Assessment of in vitro and in vivo effect of Quercetin 3-Glucoside, Oxyresveratrol and Quercetin O-Hexoside against Leishmania tropica

Abstract The aim was to scrutinize the in vivo and in vitro activities against Leishmania tropica with compounds of Oxyresveratrol, Quercetin O-Hexoside, and Quercetin 3-Glucoside. The in vitro outcomes against Leishmania were analyzed for 24-48 hours on L. tropica KWH23 promastigotes with compounds materials having 50 - 200 µg/mL concentration with negative control and standard drug Amphotericin B. The compounds were analyzed in L. tropica infected BALB/c mice against Leishmania tropica. The Quercetin 3-Glucoside shows mean inhibition of extracellular promastigotes after 48 hours at 50, 100, 150, 200 µg/mL were 91.02 ± 0.12, 94.50 ± 0.07, 96.15 ± 0.17 and 97.01 ± 0.08 % respectively. In BALB/c mice, the intracellular amastigotes were 91% cured at 200 µg/mL and mean lesion size decreased to 0.41 ± 0.21 mm (p < 0.01). The result shows that Quercetin 3-Glucoside possesses significant anti-leishmanial activity.

Planejamento e desenvolvimento de novos compostos com atividade frente a Leishmania spp: Síntese, avaliação da atividade e toxicidade de derivados 5-nitro-2-furfurilidênicos e estudos de relações estrutura-atividade / Design of new compounds against Leishmania spp: synthesis, biological evaluation and toxicity of 5-nitro-2-furfurylidene derivates and structure-activity relationship studies

A leishmaniose é uma zoonose de ampla distribuição mundial, causada pelos parasitas tripanossomatídeos do gênero Leishmania. Infelizmente, o arsenal terapêutico disponível é precário, mas vê-se crescente o interesse científico pela busca do potencial de derivados nitroheterocíclicos como alternativas terapêuticas. Nesse contexto, este trabalho analisou o potencial de derivados 5-nitro-2-furfurilidênicos contra diferentes cepas de Leishmania, assim como investigou um possível modo de ação para esta classe de nitrocompostos. Para tal, a quimioteca foi sintetizada de acordo com publicações prévias do grupo. O potencial de inibição de crescimento das culturas de promastigotas de L. (L.) infantum (Linf) e L. (L.) major (Lmaj) foi determinado, utilizando miltefosina (MILT) (Linf - IC50: 8,28±0,33 µM), anfotericina B (AMB) (Linf - IC50: 0,02±0,002 µM) e nifurtimox (NFX) (Lmaj - IC50: 3,5±0,09 µM) como referência. A maioria dos compostos apresentaram maior potencial que as referênias, destacando o composto 40 (Linf - IC50: 0,2±0,019 µM/ Lmaj - IC50: 0,087 ± 0,001 µM) como mais eficaz. Contra as formas amastigotas intracelulares, para Linf os compostos 40, 13 e 15 foram mais eficazes em reduzir a carga parasitária dos macrófagos infectados que fármacos de referência. Para Lmajor, o composto 40 (IC50: 0,006 ± 0,0003 µM) foi mais ativo que o NFX (IC50: 2,15 ± 0,01 µM). Também foi determinada a atividade da quimioteca frente a enzima nitrorredutase (NTR1), utilizando cepas de T. brucei superexpressantes de NTR1, e os compostos analisados foram até 18 vezes mais eficazes que à cepa wild-type. Ademais, a partir da análise exploratória de dados por análise de componentes principais (PCA) e de grupamentos hierárquicos (HCA), foi reconhecida a influência das propriedades relacionadas com o equilíbrio hidrófilo-lipófilo e da natureza estérica/geométrica das moléculas para atividade anti-Leishmania

