Microgramma vacciniifolia Frond Lectin: In Vitro Anti-leishmanial Activity and Immunomodulatory Effects Against Internalized Amastigote Forms of Leishmania amazonensis.

PURPOSE: The treatment of leishmaniasis, an anthropozoonosis caused by Leishmania protozoa, is limited by factors, such as adverse effects, toxicity, and excessive cost, which has highlighted the importance of novel drugs. In this context, natural products have been considered as sources of antileishmanial agents. This study investigated the leishmanicidal activity of Microgramma vacciniifolia frond lectin (MvFL) on promastigotes and amastigotes of Leishmania amazonensis. METHODS: The effects of MvFL on promastigote proliferation and macrophage infection by amastigotes were evaluated and mean inhibitory concentrations (IC50) were calculated. As a safety assessment, the hemolytic capacity of MvFL (6.25-200 µg/mL) against mouse and human erythrocytes was determined. Additionally, the ability of MvFL (6.25-100 µg/mL) to modulate lysosomal and phagocytic activities and the nitric oxide (NO) production by murine peritoneal macrophages was also investigated. RESULTS: After 24 h, MvFL inhibited the proliferation of L. amazonensis promastigotes, with an IC50 of 88 µg/mL; however, hemolytic activity was not observed. MvFL also reduced macrophage infection by amastigotes with an IC50 of 52 µg/mL. Furthermore, treatment with MvFL reduced the number of amastigotes internalized by infected murine peritoneal macrophages by up to 68.9% within 48 h. At a concentration of 25 µg/mL, MvFL stimulated lysosomal activity of macrophages within 72 h, but did not alter phagocytic activity or induce NO production at any of the tested concentrations. CONCLUSION: MvFL exerts antileishmanial activity and further studies are needed to assess its therapeutic potential in in vivo experimental models of leishmaniasis.

Methods of macrophages activation and their modulation for the prospection of new antileishmania drugs: a review

Leishmaniasis are a group of parasitic zoonoses provoked by protozoa from Leishmania genus and belonging to the group of neglected tropical diseases. The search and development for new drugs is necessary not only to investigate the activity against only the parasite, but also to investigate the possible synergistic effect of new drugs with the immune response of the host. In the present review, macrophages are pointed out as potential targets of the investigation of new antileishmanial drugs, and some methodologies in order to assess their activation as response to Leishmania-infected cells are presented. Macrophages are an important role in the cellular immune response, since they are cells from mononuclear phagocytic system, the first line of defense of the host, against parasites from Leishmania genus. Phagocytic capacity, lysosomal activity, increase of nitric oxide and intracellular calcium levels are parameters regarding assessment of macrophages activation which allow them to be more hostile in order to solve the infection and lead the patient to cure. In this context, we bring 19 substances already investigated and that activate macrophages, what makes them promising in the antileishmanial treatment. Therefore, assessment of macrophages activation, are important tools for discovery of immunomodulatory compounds which have potential to act in synergism with host immune response. Such compounds might be promising as monotherapy in the treatment of leishmaniasis, as well as being used as adjuvants in vaccines and/or in combination with conventional drugs.

Amphotericin B-Loaded Emulgel: Effect of Chemical Enhancers on the Release Profile and Antileishmanial Activity In Vitro.

Cutaneous leishmaniasis is a neglected parasitic disease. Treatment is preferably performed with pentavalent antimony associated or not with amphotericin B (AmB). This study aimed to develop an emulgel with different chemical enhancers of cutaneous release. Initially, AmB emulsions were obtained with the chemical promoters, oleic acid and geraniol and without promoter, then for the evaluation of the formulations, a preliminary stability study was carried out where the formulations were submitted to centrifugation, before and after the freeze-thaw cycle and analyzed appearance, color, pH, spreadability, viscosity, conductivity, droplet size, assay, in vitro release study, in vitro antileishmania activity in Leishmania major promastigotes, and macrophage toxicity in the MTT test. The emulsions were yellowish, with no signs of instability after the centrifugation test. The pH range corresponded to that of the skin, which is 4.6 to 5.8, before and after the freeze-thaw cycle, the formulations had good spreadability and did not present significant viscosity differences before and after the freeze-thaw cycle, presenting a non-Newtonian characteristic. AmB content was within the kinetic model of zero order release, the formulation of 3% AmB and 5% oleic acid (formulation 1) was chosen to proceed with the antileishmania activity test and showed potential activity against the in vitro parasite with significant reduction of cytotoxicity on murine macrophages, indicating that the formulation is promising for the treatment of cutaneous leishmaniasis.

Platonia insignis Mart., a Brazilian Amazonian Plant: The Stem Barks Extract and Its Main Constituent Lupeol Exert Antileishmanial Effects Involving Macrophages Activation.

