RESUMO
Introduction: Leishmaniasis comprises a complex group of diseases caused by protozoan parasites from the Leishmania genus, presenting a significant threat to human health. Infection starts by the release into the skin of metacyclic promastigote (MP) form of the parasite by an infected sand fly. Soon after their release, the MPs enter a phagocytic host cell. This study focuses on finding peptides that can inhibit MP-phagocytic host cell interaction. Methods: We used a phage display library to screen for peptides that bind to the surface of L. amazonensis (causative agent for cutaneous leishmaniasis) and L. infantum (causative agent for cutaneous and visceral leishmaniasis) MPs. Candidate peptide binding to the MP surface and inhibition of parasite-host cell interaction were tested in vitro. Peptide Inhibition of visceral leishmaniasis development was assessed in BALB/c mice. Results: The selected L. amazonensis binding peptide (La1) and the L. infantum binding peptide (Li1) inhibited 44% of parasite internalization into THP-1 macrophage-like cells in vitro. While inhibition of internalization by La1 was specific to L. amazonensis, Li1 was effective in inhibiting internalization of both parasite species. Importantly, Li1 inhibited L. infantum spleen and liver infection of BALB/c mice by 84%. Conclusion: We identified one peptide that specifically inhibits L. amazonensis MP infection of host cells and another that inhibits both, L. amazonensis and L. infantum, MP infection. Our findings suggest a promising path for the development of new treatments and prevention of leishmaniasis.
RESUMO
Leishmaniasis refers to a collection of diseases caused by protozoa from the Leishmania genus. These diseases, along with other parasitic afflictions, pose a significant public health issue, particularly given the escalating number of at-risk patients. This group includes immunocompromised individuals and those residing in impoverished conditions. The treatment of leishmaniasis is crucial, particularly in light of the mortality rate associated with nontreatment, which stands at 20-30,000 deaths per year globally. However, the therapeutic options currently available are limited, often ineffective, and potentially toxic. Consequently, the pursuit of new therapeutic alternatives is warranted. This study aims to design, synthesize, and evaluate the leishmanicidal activity of antimicrobial peptides functionalized with guanidine compounds and identify those with enhanced potency and selectivity against the parasite. Accordingly, three bioconjugates were obtained by using the solid-phase peptide synthesis protocol. Each proved to be more potent against intracellular amastigotes than their respective peptide or guanidine compounds alone and demonstrated higher selectivity to the parasites than to the host cells. Thus, the conjugation strategy employed with these compounds effectively contributes to the development of new molecules with leishmanicidal activity.
RESUMO
Leishmaniasis is a neglected disease that impacts more than one billion people in endemic areas of the globe. Several drawbacks are associated with the currently existing drugs for treatment such as low effectiveness, toxicity, and the emergence of resistant strains that demonstrate the importance of looking for novel therapeutic alternatives. Photodynamic therapy (PDT) is a promising novel alternative for cutaneous leishmaniasis treatment because its topical application avoids potential side effects generally associated with oral/parenteral application. A light-sensitive compound known as photosensitizer (PS) interacts with light and molecular oxygen to generate reactive oxygen species (ROS), which promote cell death by oxidative stress through PDT approaches. Here, for the first time, we demonstrate the antileishmanial effect of tetra-cationic porphyrins with peripheral Pt(II)- and Pd(II)-polypyridyl complexes using PDT. The isomeric tetra-cationic porphyrins in the meta positions, 3-PtTPyP, and 3-PdTPyP, exhibited the highest antiparasitic activity against promastigote (IC50-pro = 41.8 nM and 46.1 nM, respectively) and intracellular amastigote forms (IC50-ama = 27.6 nM and 38.8 nM, respectively) of L. amazonensis under white light irradiation (72 J cm-2) with high selectivity (SI > 50) for both forms of parasites regarding mammalian cells. In addition, these PS induced the cell death of parasites principally by a necrotic process in the presence of white light by mitochondrial and acidic compartments accumulation. This study showed that porphyrins 3-PtTPyP and 3-PdTPyP displayed a promising antileishmanial-PDT activity with potential application for cutaneous leishmaniasis treatment.
Assuntos
Antiprotozoários , Leishmaniose Cutânea , Fotoquimioterapia , Porfirinas , Humanos , Animais , Porfirinas/farmacologia , Porfirinas/uso terapêutico , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico , Fotoquimioterapia/métodos , Antiprotozoários/uso terapêutico , Leishmaniose Cutânea/tratamento farmacológico , MamíferosRESUMO
Leishmaniasis is a highly prevalent, yet neglected disease caused by protozoan parasites of the genus Leishmania. In the search for newer, safer, and more effective antileishmanial compounds, we herein present a study of the mode of action in addition to a detailed structural and biological characterization of LQOF-G6 [N-benzoyl-N'-benzyl-Nâ³-(4-tertbutylphenyl)guanidine]. X-ray crystallography and extensive NMR experiments revealed that LQOF-G6 nearly exclusively adopts the Z conformation stabilized by an intramolecular hydrogen bond. The investigated guanidine showed selective inhibitory activity on Leishmania major cysteine protease LmCPB2.8ΔCTE (CPB) with ~73% inhibition and an IC50-CPB of 6.0 µM. This compound did not show any activity against the mammalian homologues cathepsin L and B. LQOF-G6 has been found to be nontoxic toward both organs and several cell lines, and no signs of hepatotoxicity or nephrotoxicity were observed from the analysis of biochemical clinical plasma markers in the treated mice. Docking simulations and experimental NMR measurements showed a clear contribution of the conformational parameters to the strength of the binding in the active site of the enzyme, and thus fit the differences in the inhibition values of LQOF-G6 compared to the other guanidines. Furthermore, the resulting data render LQOF-G6 suitable for further development as an antileishmanial drug.