Leishmaniasis is a worldwide zoonosis caused by trypanosomatid parasites of the genus Leishmania. Unfortunately, the available therapeutic arsenal is precarious, but there is growing scientific interest in searching the potential of nitroheterocyclic derivatives as therapeutic alternatives. In this context, this work analyzed the potential of 5-nitro-2-furfurylidene derivatives against different Leishmania strains, as well as investigated the potential mode of action for this nitro compounds class. To this end, the chemolibrary was synthesized according to our group's previous publications. The growth inhibitory potential potential for promastigote cultures of L. (L.) infantum (Linf) and L. (L.) major (Lmaj) was determined using miltefosine (MILT) (Linf - IC50: 8.28±0.33 µM), amphotericin B (AMB) (Linf - IC50: 0.02±0.002 µM) and nifurtimox (NFX) (Lmaj - IC50: 3.5±0.09 µM) as reference. Most of the compounds were more potent than the references, highlighting compound 40 (Linf - IC50: 0.2±0.019 µM/ Lmaj - IC50: 0.087 ± 0.001 µM) as the most effective. Against intracellular amastigote, for Linf, compounds 40, 13 and 15 were more effective in reducing the parasite load of infected macrophages than reference drugs. For Lmajor, compound 40 (IC50: 0.006 ± 0.0003 µM) was more active than NFX (IC50: 2.15 ± 0.01 µM). The activity against nitroreductase (NTR1) enzyme was determined using overexpressing NTR1 mutant T. brucei strains, and the analyzed compounds were up to 18 times more effective than wild-type. Furthermore, exploratory data analysis using principal component analysis (PCA) and hierarchical clustering (HCA) methods were used. The influence of properties related to the hydrophiliclipophilic balance and the steric/geometric nature of the molecules was associated with the anti-Leishmanial activity

Evaluation of anti-leishmanial activity of artemisinin combined with amphotericin B or miltefosine in Leishmania donovani promastigotes.

Background: The increasing incidence of drug resistance in Leishmaniasis necessitates evaluation of combination chemotherapy. Miltefosine and amphotericin B are established anti-leishmanial drugs, while artemisinin has shown significant leishmanicidal activity in experimental models. In this study, we have evaluated the additive/synergistic effect of artemisinin with amphotericin B or miltefosine. Methods: Leishmania parasites were isolated from the bone marrow aspirate of a patient with visceral leishmaniasis. Parasites were typed as Leishmania donovani by restriction fragment length polymorphism of internal transcribed spacer 1 region of Leishmania genome. Promastigotes were incubated in a fixed ratio combination of artemisinin (0-500 μM) and amphotericin B (0-100 nM) or miltefosine (0-100 μM) and cell viability was assessed. An isobologram was constructed to evaluate the additive/synergistic effect, wherein it was considered additive if the mean sum fractional inhibitory concentration (mean ΣFIC) at the IC50 level was <2, but ≥1 and synergism, if the mean ΣFIC was <1. Results: The isobologram showed an additive effect for three combinations of artemisinin-amphotericin B and artemisinin-miltefosine, the mean ΣFICs ranging from 1.02 to 1.44 and 1.08 to 1.33 along with a synergistic effect with one combination, the mean ΣFICs being 0.58 and 0.81 respectively. Conclusions: This study supports the combination use of artemisinin-amphotericin B and artemisinin-miltefosine, worthy of future pharmacological consideration.

Evaluation of leishmanicidal effect of Euphorbia erythadenia extract by in vitro leshmanicidal assay using promastigotes of Leishmania major

Objective:To evaluate leishmanicidal effects of Euphorbia erythadenia plant extract. Methods:Extraction was done using methanolic Soxhlet of dried and ground aerial parts of the plant. Then, five different extract concentrations, in addition of positive, negative and solvent controls were prepared and added to a 24-well plate containing 40 000 parasites/well. The extract concentrations were 1, 0.5, 0.25, 0.125 and 0.062 5 mg/mL. Amphotricin B (0.5 mg/mL) was used as positive control while negative control contained only culture medium. After 3 d incubation at 25 °C the amount of parasites in each well was determined on each day of experiment microscopially using Neubar chamber. Results:Soxhlet extract as well as amphotricin B killed all parasites at concentration of 1 mg/mL. The leshmanicidal activity of lower doses of extract was dose-dependent. The EC50 for Soxhlet extracts in dimethylsulfoxide was 0.30 mg/mL. The EC50 for Soxhlet extracts in methanol was 0.23 mg/mL. No obvious effects from the control solvent on the Leishmania major promastigotes were observed. Conclusions: The Soxhlet extract of Euphorbia erythadenia showed suitable leishmanicidal activity, especially in higher concentration fractions.