Platonia insignis Mart., popularly known as "bacurizeiro," is used in traditional medical practices based on its diverse biological properties. This study was aimed at evaluating the antileishmanial effects of the ethanol extract (EtOH-Ext), hexane fraction (Hex-F), and its main isolated Lupeol obtained from stem barks of P. insignis against Leishmania (Leishmania) amazonensis, as well as their cytotoxicity and possible mechanisms of action. The EtOH-Ext, Hex-F, and Lupeol inhibited the growth of L. amazonensis promastigote forms at IC50 of 174.24, 45.23, and 39.06 µg/mL, respectively, as well as L. amazonensis axenic amastigote forms at IC50 of 40.58, 35.87, and 44.10 µg/mL, respectively. The mean cytotoxic concentrations for macrophages (CC50) were higher than those for amastigotes (341.95, 71.65, and 144.0 µg/mL, resp.), indicating a selective cytotoxicity towards the parasite rather than the macrophages. Interestingly, all treatments promoted antileishmanial effect against macrophage-internalized amastigotes at concentrations lower than CC50. Furthermore, increases of lysosomal volume of macrophages treated with EtOH-Ext, Hex-F, and Lupeol were observed. On the other hand, only Lupeol stimulated increase of phagocytic capability of macrophages, suggesting this compound might be characterized as the biomarker for the antileishmanial effect of P. insignis stem bark, as well as the involvement of immunomodulatory mechanisms in this effect.

In Vitro Effects of the Neolignan 2,3-Dihydrobenzofuran Against Leishmania Amazonensis.

Leishmaniasis is an infectious disease complex caused by protozoa from the Leishmania genus, which presents a broad spectrum of clinical manifestations: cutaneous, mucocutaneous and visceral forms. The current treatments are unsatisfactory considering that few drugs are available and present some level of toxicity. Many lignans and neolignans have been used for the development of new antileishmania drugs. The capability in vitro of the neolignan 2,3-dihydrobenzofuran (2,3-DBF), a commonly found constituent of propolis and other plants, to inhibit the growth of promastigote and macrophage-internalized amastigote forms of Leishmania amazonensis was investigated. The cytotoxicity of this compound was assessed by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) test in BALB/c murine macrophages and human erythrocyte lysis assay. The 2,3-DBF was active against promastigote (IC50 =1.042 µM) and amastigote (IC50 =1.43 µM) forms, indicating a potent antileishmanial effect. There was no evidence of cytotoxicity to macrophages or erythrocytes at concentrations ranging from 13 to 0.5 µM, after 48 hr of exposure. The antileishmanial activity is probably mediated by the activation of macrophages, because treatment with 2,3-DBF increases both phagocytic and lysosomal activities, as well as the nitrite (NO2- ) levels. These results suggest that 2,3-DBF may be a potential candidate for the development of a new promising antileishmanial drug. Further studies are needed to determine its potential in vivo effect as well as additional mechanisms underlying the antileishmanial and immunomodulatory activities.

Occurrence of antibodies against Leptospira spp in dogs from Teresina, Piauí, Brazil / Ocorrência de anticorpos contra Leptospira spp em cães de Teresina, Piauí, Brasil

Leptospirosis is a systemic disease caused by the species of bacteria Leptospira spp., which affects human beings, domestic and wild animals. The present study searched the presence of antibodies against Leptospira spp. in the canine population of the city Teresina, Piauí, and the most common serovars. Blood samples from 425 stray dogs were collected in the local zoonosis center in Teresina from July 2010 to January 2012 and submitted to the Microscopic Seroagglutination Test (MAT). This study found an average infection rate of 17.41% (IC 95%; 13,8 ­ 21,0) by 11 different serovars; the four most frequent were Canicola (18.9%), Autumnalis (16.2%), Icterohaemorrhagiae (12.1%), and Butembo (12.1%). The questions raised in this study indicated the occurrence of Leptospira spp infection in dogs of Terezina- Piaui, Brazil.(AU)

A leptospirose é uma doença sistêmica causada por bactéria Leptospira spp. que afeta seres humanos, animais domésticos e selvagens. O presente trabalho investigou a presença de anticorpos anti-Leptospira spp. na população canina da cidade de Teresina-Piauí, e os respectivos sorovares predominantes. Amostras de sangue de 425 cães foram coletadas no Centro de Controle de Zoonoses de Teresina, no período de julho de 2010 a janeiro de 2012, e submetidas à prova de Soroaglutinação Microscópica (SAM). Este estudo encontrou uma taxa de infecção média com 17,41% (IC 95%; 13,8 ­ 21,0) e 11 sorovares reagentes, sendo os prevalentes Canicola (18,9%), Autumnalis (16,2%), Icterohaemorrhagiae (12,1%) e Butembo (12,1%). As questões levantadas neste estudo indicam a ocorrência de infecção por Leptospira spp em cães da cidade de Teresina-Piauí, Brasil.(AU)