In this research three series of substituted 1H-pyrazolo[3,4-b]pyridine phosphoramidates were synthesized and characterized by infrared, 1H, 13C, and 31P nuclear magnetic resonance (NMR) spectroscopy and high-resolution mass spectrometry. The products were obtained in good yields (67-83%) under mild conditions by nucleophilic aromatic substitution reaction of aminoalkylphosphoramidates over 4-chloro-1H-pyrazolo[3,4-b]pyridines. These compounds were evaluated as antileishmanials against Leishmania amazonensis promastigotes in vitro. Among all, compounds of a series showed expressive antileishmanial activity. Two of them emerged as the most active, with IC50 values of 6.44 ± 1.49 and 12.25 ± 0.68 µM. The cytotoxicity of this series was assessed on murine cells and presented values similar to the reference drug pentamidine.

Este artigo descreve a síntese e a atividade antileishmania de novos derivados pirazolil benzenossulfonamídicos. Estes foram elucidados por métodos espectrométricos. Alguns compostos mostraram uma atividade in vitro significativa contra Leishmania amazonensis, destacando-se o derivado 1e. Nenhum dos derivados pirazolil benzenossulfonamídicos mostraram qualquer toxicidade em macrófagos murinos.

This paper describes the synthesis and the antileishmanial activity of new pyrazolyl benzenesulfonamide derivatives. These were elucidated by spectrometric methods. Some compounds showed a significant in vitro activity against Leishmania amazonensis, highlighting the derivative 1e. These pyrazolyl benzenesulfonamide derivatives did not show any toxicity in murine macrophage.

In Leishmania amazonensis, kinetoplastid membrane protein-11 (KMP-11) expression increases during metacyclogenesis and is higher in amastigotes than in promastigotes, suggesting a role for this protein in the infection of the mammalian host. We show that the addition of KMP-11 exacerbates L. amazonensis infection in peritoneal macrophages from BALB/c mice by increasing interleukin (IL)-10 secretion and arginase activity while reducing nitric oxide (NO) production. The doses of KMP-11, the IL-10 levels and the intracellular amastigote loads were strongly, positively and significantly correlated. The increase in parasite load induced by KMP-11 was inhibited by anti-KMP-11 or anti-IL-10 neutralising antibodies, but not by isotype controls. The neutralising antibodies, but not the isotype controls, were also able to significantly decrease the parasite load in macrophages cultured without the addition of KMP-11, demonstrating that KMP-11-induced exacerbation of the infection is not dependent on the addition of exogenous KMP-11 and that the protein naturally expressed by the parasite is able to promote it. In this study, the exacerbating effect of KMP-11 on macrophage infection with Leishmania is for the first time demonstrated, implicating it as a virulence factor in L. amazonensis. The stimulation of IL-10 production and arginase activity and the inhibition of NO synthesis are likely involved in this effect.

Este trabalho compara pela primeira vez a composição química do óleo essencial das folhas de Licaria canella coletadas em duas estações climáticas. Os resultados foram comparados com os obtidos para o óleo essencial das folhas de outra espécie da família Lauraceae, Aniba canelilla, coletada no mesmo período. Ambos os óleos essenciais foram analisados por CG-DIC e CG-EM, e os resultados indicaram uma grande quantidade de benzenóides, sendo o principal constituinte em L. canella o benzoato de benzila e para A. canelilla, o 1-nitro-2-feniletano. A comparação das atividades biológicas mostrou que o óleo de L. canella (IC50 19 µg mL-1) foi mais ativo contra as cepas de Leishmania amazonensis e menos citotóxico em cultura de macrófagos do que o de A. canelilla (IC50 40 µg mL-1). Por outro lado, o óleo de L. canella exibiu uma maior citotoxicidade contra Artemia salina com uma concentração letal (CL50) igual a 5,25 µg mL-1.

This work compares the chemical composition of the essential oils from the leaves of Licaria canella collected in two different seasons. The results of this investigation were compared with the leaf essential oils of other species of the Lauraceae family, Aniba canelilla, collected at the same time. Both essential oils were analyzed by GC-FID and GC-MS. The results demonstrated a larger predominance of benzenoids, being the main constituent benzyl benzoate for L. canella and 1-nitro-2-phenylethane for A. canelilla. The comparison of the biological activities showed that L. canella (IC50 19 µg mL-1) was more active against Leishmania amazonensis strains and less cytotoxic in macrophage cultures than A. canelilla (IC50 40 µg mL-1). On the other hand, the L. canella oil displayed a higher cytotoxicity against Artemia salina with a lethal concentration (LC50), equal to 5.25 µg mL-1.