Assuntos
Cisteína Proteases , Leishmania major , Leishmaniose , Animais , Camundongos , Cisteína Proteases/metabolismo , Guanidina , Virulência , Leishmaniose/tratamento farmacológico , Mamíferos/metabolismoRESUMO
Gracilariales is a clade of florideophycean red macroalgae known for being the main source of agar. We present a de novo genome assembly and annotation of Gracilaria domingensis, an agarophyte alga with flattened thallus widely distributed along Central and South American Atlantic intertidal zones. In addition to structural analysis, an organizational comparison was done with other Rhodophyta genomes. The nuclear genome has 78 Mbp, with 11,437 predicted coding genes, 4,075 of which did not have hits in sequence databases. We also predicted 1,567 noncoding RNAs, distributed in 14 classes. The plastid and mitochondrion genome structures were also obtained. Genes related to agar synthesis were identified. Genes for type II galactose sulfurylases could not be found. Genes related to ascorbate synthesis were found. These results suggest an intricate connection of cell wall polysaccharide synthesis and the redox systems through the use of L-galactose in Rhodophyta. The genome of G. domingensis should be valuable to phycological and aquacultural research, as it is the first tropical and Western Atlantic red macroalgal genome to be sequenced.
Assuntos
Genoma Mitocondrial , Gracilaria , Rodófitas , Ágar/metabolismo , Galactose/metabolismo , Gracilaria/genética , Rodófitas/genética , Rodófitas/metabolismoRESUMO
The current treatment of leishmaniasis is based on a few drugs that present several drawbacks, such as high toxicity, difficult administration route, and low efficacy. These disadvantages raise the necessity to develop novel antileishmanial compounds allied with a comprehensive understanding of their mechanisms of action. Here, we elucidate the probable mechanism of action of the antileishmanial binuclear cyclopalladated complex [Pd(dmba)(µ-N3)]2 (CP2) in Leishmania amazonensis. CP2 causes oxidative stress in the parasite, resulting in disruption of mitochondrial Ca2+ homeostasis, cell cycle arrest at the S-phase, increasing the reactive oxygen species (ROS) production and overexpression of stress-related and cell detoxification proteins, and collapsing the Leishmania mitochondrial membrane potential, and promotes apoptotic-like features in promastigotes, leading to necrosis, or directs programmed cell death (PCD)-committed cells toward necrotic-like destruction. Moreover, CP2 reduces the parasite load in both liver and spleen in Leishmania infantum-infected hamsters when treated for 15 days with 1.5 mg/kg body weight/day CP2, expanding its potential application in addition to the already known effectiveness on cutaneous leishmaniasis for the treatment of visceral leishmaniasis, showing the broad spectrum of action of this cyclopalladated complex. The data presented here bring new insights into the CP2 molecular mechanisms of action, assisting the promotion of its rational modification to improve both safety and efficacy.
Assuntos
Antiprotozoários , Leishmania infantum , Leishmaniose Cutânea , Animais , Antiprotozoários/uso terapêutico , Cálcio/metabolismo , Morte Celular , Leishmaniose Cutânea/tratamento farmacológico , Macrófagos , Camundongos , Camundongos Endogâmicos BALB C , MitocôndriasRESUMO
Natural products have been largely explored as treatments for leishmaniasis, neglected diseases with few toxic therapeutic options, as scaffolds for the development of new drugs. Herein, derivatives from the aerial parts of Baccharis trimera (Less.) DC (extract and its fractions) were evaluated against Leishmania amazonensis and macrophage cells. The ethyl acetate extract was fractionated by solid-phase extraction, resulting in eight fractions (F1-F8). Fractions F3-4 were further separated into 149 subfractions; subfraction 148 (IC50-PRO = 1.56 ± 0.1 µg mL-1) was selected for purification and constituent(s) characterization by high-performance liquid chromatography, as well as 1H and 13C nuclear magnetic resonance spectroscopy. The flavonoid eupatorin (3',5-dihydroxy-4',6,7-trimethoxyflavone) was identified. This compound was 3.7 times more effective against intracellular amastigotes (IC50-AMA = 1.6 ± 0.1 µM) than amphotericin B and presented low cytotoxicity (CC50 > 100 µM), being almost 62 times more selective for the parasite, showing great potential in drug development for cutaneous leishmaniasis treatment.
