Antileishmanial drugs activate inflammatory signaling pathways via toll-like receptors (docking approach) from Leishmania amazonensis-infected macrophages.

The activation of proinflammatory cellular processes and signals such as those linked to NF-kB in macrophages are involved in the control of infection by Leishmania ssp. However, little is known about the influence of the drugs used in the treatment on the host cellular inflammatory signaling pathways. This study aimed to evaluate the effects of different drugs used in the treatment of leishmaniasis on inflammatory profile related to Toll-like receptors (TLRs) from L. amazonensis-infected macrophages. J774 macrophage-like cells were infected with the promastigote forms (5:1) and 24 hs incubated with Amphotericin B (AmB), Glucantime® (GLU) or Pentamidine (Pent). The following inflammatory pathways were evaluated: NF-κB p65, NF-κB p65 phosphorylated (Ser536), stress-activated protein kinase/c-Jun NH(2)-terminal kinase (SAPK/JNK) phosphorylated (Thr183/Tyr185), p38 mitogen activated protein kinase (MAPK p38) phosphorylated (Thr180/Tyr182), signal transducer and activator of transcription-3 (Stat3) phosphorylated (Tyr705) and inhibitor kappa B-α (IκB-α) phosphorylated (Ser32). In silico tests were performed to evaluate the molecular affinity between TLRs and antileishmanial drugs. Molecular docking showed that affinities varied significantly among the binders evaluated. The lowest affinity (-8.6 Kcal/Mol) was calculated for AmB in complex with TLR4. Pent showed higher values for TLR1, TLR2 and TLR3, while for TLR4 the affinity value was lower (5.5 Kcal/Mol). The values obtained for GLU were the highest for the set of binders tested. From the infected macrophages, treatments inhibited NF-kB p65 for GLU (65.44%), for Pent (46.43%) and for AmB (54.07%) compared to untreated infected macrophages. The activation of the signaling pathway of NF-kB, SAPK/JNK and IκB-α caused by AmB and Pent may potentiate the microbicidal mechanisms of the infected macrophages.

Drug-containing hydrophobic dressings as a topical experimental therapy for cutaneous leishmaniasis.

Cutaneous leishmaniasis (CL), a clinical condition caused mainly by Leishmania amazonensis in Brazil, is characterized by topical, painless ulcers. The current treatment, based on intravenous administration of pentavalent antimonials, presents low adherence by patients and may cause serious adverse effects, leading to the need for searching new therapeutic options. Thus, this study aimed at evaluating a topical administration of "intelligent dressings" as an alternative treatment for CL. BALB/c mice were infected with L. amazonensis promastigotes. Afterward, lesions were treated with hydrophobic dressings incorporated with clinically used drugs. After lesion development, the following analyses were carried out: measurement of lesion diameters, biochemical analyses of serum, evaluation of the recovery of amastigote forms and histological analyses. No significant clinical changes in serum parameters were observed. The group that was treated with dressings impregnated with Glucantime® displayed the lowest number of amastigotes recovered from tissues (parasite load). Conventional treatment with Glucantime® (i.p.) was also able to reduce parasite load. After 6 weeks from the measurement of the lesions mice treated with dressings impregnated with Pentamidine displayed the smallest values. Representative histological aspects of the lesions showed the absence or few amastigotes inside the macrophages when mice were treated with dressings impregnated with Glucantime® and Pentamidine, respectively. The findings presented here indicate that the topical treatments may constitute an alternative treatment option for CL.

Screening of the in vitro antileishmanial activities of compounds and secondary metabolites isolated from Maytenus guianensis Klotzsch ex Reissek (Celastraceae) chichuá Amazon.

INTRODUCTION: Maytenus guianensis is a member of the Celastraceae family that is used in traditional medicine, particularly for its anti-parasitic and anti-cancer effects. To explore the ethnopharmacological potential of this plant, the present study was designed to screen the in vitro antileishmanial activities of extracts and compounds isolated from M. guianensis. METHODS: Maytenus guianensis stems and leaves were extracted in acetone, followed by the preparation of eluates and isolation of secondary metabolites using chromatography on a glass column with silica gel as the fixed phase. The chemical components were identified using spectroscopic methods, including one- and two-dimensional nuclear magnetic resonance of hydrogen-1 and carbon-13, mass spectroscopy, and infrared spectroscopy. The anti-Leishmania amazonensis activities of these eluates and compounds were evaluated by direct promastigote counting and viability assays. RESULTS: It was found that the hexane bark eluate produced the strongest anti-L. amazonensis effect, with 90-100% inhibition of the promastigote form. The isolated metabolite that produced the best result was tingenone B, followed by a compound formed by the union of tingenone and tingenone B (80-90% inhibition). CONCLUSIONS: Maytenus guianensis shows anti-parasite activity that warrants further investigation to determine the mechanisms underlying this antileishmanial effect and to evaluate the pharmacological potential of these eluates and isolated secondary metabolites, while minimizing any adverse effects.