Atividade leishmanicida in vitro de Eugenia uniflora e Momordica charantia / Antileishmanial in vitro activity of Eugenia uniflora and Momordica charantia

A Leishmaniose Tegumentar Americana no Brasil é causada por uma variedade de espécies de Leishmania e uma grande diversidade destes parasitas pode ser encontrada na Região Amazônica. Revisões recentes na quimioterapia de leishmaniose enfatizam as deficiências dos agentes terapêuticos atualmente disponíveis e mostram a necessidade urgente de novos candidatos. Uma alternativa para substituir esses medicamentos são extratos naturais de Eugenia uniflora e Momordica charantia. Foram preparados extratos etanólicos das folhas de E. uniflora e M. charantia. Para os testes in vitro de Leishmania brasiliensis foram utilizadas formas promastigotas. O ensaio de citotoxicidade foi realizado com linhagens de fibroblastos. Nossos resultados indicam que E. uniflora foi eficaz contra a cepa de parasita testada, representando uma fonte alternativa de produtos naturais com atividade contra L. brasiliensis.

Cutaneous leishmaniasis is caused in Brazil by several species of the genus Leishmania and a wide variety of these protozoan parasites can be found in Brazil, mainly in the Amazon region. Recent reviews on the chemotherapy of leishmaniasis show the low effectiveness of the usual therapeutic agents, demonstrating the need for new drugs. An interesting possible alternative to the conventional drugs is offered by natural products extracted from Eugenia uniflora and Momordica charantia. Ethanol extracts were prepared from the leaves of Eugenia uniflora and Momordica charantia and assayed in vitro against Leishmania brasiliensis promastigotes and fibroblasts to assess their antileishmanial and cytotoxic activities, respectively. Our results indicate that E. uniflora was active against the parasitic forms of L. brasiliensis

In vitro efficacy of Coriandrum sativum, Lippia sidoides and Copaifera reticulata against Leishmania chagasi / Eficácia in vitro de Coriandrum sativum, Lippia sidoides e Copaifera reticulata sobre Leishmania chagasi

The increased incidence of visceral leishmaniasis (VL) in Brazil is due to a lack of effective disease control measures. In addition to that, no effective treatment exists for canine VL in response to synthetic drugs. Thus, the objective of this study was to evaluate the effect of the essential oils of Coriandrum sativum and Lippia sidoides, and oleoresin from Copaifera reticulata, on Leishmania chagasi promastigotes and amastigotes. We also examined the toxicity of these treatments on the murine monocyte cell line RAW 264.7. To determine the IC50 a MTT test (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) was performed on promastigotes, and an in situ ELISA assay was conducted on amastigotes. Here, we demonstrate that oleoresin from C. reticulata was effective against both promastigotes (IC50 of 7.88 µg.mL-1) and amastigotes (IC50 of 0.52 µg.mL-1), and neither of the two treatments differed significantly (p > 0.05) from pentamidine (IC50 of 2.149 µg.mL-1) and amphotericin B (IC50 of 9.754 µg.mL-1). Of the three plant oils tested, only oleoresin showed no toxicity toward monocyte, with 78.45% viability after treatment. Inhibition of promastigote and amastigote growth and the lack of cytotoxicity by C. reticulata demonstrate that oleoresin may be a viable option for analyzing the in vivo therapeutic effects of leishmanicidal plants.

O aumento na incidência da Leishmaníase Visceral (LV) no Brasil deve-se à ineficácia das medidas de controle da doença. Além disso, não há tratamento efetivo para LV canina com drogas sintéticas. Assim, o objetivo deste trabalho foi avaliar o efeito dos óleos essenciais de Coriandrum sativum e de Lippia sidoides e do óleo-resina de Copaiferareticulata sobre promastigotas e amastigotas de Leishmania chagasi e analisar o grau de toxicidade sobre células monocíticas murinas RAW 264.7. Para determinar a CI50 sobre promastigotas foi usado teste MTT (brometo de 3-[4,5-dimetil-tiazol-2-il]-2,5-difeniltetrazólio) e sobre amastigotas foi realizado imunoensaio in situ pela técnica de ELISA. Os resultados obtidos comprovaram que o óleo-resina de C. reticulata foi o mais eficaz contra as formas promastigotas (CI50 de 7,88 µg.mL-1) e amastigotas (CI50 de 0,52 µg.mL-1) e em nenhum dos dois testes diferiu do controle pentamidina que obteve CI50 de 2,149 µg.mL-1, no teste sobre promastigotas, e anfotericina B que obteve CI50 de 9,754 µg.mL-1, nos testes com amastigotas (p > 0.05). Quanto à citotoxicidade apenas o óleo-resina não apresentou toxicidade com 78,45% de monócitos viáveis. Os resultados obtidos sobre promastigotas e amastigotas e a ausência de citotoxicidade do óleo-resina de C. reticulata evidenciam que este óleo-resina pode ser viável para a análise de seus efeitos terapêuticos em testes in vivo.

