1,4-Diamino-2-butanone, a putrescine analogue, promotes redox imbalance in Trypanosoma cruzi and mammalian cells.

The putrescine analogue 1,4-diamino-2-butanone (DAB) is highly toxic to various microorganisms, including Trypanosoma cruzi. Similar to other α-aminocarbonyl metabolites, DAB exhibits pro-oxidant properties. DAB undergoes metal-catalyzed oxidation yielding H(2)O(2), NH(4)(+) ion, and a highly toxic α-oxoaldehyde. In vitro, DAB decreases mammalian cell viability associated with changes in redox balance. Here, we aim to clarify the DAB pro-oxidant effects on trypomastigotes and on intracellular T. cruzi amastigotes. DAB (0.05-5 mM) exposure in trypomastigotes, the infective stage of T. cruzi, leads to a decline in parasite viability (IC(50)c.a. 0.2 mM DAB; 4 h incubation), changes in morphology, thiol redox imbalance, and increased TcSOD activity. Medium supplementation with catalase (2.5 µM) protects trypomastigotes against DAB toxicity, while host cell invasion by trypomastigotes is hampered by DAB. Additionally, intracellular amastigotes are susceptible to DAB toxicity. Furthermore, pre-treatment with 100-500 µM buthionine sulfoximine (BSO) of LLC-MK2 potentiates DAB cytotoxicity, whereas 5 mM N-acetyl-cysteine (NAC) protects cells from oxidative stress. Together, these data support the hypothesis that redox imbalance contributes to DAB cytotoxicity in both T. cruzi and mammalian host cells.

Putrescine analogue cytotoxicity against Trypanosoma cruzi.

Trypanosoma cruzi is the etiological agent of American trypanosomiasis. Most of the available data on trypanosomatid parasites were obtained from African trypanosomes. Parasitic protozoa polyamine metabolism and transport pathways comprise valuable targets for chemotherapy. T. cruzi cannot synthesize putrescine, but its uptake from the extracellular milieu can promote parasite survival. Nevertheless, little is known about the cell biology of this diamine in T. cruzi. Here we notice that the putrescine analogue 1,4-diamino-2-butanone (DAB) inhibited T. cruzi epimastigotes' in vitro proliferation and produced remarkable mitochondrial destruction and cell architecture disorganization, as assessed by transmission electron microscopy. Mitochondrial damage was confirmed by MTT reduction. We decided to analyze the oxidative stress undergone by DAB-treated parasites. Thiobarbituric-acid-reactive substances were measured to assess lipid peroxidation. Analogue effects were dose-dependent; 5 mM DAB only slightly enhanced peroxidation, whereas 10 mM DAB significantly (P < 0.05) diminished it. These data indicate that putrescine uptake by this diamine auxotrophic parasite may be important for epimastigote axenic growth and cellular organization.