Screening of the in vitro antileishmanial activities of compounds and secondary metabolites isolated from Maytenus guianensis Klotzsch ex Reissek (Celastraceae) chichuá Amazon

Abstract INTRODUCTION Maytenus guianensis is a member of the Celastraceae family that is used in traditional medicine, particularly for its anti-parasitic and anti-cancer effects. To explore the ethnopharmacological potential of this plant, the present study was designed to screen the in vitro antileishmanial activities of extracts and compounds isolated from M. guianensis. METHODS Maytenus guianensis stems and leaves were extracted in acetone, followed by the preparation of eluates and isolation of secondary metabolites using chromatography on a glass column with silica gel as the fixed phase. The chemical components were identified using spectroscopic methods, including one- and two-dimensional nuclear magnetic resonance of hydrogen-1 and carbon-13, mass spectroscopy, and infrared spectroscopy. The anti-Leishmania amazonensis activities of these eluates and compounds were evaluated by direct promastigote counting and viability assays. RESULTS It was found that the hexane bark eluate produced the strongest anti-L. amazonensis effect, with 90-100% inhibition of the promastigote form. The isolated metabolite that produced the best result was tingenone B, followed by a compound formed by the union of tingenone and tingenone B (80-90% inhibition). CONCLUSIONS Maytenus guianensis shows anti-parasite activity that warrants further investigation to determine the mechanisms underlying this antileishmanial effect and to evaluate the pharmacological potential of these eluates and isolated secondary metabolites, while minimizing any adverse effects.

Plantas da Amazônia brasileira com potencial leishmanicida in vitro / Plants of the Brazilian Amazon with potential in vitro antileishmania activity

A preocupação em buscar novos fármacos para o tratamento da leishmaniose é cada vez maior em virtude da toxicidade dos existentes e do aumento da resistência do parasito, o que representa uma ameaça ao controle da doença. O presente estudo apresenta uma revisão bibliográfica sobre as plantas da Amazônia brasileira com potencial atividade leishmanicida in vitro. Constatouse uma grande diversidade de espécies vegetais da Amazônia brasileira com potencial para a investigação de novos fitoterápicos e metabólitos secundários com ação leishmanicida, além do tratamento de outras parasitoses negligenciadas. A presente revisão demonstrou que as espécies dos gêneros Casearia, Croton e Physalis são fortes candidatas para busca de novos fármacos, visto que apresentaram um IC50 menor que 1µg/mL em testes in vitro contra as formas promastigotas ou amastigotas de Leishmania spp. Ressalta-se a importância de estudos futuros sobre espécies que apresentem metabólitos terpenoides ou esteroides em virtude do potencial leishmanicida que têm demonstrado.

The pentavalent antimonial therapy against experimental Leishmania amazonensis infection is more effective under the inhibition of the NF-κB pathway.

During Leishmania infection, host immune response is important to prevent the growth/survival of intracellular amastigotes. In this study, we evaluated in vitro and in vivo whether or not during Leishmania amazonensis infection, pentavalent antimonial treatment/therapy could be more effective under TNF-α inhibition. Both L. amazonensis-infected macrophages (in vitro model) and mice (in vivo model) were treated with a nuclear factor-κB (NF-κB) inhibitor and with Glucantime®, alone and in combined administrations. The in vitro amastigote counts, cytokines and nitrites' production were assessed after 48h incubation with the drugs. Paw lesion sizes and amastigote counts were also evaluated in vivo. Quantification of IL-1ß from the infected tissue was performed. In vitro results show that when infected macrophages were incubated with QNZ+Glucantime®, a greater clearance was observed for the amastigotes' growth and this was related to greater nitrite production compared to the group that was only infected. In vivo results show that mice that received the combined treatment had their paw lesion sizes and amastigote nests inside the macrophages greatly diminished, correlating with increased IL-1ß levels.