Effects of seco-steroids purified from Physalis angulata L., Solanaceae, on the viability of Leishmania sp / Efeitos de seco-esteróides purificados de Physalis angulata L., Solanaceae na viabilidade de Leishmania sp

Physalis angulata L., Solanaceae, is an annual herb commonly used in popular medicine in many tropical and subtropical countries. P. angulata extracts contain a variety of substances, but little is known about their pharmacological activities. In this work we investigated the in vitro antileishmanial activity of seco-steroids (physalins) purified from P. angulata. Addition of physalins B, F, and G caused a concentration-dependent inhibition in the growth of L. amazonensis promastigotes, being the IC50 values were 6.8, 1.4, and 9.2 μM, respectively. Physalin D was less active and had an IC50 value of 30.5 μM. Physalins were also active in cultures of other Leishmania species (L. major, L. braziliensis, and L. chagasi). Our results demonstrate the potent antileishmanial activity of physalins in cultures of Leishmania species of the New and Old Worlds and suggest the therapeutic potential of these seco-steroids in leishmaniasis.

Physalis angulata L., Solanaceae, é uma erva anual utilizada na medicina popular em muitos países tropicais e subtropicais. Apesar dos extratos da P. angulata apresentarem uma grande variedade de substâncias, pouco é conhecido sobre a sua atividade farmacológica. Neste trabalho foi investigado a atividade antileishmania in vitro de seco-esteroides (fisalinas) purificados da P. angulata. O tratamento com as fisalinas B, F e G causou uma inibição concentração-dependente do crescimento de promastigotas de Leishmania amazonensis em cultura axênica, com valores de IC50 de 6,8, 1,4, e 9,2 μM respectivamente. A fisalina D foi menos ativa, com valores de IC50 de 30,5 μM. Foi também observada uma atividade leishmanicida em culturas de outras espécies de Leishmania (L. major, L. braziliensis e L. chagasi). Nossos resultados demonstram que as fisalinas inibem o crescimento dos promastigotas com o tratamento de espécies de Leishmania do Velho e do Novo Mundos e sugerem o potencial terapêutico destas moléculas na leishmaniose.

Experimental chemotherapy with Allium sativum (Liliaceae) methanolic extract in rodents infected with Leishmania major and Leishmania donovani.

Background & objectives: Several plant products have been tested and found to possess antileishmanial activity. The present study was undertaken to establish whether methanolic extract of Allium sativum Linn has antileishmanial activity in comparison to standard drugs. Methods: Methanolic extract of A. sativum bulbs was screened for in vitro and in vivo antileishmanial activity against Leishmania major strain (NLB 145) and L. donovani strain (NLB 065). Pentostam® and Amphotericin B® were used as standard drugs. BALB/c mice and golden hamsters (Mesocricetus auratus) were used in in vivo studies on L. major and L. donovani respectively. Results: The extract exhibited very low cytotoxicity (IC50 >450 μg/ml) against Vero cells. The extract had significantly better (p <0.001) leishmanicidal activity against both species (IC50 34.22 μg/ml to L. major, 37.41 μg/ml to L. donovani) than Pentostam. However, the activity was significantly lower (p <0.001) than that of Amphotericin B against both the species. At a concentration of 250 μg/ml, the extract induced the production of 60 μM of nitric oxide, a ten-fold up-regulation in activated macrophages. The multiplication indices for L. major amastigotes treated in 100 μg/ml were significantly different (p <0.05). Treatment with the extract, daily for 28 days led to a significant reduction (p <0.05) in footpad swelling in BALB/c mice; similar activity noticed in the treatment with standard drugs. The Leishman-Donovan Units (LDU) for the extract treated animals were significantly higher (p <0.05) than those of standard drugs, but lower compared to the negative control. Interpretation & conclusion: Since the mechanism of action for the methanolic extract is apparently immunomodulatory, garlic compounds could be purified and tried as complementary medicine in the management of leishmaniases.

