Antiparasitic effect of a fraction enriched in tight-binding protease inhibitors isolated from the Caribbean coral Plexaura homomalla.

Malaria and American Trypanosomiasis constitute major global health problems. The continued emergence and spreading of resistant strains and the limited efficacy and/or safety of currently available therapeutic agents require a constant search for new sources of antiparasitic compounds. In the present study, a fraction enriched in tight-binding protease inhibitors was isolated from the Caribbean coral Plexaura homomalla (Esper, 1792), functionally characterized and tested for their antiparasitic activity against Trypanosoma cruzi and Plasmodium falciparum. The resultant fraction was chromatographically enriched in tight-binding inhibitors active against Papain-like cysteine peptidases (92%) and Pepsin-like aspartyl peptidases (8%). Globally, the inhibitors present in the enriched fraction showed no competition with substrates and apparent Ki values of 1.99 and 4.81nM for Falcipain 2 and Cruzipain, the major cysteine peptidases from P. falciparum and T. cruzi, respectively. The inhibitor-enriched fraction showed promising antiparasitic activity in cultures. It reduced the growth of the chloroquine-resistant P. falciparum strain Dd2 (IC50=0.46µM) and promoted the apparent accumulation of trophozoites, both consistent with a blockade in the hemoglobin degradation pathway. At sub-micromolar concentrations, the inhibitor-enriched fraction reduced the infection of VERO cells by T. cruzi (CL Brener clone) trypomastigotes and interfered with intracellular differentiation and/or replication of the parasites. This study provides new scientific evidence that confirms P. homomalla as an excellent source of tight-biding protease inhibitors for different proteases with biomedical relevance, and suggests that either the individual inhibitors or the enriched fraction itself could be valuable as antiparasitic compounds.

Molecular diversity of the Trypanosoma cruzi TcSMUG family of mucin genes and proteins.

The surface of the protozoan Trypanosoma cruzi is covered by a dense coat of mucin-type glycoconjugates, which make a pivotal contribution to parasite protection and host immune evasion. Their importance is further underscored by the presence of >1000 mucin-like genes in the parasite genome. In the present study we demonstrate that one such group of genes, termed TcSMUG L, codes for previously unrecognized mucin-type glycoconjugates anchored to and secreted from the surface of insect-dwelling epimastigotes. These features are supported by the in vivo tracing and characterization of endogenous TcSMUG L products and recombinant tagged molecules expressed by transfected parasites. Besides displaying substantial homology to TcSMUG S products, which provide the scaffold for the major Gp35/50 mucins also present in insect-dwelling stages of the T. cruzi lifecycle, TcSMUG L products display unique structural and functional features, including being completely refractory to sialylation by parasite trans-sialidases. Although quantitative real time-PCR and gene sequencing analyses indicate a high degree of genomic conservation across the T. cruzi species, TcSMUG L product expression and processing is quite variable among different parasite isolates.

Furoxan-, alkylnitrate-derivatives and related compounds as anti-trypanosomatid agents: mechanism of action studies.

A series of over a hundred furoxans, alkylnitrates and related compounds were studied as growth inhibitors of the two major kinetoplastids of Latin America, Trypanosoma cruziand Leishmania spp., in in vitro assays. The most active compounds showed 50% inhibitory doses of the same order of that of Nifurtimox and Miltefosine, reference drugs used to treat Chagas Disease and Leishmaniasis respectively. Among the studied compounds derivative 4, presenting excellent inhibitory activity against the tryposmastigote and amastigote forms of T. cruzi, has emerged as a lead compound. Mechanism of action seems to involve mitochondrial dehydrogenases as a distinct effect with respect to Nifurtimox. Excreted metabolites, studied by NMR, showed a significant decrease in succinate, confirming the observed effect on the mitochrondrial dehydrogenases.

New trypanocidal hybrid compounds from the association of hydrazone moieties and benzofuroxan heterocycle.

Hybrid compounds containing hydrazones and benzofuroxan pharmacophores were designed as potential Trypanosoma cruzi-enzyme inhibitors. The majority of the designed compounds was successfully synthesized and biologically evaluated displaying remarkable in vitro activity against different strains of T. cruzi. Unspecific cytotoxicity was evaluated using mouse macrophages, displaying isothiosemicarbazone 10 and thiosemicarbazone 12 selectivity indexes (macrophage/parasite) of 21 and 27, respectively. In addition, the mode of anti-trypanosomal action of the derivatives was investigated. Some of these derivatives were moderate inhibitors of cysteinyl active site enzymes of T. cruzi, cruzipain and trypanothione reductase. ESR experiments using T. cruzi microsomal fraction suggest that the main mechanism of action of the trypanocidal effects is the production of oxidative stress into the parasite.

The protein family TcTASV-C is a novel Trypanosoma cruzi virulence factor secreted in extracellular vesicles by trypomastigotes and highly expressed in bloodstream forms.