Extracts of propolis samples collected in Brazil and Bulgaria were assayed against four Leishmania species - Leishmania amazonensis, L. braziliensis, L. chagasi from the New World, and L. major from the Old World - associated to different clinical forms of leishmaniasis. The composition of the extracts has been previously characterized by high temperature high resolution gas chromatography coupled to mass spectrometry. Considering the chemical differences among the extracts and the behavior of the parasites, it was observed significant differences in the leishmanicidal activities with IC50/1 day values in the range of 2.8 to 229.3 µg/ml . An overall analysis showed that for all the species evaluated, Bulgarian extracts were more active than the ethanol Brazilian extract. As the assayed propolis extracts have their chemical composition determined it merits further investigation the effect of individual components or their combinations on each Leishmania species.

The antileishmanial activity of lapachol, isolapachol, and dihydrolapachol, along with soluble derivatives (potassium salt) and acetate was obtained. All the compounds were assayed against metacyclic promastigotes of two different species of Leishmania associated to tegumentar leishmaniasis: L. amazonensis and L. braziliensis. All compounds presented significant activity, being isolapachol acetate the most active against promastigotes, with IC50/24h = 1.6 ± 0.0 µg/ml and 3.4 ± 0.5 µg/ml for, respectively, L. amazonensis and L. braziliensis. This compound was also assayed in vivo against L. amazonensis and showed to be active. Its toxicity in vitro was also established, and at concentration similar to the IC50, no toxicity was evidenced. In all experiments, pentamidine isethionate was used as a reference drug. The present results reinforce the potential use of substituted hydroxyquinones and derivatives as promising antileishmanial drugs and suggest a continuing study within this class of compounds.

Infections due to protozoa of the genus Leishmania are a major worldwide health problem, with high endemicity in developing countries. The drugs of choice for the treatment of leishmaniasis are the pentavalent antimonials (SbV), which present renal and cardiac toxicity. Besides, the precise chemical structure and mechanism of action of these drugs are unknown up to date. In order to find new drugs against leishmaniasis, we have been studying extracts of Brazilian trees. In the present study, we have evaluated the effectiveness of an alkaloid extract of Aspidosperma ramiflorum Muell. Arg. (Apocynaceae), against the extracellular forms promastigotes of L. (L.) amazonensis and L. (V.) braziliensis. The alkaloid extract of A. ramiflorum was much more effective against L. (L.) amazonensis (LD50 < 47 µg/ml) than L. (V.) braziliensis. Based on these in vitro results against L. (L.) amazonensis new studies should be made to find the compounds with anti-leishmanial activity.

The activity of several diarylheptanoid derivatives (curcuminoids) was previously evaluated against Leishmania amazonensis promastigotes and among them the most active compound was the [1-(4-methoxy-phenyl)-7-(3,4-methoxy-4-hydroxy-phenyl)-1,6-heptadien-3, 5-dione]. This derivative was chosen to be assayed in vivo in a treatment trial. For these experiments, the curcuminoid compound was used in a concentration equivalent to the IC50/24 h, obtained from the previous study. Balb/c mice were inoculated subcutaneously in the footpad with L. amazonensis infective promastigotes and 4 weeks after the inoculation, the animals were treated with different schemes, varying from 1 to 3 doses. In all the experiments, Pentamidine Isethionate was used as reference drug under the same experimental conditions. The results showed that one dose was not enough to heal the lesion, however, with 2 and 3 doses the efficiency of the assayed compound was clear. On the other hand, treatment with Pentamidine Isethionate using the three different schemes was not satisfactory when compared to the curcuminoid derivative.

Philander frenata e Didelphis marsupialis mantém Trypanosoma cruzi sem desenvolver aparentemente nenhuma doença. Ao contrário de Didelphis marsupialis, Philander frenata mantém subpopulações do grupo T. cruzi II. Aqui, nós comparamos a resposta imune humoral de dois didelfídeos natural e experimentalmente infectados com o grupo T. cruzi II, empregando as técnicas de SDS-PAGE/Western blot e por um método de imunofluorescência indireta. Também estudamos os padrões histopatológicos de P. frenata infectado natural e experimentalmente por T. cruzi. O soro de P. frenata reconheceu mais antígenos que o de D. marsupialis. Polipeptídeos de 66 e 90kDa foram os antígenos mais reconhecidos por ambas espécies nas frações enriquecidas de membranas solúveis. P. frenata reconheceu intensamente o antígeno de 45kDa. Nossos resultados indicam que: não existem diferenças quantitativas e qualitativas nas fases subpatente e patente no padrão de reconhecimento de P. frenata; as diferenças no padrão de reconhecimento de antígenos de parasitas pelos soros de P. frenata e D. marsupialis sugerem que provavelmente essas espécies "aprenderam" a viver em harmonia com T. cruzi por estratégias distintas; embora P. frenata não apresente doença aparente, lesões tissulares tendem a ser mais severas do que as descritas para D. marsupialis; ambos didelfídeos provavelmente adquiriram a infecção por T. cruzi depois de sua divergência evolucionária.