Subcutaneous immunization against Leishmania major - infection in mice: efficacy of formalin-killed promastigotes combined with adjuvants / Imunização subcutânea na infecção do camundongo pela Leishmania major: eficácia dos promastigotos mortos pela formalina combinada com adjuvantes

Formalin-killed promastigotes (FKP) of Leishmania major, in combination with Montanide ISA 720 (MISA), BCG or alum were used in vaccination of an inbred murine model against cutaneous leishmaniasis (CL). Significant and specific increases in anti-FKP IgG responses were detected for both alum-FKP and BCG-FKP compared to MISA-FKP (p < 0.001). Significant increases in splenic lymphocyte recall proliferation was obtained in the MISA-FKP vaccinated mice compared to alum-FKP or BCG-FKP vaccinated groups (p < 0.01). The highest interferon-ã responses were observed in the BCG-FKP group followed by the MISA-FKP while the alum-FKP gave the least responses. Significantly reduced lesion sizes were obtained in the MISA-FKP group compared to the BCG/alum adjuvants-FKP vaccinated groups. Although the BCG-FKP group showed the highest IFN-ã responses, it failed to control cutaneous lesions. Significant reductions in parasite numbers were observed in the MISA-FKP and BCG-FKP vaccinated groups (p < 0.001). There was a good correlation between parasite burden and IFN-ã level indicating IFN-ã response as a sensitive parameter of the immune status. In conclusion, MISA-FKP is the most efficacious vaccine formulation against murine cutaneous leishmaniasis.

Promastigotos mortos pela formalina (FKP) de Leishmania major combinados com Montanide ISA 720 (MISA), BCG ou alumen foram usados na vacinação de modelo murino cutâneo de leishmaniose (CL). Aumento significante e específico de resposta IgG anti FKP foram detectados tanto no FKP com alumen como naquele com BCG comparados ao MISA-FKP (p < 0,001). Aumento significante da proliferação esplênica de linfócitos de memória foi obtida nos camundongos vacinados com MISA-FKP quando comparados aos grupos vacinados com alumen-FKP ou BCG-FKP (p < 0,01). As maiores respostas por interferon-gama foram observadas no grupo BCG-FKP seguido pelo MISA-FKP enquanto que o alumen-FKP deu a menor resposta. No grupo MISA-FKP foram obtidas reduções significantes do tamanho das lesões quando comparado aos grupos vacinados com BCG/adjuvante de alumen-FKP. Embora o grupo BCG-FKP tenha mostrado a maior resposta por interferon-gama, não houve controle das lesões cutâneas. Redução significante no número de parasitas foi observada tanto no grupo vacinado com MISA-FKP como no BCG-FKP (p < 0,001). Houve boa correlação entre a carga parasitária e o nível de interferon-gama indicando que a resposta do interferon-gama é parâmetro sensível do estado imunológico. Em conclusão, MISA-FKP é a forma mais eficaz de vacina contra a leishmaniose cutânea murina.

Antileishmanial phenylpropanoids from Alpinia galanga (Linn.) Willd.

Hexane, chloroform and ethyl acetate extracts (100 µg/ml) of Alpinia galanga rhizomes exhibited significant activity in vitro against promastigotes of L. donovani. Twelve compounds namely, methyleugenol (1), p-coumaryl diacetate (2), 1'-acetoxychavicol acetate (3), 1'-acetoxyeugenol acetate (4), trans-p-acetoxycinnamyl alcohol (5), trans-3,4-dimethoxycinnamyl alcohol (6), p-hydroxybenzaldehyde (7), p-hydroxycinnamaldehyde (8), trans-p-coumaryl alcohol (9), galangin (10), trans-p-coumaric acid (11) and galanganol B (12) were isolated from these extracts. Of these, compounds 2, 3, 4 and 5 were found most active in vitro against promastigotes of L. donovani with IC50 values of 39.3, 32.9, 18.9 and 79.9 µM respectively. This is the first report of antileishmanial activity of the extracts and isolated constituents of A. galanga.

