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Laura C Laurella,
Fernanda M Frank,
Andrea Sarquiz,
María R Alonso,
Gustavo Giberti,
Lucia Cavallaro,
Cesar A Catalán, Silvia I Cazorla,
Emilio Malchiodi,
Virginia S Martino,
Valeria P Sülsen
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ABSTRACT: The aim of this study was to investigate the antiprotozoal and antiviral activities of four Argentinean Mikania species. The organic and aqueous extracts of Mikania micrantha, M. parodii, M. periplocifolia, and M. cordifolia were tested on Trypanosoma cruzi epimastigotes, Leishmania braziliensis promastigotes, and dengue virus type 2. The organic extract of M. micrantha was the most active against T. cruzi and L. braziliensis exhibiting a growth inhibition of 77.6 ± 4.5% and 84.9 ± 6.1%, respectively, at a concentration of 10 μg/ml. The bioguided fractionation of M. micrantha organic extract led to the identification of two active fractions. The chromatographic profile and infrared analysis of these fractions revealed the presence of sesquiterpene lactones. None of the tested extracts were active against dengue virus type 2.
TheScientificWorldJOURNAL 01/2012; 2012:121253. · 1.66 Impact Factor
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ABSTRACT: In this study, the antiprotozoal activity of the sesquiterpene lactone psilostachyin C was investigated. This natural compound was isolated from Ambrosia scabra by bioassay-guided fractionation and was identified by spectroscopic techniques. Psilostachyin C exerted in vitro trypanocidal activity against Trypanosoma cruzi epimastigotes, trypomastigotes and amastigotes, with 50% inhibitory concentration (IC(50)) values of 0.6, 3.5 and 0.9 μg/mL, respectively, and displayed less cytotoxicity against mammalian cells, with a 50% cytotoxic concentration (CC(50)) of 87.5 μg/mL. Interestingly, this compound induced ultrastructural alterations, as seen by transmission electron microscopy, in which vacuolisation and a structural appearance resembling multivesicular bodies were observed even at a concentration as low as 0.2 μg/mL. In an in vivo assay, a significant reduction in the number of circulating parasites was found in T. cruzi-infected mice treated with psilostachyin C for 5 days compared with untreated mice (7.4 ± 1.2 × 10(5)parasites/mL vs. 12.8 ± 2.0 × 10(5)parasites/mL) at the peak of parasitaemia. According to these results, psilostachyin C may be considered a promising template for the design of novel trypanocidal agents. In addition, psilostachyin C inhibited the growth of Leishmania mexicana and Leishmania amazonensis promastigotes (IC(50)=1.2 μg/mL and 1.5 μg/mL, respectively).
International journal of antimicrobial agents 06/2011; 37(6):536-43. · 3.03 Impact Factor
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ABSTRACT: Research and development of new drugs effective in the treatment of Trypanosoma cruzi infections are a real need for the 16 million people infected in the Americas. In a previous work, a quinoline derivative substituted by a 2-piperidylmethyl moiety showed to be active against Chagas disease and was considered a lead compound for further optimization. A series of ten analogous derivatives were tested against epimastigotes as a first approach. In view of their promising results, six of them were evaluated against the blood and intracellular replicative forms of the parasite in humans. Among them, compound 12 which possesses a 6-acetamidohexylamino substituent showed remarkable improvement in activity against epimastigotes, trypomastigotes and amastigotes compared with the structure lead, as well as a good selectivity index for the two parasite stages present in humans. In addition, treatment of infected mice with compound 12 induced a significant reduction in parasitemia compared with non-treated mice. Molecular modeling studies were performed by computational methods in order to elucidate the factors determining these experimental bioactivities.
European journal of medicinal chemistry 05/2011; 46(9):3696-703. · 3.27 Impact Factor
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ABSTRACT: Despite the strong immune responses elicited after natural infection with Trypanosoma cruzi or vaccination against it, parasite survival suggests that these responses are insufficient or inherently inadequate. T. cruzi contains a major cystein proteinase, cruzipain, which has a catalytic N-terminal domain and a C-terminal extension. Immunizations that employed recombinant cruzipain or its N- and C-terminal domains allowed evaluation of the ability of cruzipain to circumvent responses against the catalytic domain. This phenomenon is not a property of the parasite but of cruzipain itself, because recombinant cruzipain triggers a response similar to that of cruzipain during natural or experimental infection. Cruzipain is not the only antigen with a highly immunogenic region of unknown function that somehow protects an essential domain for parasite survival. However, our studies show that this can be reverted by using the N-terminal domain as a tailored immunogen able to redirect host responses to provide enhanced protection.
