquitinylated proteins were additionally found to accumulate in compound 1 -treated epimastigotes. Finally, thermal proteome profiling identified malic enzyme as a secondary target of compound 1 , although malic enzyme inhibition was not found to drive potency. These studies identify a novel pharmacophore capable of inhibiting the T. cruzi proteasome that may be exploitable for anti-chagasic drug discovery.

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