Assuntos
Antiprotozoários , Baccharis , Leishmania mexicana , Leishmaniose Cutânea , Antiprotozoários/farmacologia , Baccharis/química , Flavonoides/análise , Leishmaniose Cutânea/tratamento farmacológico , Extratos Vegetais/química , Folhas de Planta/químicaRESUMO
Leishmaniasis is a neglected disease that affects 12 million people living mainly in developing countries. Herein, 24 new N-oxide-containing compounds were synthesized followed by in vitro and in vivo evaluation of their antileishmanial activity. Compound 4f, a furoxan derivative, was particularly remarkable in this regard, with EC50 value of 3.6 µM against L. infantum amastigote forms and CC50 value superior to 500 µM against murine peritoneal macrophages. In vitro studies suggested that 4f may act by a dual effect, by releasing nitric oxide after biotransformation and by inhibiting cysteine protease CPB (IC50: 4.5 µM). In vivo studies using an acute model of infection showed that compound 4f at 7.7 mg/Kg reduced ~90% of parasite burden in the liver and spleen of L. infantum-infected BALB/c mice. Altogether, these outcomes highlight furoxan 4f as a promising compound for further evaluation as an antileishmanial agent.
Assuntos
Antiprotozoários/farmacologia , Desenho de Fármacos , Leishmania infantum/efeitos dos fármacos , Óxidos/farmacologia , Animais , Antiprotozoários/síntese química , Antiprotozoários/química , Biomarcadores/metabolismo , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Ligantes , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/parasitologia , Masculino , Camundongos , Simulação de Acoplamento Molecular , Óxido Nítrico/análise , Nitritos/análise , Oxidiazóis/síntese química , Oxidiazóis/química , Óxidos/síntese química , Óxidos/química , Carga Parasitária , Pichia/metabolismo , Espectroscopia de Prótons por Ressonância Magnética , Proteínas de Protozoários/metabolismoRESUMO
Leishmaniasis is a group of diseases that have limited and high toxic therapeutic options. Herein, we evaluated the antileishmanial potential and cytotoxicity of hexanic extract obtained from the Antarctic brown alga Ascoseira mirabilis using bioguided fractionation against Leishmania amazonensis and murine macrophages, which was fractionated by SPE, yielding seven fractions (F1-F7). The fraction F6 showed good anti-amastigote activity (IC50 = 73.4 ± 0.4 µg mL-1) and low cytotoxicity (CC50 > 100 µg mL-1). Thus, in order to identify the bioactive constituent(s) of F6, the fraction was separated in a semipreparative HPLC, yielding four fractions (F6.1-F6.4). F6.2 was the most bioactive fraction (IC50 = 66.5 ± 4.5 µg mL-1) and GC-MS analyses revealed that the compounds octadecane, propanoic acid, 1-monomyristin and azelaic acid correspond to 61% of its composition. These data show for the first time the antileishmanial potential of the Antarctic alga A. mirabilis.
Assuntos
Antiprotozoários , Leishmania mexicana , Leishmaniose , Mirabilis , Phaeophyceae , Animais , Antiprotozoários/farmacologia , Leishmaniose/tratamento farmacológico , Camundongos , Camundongos Endogâmicos BALB C , Extratos Vegetais/uso terapêuticoRESUMO
Leishmaniasis is a serious and neglected disease that affects 14 million people around the World. The currently available drugs for treatment present several drawbacks such as low efficacy and severe side effects, contributing to patients' low compliance. Photodynamic therapy (PDT) is rising as a promising treatment of cutaneous leishmaniasis, mainly considering its topical administration that circumvents any potential adverse effects commonly related to oral/parenteral administration. PDT depends on the interaction between a light-sensitive compound (photosensitizer - PS), light and molecular oxygen. The reaction generates reactive oxygen species (ROS) which induce cell death by oxidative stress. The main goal of this study is to demonstrate the antileishmanial effect of three chlorin derivatives (CHL-OH-A, CHL-OH-B, CHL-TRISMA) using PDT, as well as to investigate their cell death pathway on Leishmania amazonensis promastigote forms after chlorin-PDT application. The chlorin derivatives herein studied did not exhibit aggregates in aqueous medium and showed fast accumulation in Leishmania acidic compartments. CHL-OH-A exhibited the highest antiparasitic activity at 24 h (0.33 µmol L-1) and 48 h (0.14 µmol L-1) after irradiation at 660 nm (6.0 Jcm-2). CHL-OH-A, CHL-OH-B and CHL-TRISMA molecules induced the cell death of parasites mainly by an apoptotic-like process in the presence of light. These chlorin derivatives are 80-fold more active against Leishmania when compared to other PSs reported in the literature. In this study, we have shown that these amphiphilic chlorins, and in particular, CHL-OH-A, exert an interesting leishmanicidal activity suggesting that the use of these PSs associated with PDT could be a promising strategy for treatment of cutaneous leishmaniasis.