Estudio de la infección de Leishmanias del complejo Viannia mediante citometría de flujo y coloración de Giemsa empleando líneas de macrófagos humanos y murinos (U-937 y J-774) / Study of Leishmania Viannia infection by means of flow cytometry and Giemsa stain using human and murine macrophage lines (U-937 and J-774)

Ante las dificultades frente al tratamiento de la leishmaniasis, es importante buscar alternativas terapéuticas que deben ser analizadas empleando modelos in vitro e in vivo adecuadamente estandarizados. Con este propósito, se implementó un modelo de infección in vitro de Leishmania conmacrófagos U-937 y J-774, para evaluar la internalización de promastigotes a distintos puntos tiempo (2 a 6 horas) y por dos técnicas: coloración de Giemsa (CG) y citometría de flujo (CF). En el análisis por CF, se evaluó la invasión teniendo en cuenta la emisión de fluorescencia de los parásitos transfectados con la proteína verde de fluorescencia (GFP) y el aumento de la densidad citoplasmática de los macrófagos debida a los parásitos internalizados, lo cual fue verificado con el recuento microscópico realizado con CG; se encontró que a una proporción 1:35 (células:parásitos) se pueden establecer cambios densitométricos asociados con la infección empleando cepas de parásitos no transfectadas. También se describe que las J774 internalizan más eficientemente promastigotes de Leishmania que las células U937 (P valor: 0,0006), y se observa a su vez para la línea murina un aumento del número de parásitos por célula, respecto a los macrófagos humanos empleados en este ensayo (P valor 0,0038). Este estudio nos permite concluir: (i) que los cambios en la densidad citoplasmática evidenciados por CF son suficientes para establecer el porcentaje de infección parasitaria, aun para aquellos parásitos no transfectados; (ii) que la CG es menos costosa que el uso de la CF para evaluar infección parasitaria, aunque por su carácter semicuantitativo, la variabilidad intra- e inter-observadores la hace menos precisa; (iii) que los resultados cuantitativos obtenidos por la CF se correlacionan con los observados en la CG, y permiten sugerir que estas dos técnicas resultan complementarias; y (iv) que el porcentaje de infección y el número de parásitos internalizados para la J-774 son mayores que lo encontrado para la U-937, lo cual puede deberse a que un mayor número de receptores de complemento sobre la línea murina favorece la internalización de patógenos intracelulares, proceso menos favorecido en la línea humana por los niveles reducidos de este tipo de receptores en su membrana celular.

The treatment for Leishmaniasis has presented some difficulties related with adverse effects and resistance. For these reasons it is important to search therapeutic alternatives which must be analyzed using adequately standardized in vitro and in vivo models. With this purpose, we implemented an in vitro model for leishmania infection using U-937 and J-774macrophages, and evaluating promastigote internalization at consecutive time spans (from 2 to 6 hours). The first approximation assayed involves the flow cytometric (CF) analysis for invasion quantification by measuring the fluorescence emitted by parasites previously transfected with green fluorescence protein (GFP). In the alternative strategy, parasitized cells were subjected to Giemsa stain and CF was applied to measure the increase of macrophages cytoplasm density owed to internalized parasites. Giemsa stain also allowed us to estimate the number of parasites within each cell. We report that the presence of 35 parasites per macrophage produces an increase in cytoplasmic density enough to be detected by CF so that infection can be clearly reported. We also found that J-774 macrophages internalize Leishmania promastigotes more efficiently than U-937 cells (P value: 0.0006). Cells of the murine line were infected by a higher number of parasites than the human counterparts used in this study (P value 0.0038). From the resultas, we conclude: (i) the change in macrophage cytoplasm density demonstrated by CF after Giemsa stain are sufficient to estimate the percentage of infection. (ii) Giemsa stain provides a less expensive strategy to evaluate Leishmania infection than the fluorescence based option, although the intra and inter observer variability (semi-quantitative procedure) makes it less precise; (iii) quantitative results obtained by both techniques correlate to each other, suggesting that these two tools can be considered complementary; and (iv) both the percentage of infection and the number of internalized parasites are higher for J-774 than for U-937 macrophages. This probably suggests the presence of more receptor molecules (binding targets) for Leishmania ligands on the murine cell membrane determining a more efficient internalization rate than in human macrophages.

Efecto de derivados de la tiadiazina sobre la capacidad infectiva de promastigotes de Leishmania amazonensis / Effects of thiadiazine derivatives on the infective capacity of Leishamia amazonensis promastigotes

Se evaluó la capacidad infectiva de promastigotes de Leishmania amazonensis al ser tratados con una serie de 10 derivados de la tiadiazina. Los parásitos fueron incubados durante 24 h con 1 o 0,1 mg/mL de cada compuesto y posteriormente, se infectaron macrófagos peritoneales de ratones BALB/c en cultivos. Todos los compuestos causaron una reducción de la capacidad infectiva de los parásitos mayor que 50 %. El producto T1O fue el que causó un mayor efecto, disminuyendo la infección en 92,8 % de infección.

