Multi-Anti-Parasitic Activity of Arylidene Ketones and Thiazolidene Hydrazines against Trypanosoma cruzi and Leishmania spp

Abstract

A series of fifty arylideneketones and thiazolidenehydrazines was evaluated against Leishmania infantum and Leishmania braziliensis. Furthermore, new simplified thiazolidenehydrazine derivatives were evaluated against Trypanosoma cruzi. The cytotoxicity of the active compounds on non-infected fibroblasts or macrophages was established in vitro to evaluate the selectivity of their anti-parasitic effects. Seven thiazolidenehydrazine derivatives and ten arylideneketones had good activity against the three parasites. The IC₅₀ values for T. cruzi and Leishmania spp. ranged from 90 nM-25 µM. Eight compounds had multi-trypanocidal activity against T. cruzi and Leishmania spp. (the etiological agents of cutaneous and visceral forms). The selectivity of these active compounds was better than the three reference drugs: benznidazole, glucantime and miltefosine. They also had low toxicity when tested in vivo on zebrafish. Trying to understand the mechanism of action of these compounds, two possible molecular targets were investigated: triosephosphate isomerase and cruzipain. We also used a molecular stripping approach to elucidate the minimal structural requirements for their anti-T. cruzi activity.

Keywords: anti-T. cruzi and anti-Leishmania spp. activity; arylidene ketones; cruzipain; in vivo toxicity; thiazolidene hydrazines; triosephosphate isomerase; zebrafish.

Figure 1

Drug candidates for Chagas disease, which also are leishmanicidal compounds. These compounds have an excellent profile as drugs for Chagas disease and are easy and inexpensive to produce. (A) A culture of Vero cells infected with T. cruzi (see the cytosol full of amastigotes); (B) The same cell culture after 72 h of treatment with 5 µM HIT1 (see the cytosol without amastigotes) [12,13,19]

Figure 2

Synthetic procedures used to prepare the HIT1 derivatives (blue) and for the molecular stripping (black). RT is room temperature 25 °C, CDi is 1,1′-carbonyldiimidazole.

Figure 3

Synthetic procedures used to prepare the HIT2 derivatives (blue) and for the molecular stripping (black).

Figure 4

Molecular stripping of HIT1 for T. cruzi. In the figure, we show, using the emoticon code, the different effects on the trypanocidal activity of our compounds caused by structural changes (very good (IC₅₀ < 5 µM), good (IC₅₀ 5–25 µM), no change and bad (IC₅₀ ˃ 25 µM). The compounds codes are exactly the same from the personal codes on the Lab, GATN°, GATkN°, GATjmN°, EAN° and PgN°.

Figure 5

Molecular stripping of GAT1033 for T. cruzi. In the figure, we show using the emoticon code the different effects on the trypanocidal activity of our compounds caused by structural changes (very good (IC₅₀ < 5 µM), good (IC₅₀ 5–25 µM), no change and bad (IC₅₀ ˃ 25 µM).

Figure 6

Multi-anti-parasitic activity comparison scheme. We show using the emoticon code a qualitative comparison for the trypanocidal activities of the arylideneketones on T. cruzi, L. braziliensis and L. infantum (good IC₅₀ < 25 µM and bad IC₅₀ ˃ 25 µM).

Figure 7

Dose-response effect of GAT1033 on the curvature of the tail. Incubation concentrations were 0–300 µM for 72 h (illustrated with the brown triangle). The picture at the bottom shows a non-treated embryo at the same developmental stage.

Figure 8

Differential distribution of GAT1033 in embryos with and without chorion. The microscopy images on the left show the eye and parts of the yolk of 24-hpf zebrafish embryos. The intrinsic fluorescence of the compound was revealed using a laser scanning confocal microscope, after 18 h of incubation. The yolk (marked with *) shows a strong autofluorescence under these imaging conditions. The graph on the right shows the quantitation of fluorescence intensity (in arbitrary units AU) in treated embryos with and without chorion.

Figure 9

Bioconcentration effects of GAT1033. The bioconcentration effect can be seen at different incubation times. The embryos were incubated at 25 µM for up to 66 h. wC, with chorion; woC, without chorion. The graph shows the quantitation of the compound (in mg per embryo mg/e) in treated embryos with and without chorion.