Philander frenata and Didelphis marsupialis harbor parasitism by Trypanosoma cruzi without developing any apparent disease and on the contrary to D. marsupialis, P. frenata maintains parasitism by T. cruzi II subpopulations. Here we compared the humoral immune response of the two didelphids naturally and experimentally infected with T. cruzi II group, employing SDS-PAGE/Western blot techniques and by an Indirect immunofluorescence assay. We also studied the histopathological pattern of naturally and experimentally infected P. frenata with T. cruzi. P. frenata sera recognized more antigens than D. marsupialis, and the recognition pattern did not show any change over the course of the follow up of both didelphid species. Polypeptides of 66 and 90kDa were the most prominent antigens recognized by both species in the soluble and enriched membrane fractions. P. frenata recognized intensely also a 45kDa antigen. Our findings indicate that: 1) there were no quantitative or qualitative differences in the patent or subpatent phases in the recognition pattern of P. frenata; 2) the significant differences in the recognition pattern of parasitic antigens by P. frenata and D. marsupialis sera suggest that they probably "learned" to live in harmony with T. cruzi by different strategies; 3) although P. frenata do not display apparent disease, tissular lesions tended to be more severe than has been described in D. marsupialis; and 4) Both didelphids probably acquired infection by T. cruzi after their evolutionary divergence.

In a previous work we demonstrated that diarylheptanoids extracted from Centrolobium sclerophyllum are very active against Leishmania amazonensis promastigotes. In order to continue our studies with these class of compounds, we decided to evaluate the activity of several diarylheptanoids derived from curcumin (diferuloyl methane) against the extracellular form (promastigotes) of L. amazonensis. Furthermore, an experiment against the intracellular form of the parasite (amastigotes) was carried out, comparing the most active compound among the curcumin derivatives (the methylcurcumin) with des-O-methylcentrolobine, the most active diarylheptanoid derived from C. sclerophyllum.

Immunoblot analysis was used to investigate antigenic differences among clinical isolates of Leishmania amazonensis and their role in the etiology of the diseases. Western blots of promastigote homogenates were analyzed with either monoclonal antibodies (MAbs) specific for the L. mexicana complex (M-4, M-6, M-9 and M-11) or polyclonal sera from L. amazonensis infected patients with the various forms of clinical disease. In the case of the MAbs, no significant variation was observed among the strains of L. amazonensis, isolated from cases of cutaneous leishmaniasis (CL), mucocutaneous leishmaniasis (MCL), diffuse cutaneous leishmaniasis (DCL), visceral leishmaniasis (VL) or post kala-azar dermal leishmaniasis (PKDL), in either the relative morbility (Mr) or the quantitative amount (intensity) of the antigenic determinats. In the case of the sera of the infected patients, the patterns of antigenic reactivity of these strains revealed that, despite showing the presence of shared antigens, differences were observed between some of the antigenic components of the various isolates of L. amazonensis that were recognized by a single serum. Differences were also demonstrated between the antigenic determinants of a single isolate of L. amazonensis that were recognized by the different patient's sera. No apparent association was consistently found, however, between the Mr components identified in these isolates and clinical form of the disease or the geographical area of isolation. In addition, the spectrum of antigens recognized by the sera from patients with the same clinical form were not identical; although in some instances, similar Mr antigens were shared. These results indicate that isolates of L. amazonensis are not antigenically identical (homogeneous) and that the immune responses (antibodies) observed among infected patients are heterogeneous.

Um método de fracionamento subcelular, previamente desenvolvido para Trypanosoma cruzi, foi aplicado para isolar a membrana plasmática de promastigotas de Leishmania mexicana amazonensis. As células, após turgimento em meio hipotônico, foram rompidas na presença de um detergente não iônico e a fração de membrana isolada por centrifugação diferencial. A microscopia eletrônica mostrou consistir a fração de fragmentos de membrana plasmática associados com microtúbulos subpeliculares. Foi também mostrado que esta fração era capaz de induzir resposta celular em camundongos.

A cell fractionation procedure previously developed for Trypanosoma cruzi was applied to isolated the plasma membrane of promastigotes of Leishania mexicana amazonensis. The cell, swollen in an hypotonic mediun, were disrupted in the presence of a nonionic detergent and the membrane fraction isolated by differencial centrifugation. Electron microscopy showed that the fraction consisted of pieces of the plasma membrane associated with subpellicular microtubules. It was also shown that this fraction is able to induce cell-mediated immune response in mice.