The infective capacity of Leishmania amazonensis promastigotes was evaluated after they were treated with a series of 10 thiadiazine derivatives. The parasites were incubated for 24 hours with 1 or 0,1 mg/ml of each compound and then, peritoneal macrophages from BALB/c mice were infected in cultures. All the compounds managed to reduce the infective capacity of parasites by more than 50%. T10 product exhibited the highest effect since it reduced infection by 92,8%.

Identification of novel Leishmania major antigens that elicit IgG2a response in resistant and susceptible mice

Experimental murine models with high, intermediate and low levels of genetically based susceptibility to Leishmania major infection reproduce almost entire spectrum of clinical manifestations of the human disease. There are increasing non-comparative studies on immune responses against isolated antigens of L. major in different murine strains. The aim of the present study was to find out whether there is an antigen that can induce protective immune response in resistant and susceptible murine strains. To do that, crude antigenic extract of procyclic and metacyclic promastigotes of L. major was prepared and subjected to SDS-PAGE electrophoresis. Western-blotting was used to search for antigen(s) capable of raising high antibody level of IgG2a versus IgG1 in the sera of both infected resistant and susceptible strains. Two novel antigens from metacyclic promastigotes of L. major (140 and 152 kDa) were potentially able to induce specific dominant IgG2a responses in BALB/c and C57BL/6 mice. The 2 antigens also reacted with IgG antibody of cutaneous leishmaniasis patients. We confirm that 140 and 152 kDa proteins of L. major promastigotes are inducing IgG production in mice and humans.

Behavior of Leishmania major metacyclic promastigotes during the course of infection and immune response development in resistant versus susceptible hosts

Little is known on the epitopes derived from metacyclic promastigotes of Leishmania that are important on the regulation or destruction of the parasite, as targets of immune attack in the vertebrate host. In this study we investigated an alternative method to obtain metacyclic promasigotes of Leishmania major, as evaluated by the course of infection and delayed-type hipersensitivity (DTH) in resistant versus susceptible inbred mice. Non-infective (procyclic) promastigotes of L. major recently transformed from tissue amastigotes were attached to a negatively charged glass-wool column, whereas metacyclic promastigotes were not bound to columns and could be easily recovered. Optimal chromatography conditions were validated through statistical analyses. Parasite average yield from glass wool columns and promastigote viability were estimated by light microscopy. Metacyclic promastigotes yielded 43.5% to 57.5%. Different patterns of cutaneous lesions were obtained in BALB/c (susceptible) and C57BL/6 (resistant) mice, the former with highly infective lesions induced by metacyclic promastigotes. DTH responses proved to be higher in groups of C57BL/6 mice which were infected with metacyclic promastigotes. These results indicate that the new method could be integrated with the investigation of metacyclogenesis of Leishmania in vivo.

Pouco se conhece sobre os epítopos derivados de promastigotas metacíclicos de Leishmania que são importantes para a regulação ou destruição do parasita, como alvos de ação imunológica no hospedeiro vertebrado. Neste estudo, nós investigamos um método alternativo para obter promastigotas metacíclicos de Leishmania major, pela avaliação do curso da infecção e reação de hipersensibilidade do tipo retardado (HTR) em hospedeiros resistentes e susceptíveis. Promastigotas não-infectantes (procíclicos) de L. major, recentemente isolados de amastigotas, foram selecionados pela adesão a colunas de lã de vidro negativamente carregadas, enquanto que promastigotas metacíclicos não se aderem à coluna e podem ser recuperados com facilidade. Condições ótimas de cromatografia foram validadas por análise estatística. O rendimento médio de parasitas obtidos após separação em colunas de lã de vidro e a viabilidade dos promastigotas foram estimados por microscopia óptica. Os promastigotas metacíclicos tiveram um rendimento médio de 43,5% a 57,5%. Camundongos BALB/c (susceptíveis) e camundongos C57BL/6 (resistentes) apresentaram padrões distintos de lesões cutâneas, os primeiros com lesões mais agressivas, induzidas por promastigotas metacíclicos. As respostas à reação de HTR foram maiores nos grupos de camundongos C57BL/6, submetidos à infecção com promastigotas metacíclicos. Estes resultados indicam que o novo método poderia ser integrado aos protocolos existentes para estudar a metaciclogênese de parasitas do gênero Leishmania in vivo.