The Journal of Infectious Diseases 07/2010; 202(1):136-44. · 6.41 Impact Factor
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ABSTRACT: Cells of monocyte/macrophage lineage are one of the major targets of HIV-1 infection and serve as reservoirs for viral persistence in vivo. These cells are also the target of the protozoa Trypanosoma cruzi, the causative agent of Chagas disease, being one of the most important endemic protozoonoses in Latin America. It has been demonstrated in vitro that co-infection with other pathogens can modulate HIV replication. However, no studies at cellular level have suggested an interaction between T. cruzi and HIV-1 to date.
By using a fully replicative wild-type virus, our study showed that T. cruzi inhibits HIV-1 antigen production by nearly 100% (p<0.001) in monocyte-derived macrophages (MDM). In different infection schemes with luciferase-reporter VSV-G or BaL pseudotyped HIV-1 and trypomastigotes, T. cruzi induced a significant reduction of luciferase level for both pseudotypes in all the infection schemes (p<0.001), T. cruzi-HIV (>99%) being stronger than HIV-T. cruzi (approximately 90% for BaL and approximately 85% for VSV-G) infection. In MDM with established HIV-1 infection, T. cruzi significantly inhibited luciferate activity (p<0.01). By quantifying R-U5 and U5-gag transcripts by real time PCR, our study showed the expression of both transcripts significantly diminished in the presence of trypomastigotes (p<0.05). Thus, T. cruzi inhibits viral post-integration steps, early post-entry steps and entry into MDM. Trypomastigotes also caused a approximately 60-70% decrease of surface CCR5 expression on MDM. Multiplication of T. cruzi inside the MDM does not seem to be required for inhibiting HIV-1 replication since soluble factors secreted by trypomastigotes have shown similar effects. Moreover, the major parasite antigen cruzipain, which is secreted by the trypomastigote form, was able to inhibit viral production in MDM over 90% (p<0.01).
Our study showed that T. cruzi inhibits HIV-1 replication at several replication stages in macrophages, a major cell target for both pathogens.
PLoS ONE 01/2009; 4(12):e8246. · 4.09 Impact Factor
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ABSTRACT: Bioassay-guided fractionation of the organic extract of Ambrosia tenuifolia Sprengel (Asteraceae) led to the isolation of two bioactive sesquiterpene lactones with significant trypanocidal and leishmanicidal activities. By spectroscopic methods ((1)H- and (13)C-nuclear magnetic resonance, distortionless enhancement by polarization transfer, correlated spectroscopy, heteronuclear multiple-quantum coherence, electron impact-mass spectrometry, and infrared spectroscopy), these compounds were identified as psilostachyin and peruvin. Both compounds showed a marked in vitro trypanocidal activity against Trypanosoma cruzi epimastigotes with 50% inhibitory concentration (IC(50)) values of less than 2 microg/ml. Psilostachyin exerted a significant in vitro activity against the trypomastigote forms of T. cruzi (IC(50), 0.76 microg/ml) and was selected for in vivo testing. Psilostachyin-treated mice had a survival of 100% and lower parasitemia values than control mice. Both compounds were also tested on Leishmania sp. promastigotes: psilostachyin (IC(50), 0.12 microg/ml) and peruvin (IC(50), 0.39 microg/ml) exerted significant leishmanicidal activities. This is the first time that the trypanocidal and leishmanicidal activities of these compounds have been reported. The selectivity index (SI) was employed to evaluate the cytotoxic effect of lactones on T lymphocytes. Although the SIs of both compounds were high for T. cruzi epimastigotes, psilostachyin was more selective against trypomastigotes (SI, 33.8) while peruvin showed no specificity for this parasite. Both compounds presented high selectivity for Leishmania spp. The results shown herein suggest that psilostachyin and peruvin could be considered potential candidates for the development of new antiprotozoal agents against Chagas' disease and leishmaniasis.
Antimicrobial Agents and Chemotherapy 08/2008; 52(7):2415-9. · 4.84 Impact Factor
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ABSTRACT: Cruzipain (Cz), a key Trypanosoma cruzi enzyme, is a main candidate antigen for vaccines against Chagas' disease. We evaluated a vaccination protocol based on intradermal priming with recombinant Cz and intranasal boosting with rCz co-administered with a derivative of the TLR2/6 agonist MALP-2. Vaccination triggered strong systemic and mucosal antibody responses, and a vigorous cell-mediated immunity characterized by lymphoproliferation, DTH reactivity and IFN-gamma production. The immune responses protected against a lethal trypomastigote challenge and, upon sub-lethal infection, immunized mice showed reduction of tissue damage and normal enzymatic markers of muscle injury. This prime-boost regimen appears promising for further development, since warranted survival, provided efficient control of parasite load and restricted inflammatory myopathy.
