Initial studies on mechanism of action and cell death of active N-oxide-containing heterocycles in Trypanosoma cruzi epimastigotes in vitro.
Chagas disease, endemic in 21 countries across Latin America, kills more people in the region each year than any other parasite-borne disease. Therapeutic options have problems ranging from toxicity, poor efficacy, drug resistance and high cost. Thus, cheaper and less toxic treatments are necessary. From our in-house chemical library of agents against Trypanosoma cruzi the most relevant N-oxide-containing heterocycles were selected for mode of action and type of death studies. Also included in these studies were two active nitrofuranes. Epimastigotes of T. cruzi were used as the biological model in this study. The metabolic profile was studied by 1H NMR in association with the MTT assay. Excreted catabolites data, using 1H NMR spectroscopy, showed that most of the studied N-oxides were capable of decreasing both the release of succinate and acetate shedding, the compounds therefore possibly acting on mitochondria. Only quinoxalines and the nitrofurane Nf1 showed significant mitochondrial dehydrogenase inhibitions, but with different dose-time profiles. In the particular case of quinoxaline Qx2 the glucose uptake study revealed that the integrity of some pathways into the glycosome could be affected. Optic, fluorescence (TUNEL and propidium iodide) and transmission electron microscopy (TEM) were employed for type of death studies. These studies were complemented with 1H NMR to visualize mobile lipids. At low concentrations none of the selected compounds showed a positive TUNEL assay. However, both quinoxalines, one furoxan and one benzofuroxan showed a necrotic effect at high concentrations. Curiously, one furoxan, Fx1, one benzofuroxan, Bfx1, and one nitrofurane, Nf1, caused a particular phenotype, with a big cytoplasmatic vacuole being observed while the parasite was still alive. Studies of TEM and employing a protease inhibitor (3-methyladenine) suggested an autophagic phenotype for Bfx1 and Nf1 and a 'BigEye' phenotype for Fx1.
Grupo de Química Medicinal, Laboratorio de Química Orgánica, Facultad de Ciencias-Facultad de Química, Universidad de la República, Montevideo, Uruguay.
Diego
D
Benítez
Unidad de Microscopía Electrónica de Transmisión, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay.
Gabriela
G
Casanova
Facultad de Medicina, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile.
Gonzalo
G
Cabrera
Facultad de Medicina, Programa de Biología Celular y Molecular, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile.
Norbel
N
Galanti
Grupo de Química Medicinal, Laboratorio de Química Orgánica, Facultad de Ciencias-Facultad de Química, Universidad de la República, Montevideo, Uruguay.
Hugo
H
Cerecetto
Grupo de Química Medicinal, Laboratorio de Química Orgánica, Facultad de Ciencias-Facultad de Química, Universidad de la República, Montevideo, Uruguay.
Mercedes
M
González
D001343:Autophagy / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D014355:Chagas Disease / Q000469:parasitology*; D003497:Cyclic N-Oxides / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D046529:Microscopy, Electron, Transmission; D009336:Necrosis; D010641:Phenotype; D014344:Trypanocidal Agents / Q000737:chemistry / Q000494:pharmacology*; D014349:Trypanosoma cruzi / Q000187:drug effects* / Q000502:physiology / Q000648:ultrastructure
D003497:Cyclic N-Oxides; D014344:Trypanocidal Agents