Behavior of Leishmania major metacyclic promastigotes during the course of infection and immune response development in resistant versus susceptible hosts

Little is known on the epitopes derived from metacyclic promastigotes of Leishmania that are important on the regulation or destruction of the parasite, as targets of immune attack in the vertebrate host. In this study we investigated an alternative method to obtain metacyclic promasigotes of Leishmania major, as evaluated by the course of infection and delayed-type hipersensitivity (DTH) in resistant versus susceptible inbred mice. Non-infective (procyclic) promastigotes of L. major recently transformed from tissue amastigotes were attached to a negatively charged glass-wool column, whereas metacyclic promastigotes were not bound to columns and could be easily recovered. Optimal chromatography conditions were validated through statistical analyses. Parasite average yield from glass wool columns and promastigote viability were estimated by light microscopy. Metacyclic promastigotes yielded 43.5% to 57.5%. Different patterns of cutaneous lesions were obtained in BALB/c (susceptible) and C57BL/6 (resistant) mice, the former with highly infective lesions induced by metacyclic promastigotes. DTH responses proved to be higher in groups of C57BL/6 mice which were infected with metacyclic promastigotes. These results indicate that the new method could be integrated with the investigation of metacyclogenesis of Leishmania in vivo.

Pouco se conhece sobre os epítopos derivados de promastigotas metacíclicos de Leishmania que são importantes para a regulação ou destruição do parasita, como alvos de ação imunológica no hospedeiro vertebrado. Neste estudo, nós investigamos um método alternativo para obter promastigotas metacíclicos de Leishmania major, pela avaliação do curso da infecção e reação de hipersensibilidade do tipo retardado (HTR) em hospedeiros resistentes e susceptíveis. Promastigotas não-infectantes (procíclicos) de L. major, recentemente isolados de amastigotas, foram selecionados pela adesão a colunas de lã de vidro negativamente carregadas, enquanto que promastigotas metacíclicos não se aderem à coluna e podem ser recuperados com facilidade. Condições ótimas de cromatografia foram validadas por análise estatística. O rendimento médio de parasitas obtidos após separação em colunas de lã de vidro e a viabilidade dos promastigotas foram estimados por microscopia óptica. Os promastigotas metacíclicos tiveram um rendimento médio de 43,5% a 57,5%. Camundongos BALB/c (susceptíveis) e camundongos C57BL/6 (resistentes) apresentaram padrões distintos de lesões cutâneas, os primeiros com lesões mais agressivas, induzidas por promastigotas metacíclicos. As respostas à reação de HTR foram maiores nos grupos de camundongos C57BL/6, submetidos à infecção com promastigotas metacíclicos. Estes resultados indicam que o novo método poderia ser integrado aos protocolos existentes para estudar a metaciclogênese de parasitas do gênero Leishmania in vivo.

Expression of antigens in virulent and avirulent Indian strains of Leishmania donovani.

Indo-Gen mediated surface labelling with 125I demonstrated differences in surface oriented antigens between virulent and virulent promastigote of Leishniania donovani, In case of virulent strains, surface polypeptides with molecular masses of 63, 53, 42 and 38 kDa were found to be labelled with 125I whereas in the case of aviralent stains 68, 55, 50, 46, 42 and 33 Da, components were iodinated. Further studies by immunoblot assay using different subcellular fractions of virulent and avirulent parasites demonstrated that antibody raised against gp63 cross-reacted with the 63 and 60 kDa antigen of the virulent and avirulent Leishmania donovani strains of Indian origin respectively. It indicates that these two polypeptides are antigenically similar. When virulent and avirulent cells were grown in the presence of varying concentration of tunicarnycin and immunoblot with anti gp63, it was observed that with increasing concentration of tunicamycin the 63 kDa polypeptide of the virulent cells shifted to approximately 58-57 kDa and the 60 kDa polypoptide of the aviruleni cells shifted to 57 kDa. This suggests that glycosylation may play an important role in antigenic variation between virulent and avirulent parasites.