Vaccine 05/2008; 26(16):1999-2009. · 3.77 Impact Factor
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ABSTRACT: To stimulate both local and systemic immune responses against Trypanosoma cruzi, Salmonella enterica serovar Typhimurium aroA was exploited as a DNA delivery system for cruzipain (SCz). In a murine model we compared SCz alone (GI) or coadministered with Salmonella carrying a plasmid encoding granulocyte-macrophage colony-stimulating factor (GII), as well as protocols in which SCz priming was followed by boosting with recombinant cruzipain (rCz) admixed with either CpG-ODN (GIII) or MALP-2, a synthetic derivative of a macrophage-activating lipopeptide of 2 kDa from Mycoplasma fermentans (GIV). The results showed that protocols that included four oral doses of SCz (GI) elicited mainly a mucosal response characterized by immunoglobulin A (IgA) secretion and proliferation of gut-associated lymphoid tissue cells, with weak systemic responses. In contrast, the protocol that included a boost with rCz plus CpG (GIII) triggered stronger systemic responses in terms of Cz-specific serum IgG titers, splenocyte proliferation, gamma interferon (IFN-gamma) secretion, and delayed-type hypersensitivity response. Trypomastigote challenge of vaccinated mice resulted in significantly lower levels of parasitemia compared to controls. Protection was abolished by depletion of either CD4+ or CD8+ T cells. Parasite control was also evident from the reduction of tissue damage, as revealed by histopathologic studies and serum levels of enzymes that are markers of muscle injury in chronic Chagas' disease (i.e., creatine kinase, aspartate aminotransferase, and lactate dehydrogenase). Enhanced release of IFN-gamma and interleukin-2 was observed in GI and GII upon restimulation of splenocytes in the nonparasitic phase of infection. Our results indicate that Salmonella-mediated delivery of Cz-DNA by itself promotes the elicitation of an immune response that controls T. cruzi infection, thereby reducing parasite loads and subsequent damage to muscle tissues.
Infection and immunity 02/2008; 76(1):324-33. · 4.21 Impact Factor
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ABSTRACT: In vitro trypanocidal and leishmanicidal activities of the flavonoids hispidulin, from Ambrosia tenuifolia, and santin, from Eupatorium buniifolium, are reported. A sensitive technique that takes advantage of ((3)H)thymidine uptake by dividing trypanosomatids has been adjusted for quantification of the parasiticidal effect of the natural products. The IC(50) values for hispidulin and santin on Trypanosoma cruzi epimastigotes were 46.7 and 47.4 muM, respectively. On trypomastigotes, the IC(50) values were 62.3 microM for hispidulin and 42.1 microM for santin. Hispidulin was more active than santin on promastigotes of Leishmania mexicana (IC(50) = 6.0 microM versus 32.5 microM). No cytotoxic activity was observed on lymphoid cells, making hispidulin and santin potential lead compounds for the development of new natural drugs. This is the first report on the trypanocidal and leishmanicidal activities of these flavonoids and on the presence of santin in E. buniifolium.
The American journal of tropical medicine and hygiene 11/2007; 77(4):654-9. · 2.59 Impact Factor
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ABSTRACT: The crucial role played by Ag163B6/cruzipain, the major cystein proteinase of Trypanosoma cruzi, in the process of parasite internalization into mammalian cells and IgG hydrolysis, signals this antigen as a potential target for raising a protective immune response against Chagas' disease. On the other hand, synthetic oligodeoxynucleotides containing CpG-motifs (CpG-ODN) are capable of driving immunity toward a Th1 bias. Considering the importance of Th1 mechanisms in resistance against this intracellular parasite, we analyzed the ability of Ag163B6/cruzipain plus CpG-ODN to induce immunoprotection against a lethal challenge with trypomastigotes. Mice were immunized with Ag163B6+CpG-ODN showing high specific antibody titers, mostly IgG2a. Spleen cells from these mice strongly proliferated and presented significant increase of IL-2 and IFN-gamma concentrations in their supernatant upon antigen stimulation. Trypomastigote challenge rendered elevated parasitemia and mortality in all control groups, meanwhile Ag163B6+CpG-ODN mice displayed the lowest level of blood parasites and 100% survival to acute infection. Besides, we demonstrated that other parasite antigens introduced into mice when challenged, and consequently never seen before by the immune system, also elicited a Th1 immune response. Taken together, these results plus others provide the basis for the design of a multicomponent anti-T. cruzi vaccine which may ultimately be used not only to protect humans at risk of infection, but also may alleviate or prevent the pathogenic responses characteristic of chronic Chagas' disease by reducing or perhaps eliminating tissue parasites from infected patients.
Vaccine 01/2004; 22(1):77-86. · 3.77 Impact Factor