TcTASV-C is a protein family of about 15 members that is expressed only in the trypomastigote stage of Trypanosoma cruzi. We have previously shown that TcTASV-C is located at the parasite surface and secreted to the medium. Here we report that the expression of different TcTASV-C genes occurs simultaneously at the trypomastigote stage and while some secreted and parasite-associated products are found in both fractions, others are different. Secreted TcTASV-C are mainly shedded through trypomastigote extracellular vesicles, of which they are an abundant constituent, despite its scarce expression on culture-derived trypomastigotes. In contrast, TcTASV-C is highly expressed in bloodstream trypomastigotes; its upregulation in bloodstream parasites was observed in different T. cruzi strains and was specific for TcTASV-C, suggesting that some host-molecules trigger TcTASV-C expression. TcTASV-C is also strongly secreted by bloodstream parasites. A DNA prime-protein boost immunization scheme with TcTASV-C was only partially effective to control the infection in mice challenged with a highly virulent T. cruzi strain. Vaccination triggered a strong humoral response that delayed the appearance of bloodstream trypomastigotes at the early phase of the infection. Linear epitopes recognized by vaccinated mice were mapped within the TcTASV-C family motif, suggesting that blockade of secreted TcTASV-C impacts on the settlement of infection. Furthermore, although experimental and naturally T. cruzi-infected hosts did not react with antigens from extracellular vesicles, vaccinated and challenged mice recognized not only TcTASV-C but also other vesicle-antigens. We hypothesize that TcTASV-C is involved in the establishment of the initial T. cruzi infection in the mammalian host. Altogether, these results point towards TcTASV-C as a novel secreted virulence factor of T. cruzi trypomastigotes.

In vivo anti-Chagas vinylthio-, vinylsulfinyl-, and vinylsulfonylbenzofuroxan derivatives.

New benzofuroxans were developed and studied as antiproliferative Trypanosoma cruzi agents. Compounds displayed remarkable in vitro activities against different strains, Tulahuen 2, CL Brener and Y. Its unspecific cytotoxicity was evaluated using human macrophages being not toxic at a concentration at least 8 times, and until 250 times, that of its T. cruzi IC50. Some biochemical pathways were studied, namely parasite respiration, cysteinyl active site enzymes and reaction with glutathione, as target for the mechanism of action. Not only T. cruzi respiration but also Cruzipain or trypanothione reductase were not affected, however the most active derivatives, the vinylsulfinyl- and vinylsulfonyl-containing benzofuroxans, react with glutathione in a redox pathway. Furthermore, the compounds showed good in vivo activities when they were studied in an acute murine model of Chagas' disease. The compounds were able to reduce the parasite loads of animals with fully established T. cruzi infections.

Colgajo en filete como tratamiento de carcinoma basocelular recidivado / Fillet flap as treatment of recurrent basal cell carcinoma

El carcinoma basocelular (CBC) es el tumor maligno de piel con el que más frecuentemente se enfrenta el cirujano plástico, y los CBC recidivados se presentan como un reto en cuanto a su resolución. Por su parte, los queloides que resultan de un proceso patológico de cicatrización tienen múltiples alternativas para su tratamiento. Se describe la versatilidad del colgajo en filete como tratamiento de un CBC recidivado retroauricular, a través de la presentación de un caso clínico

Basal cell carcinoma ( BCC) is the malignant skin tumor which most frequently is a challenge to the plastic surgeon, and basically the recurrent BCC shows a challenge in terms of resolution. On the other hand, keloids are a consequence of a disease healing process. However, these have multiple choices for treatment. As the versatility of the fillet flap described as treatment of recurrent basal cell carcinoma BCC, by through the presentation of a case report.

Synthesis of 2-hydrazolyl-4-thiazolidinones based on multicomponent reactions and biological evaluation against Trypanosoma Cruzi.

A series of 18 novel 2-hydrazolyl-4-thiazolidinones-5-carboxylic acids, amides and 5,6-α,ß-unsaturated esters were synthesized, and their in vitro activity on cruzipain and T. cruzi epimastigotes was determined. Some agents show activity at 37 µm concentration in the enzyme assay. Computational tools and docking were used to correlate the biological response with the physicochemical parameters of the compounds and their cruzipain inhibitory effects.

Second generation of 2H-benzimidazole 1,3-dioxide derivatives as anti-trypanosomatid agents: synthesis, biological evaluation, and mode of action studies.

Exploring the influence of different substitution patterns of 2H-benzimidazole 1,3-dioxide derivatives (BzNO) we prepared fifteen new derivatives. Initially the BzNO were tested against Trypanosoma cruzi Tulahuen 2 strain epimastigote form rendering very potent anti-T. cruzi agents. Moreover, the BzNO were able to inhibit the growth of virulent and resistant to Benznidazole strains (CL Brener clone, Colombiana, and Y strains) and to Leishmania braziliensis. Interestingly, BzNO exhibited very high selectivity index and particularly the spiro-BzNO 13 provokes an important diminution of amastigotes in Vero cells. Besides, it was found a diminution of acetate and glycine as excreted metabolites but without increase of parasite glucose uptake indicating that the glycosome is probably not involucrate in the 2H-benzimidazole 1,3-dioxides mechanism of action.