Rubem Menna-barreto | Fundação Oswaldo Cruz (original) (raw)
Papers by Rubem Menna-barreto
New Journal of Chemistry, 2019
A-ring selenation of naphthoquinones and anthraquinones is reported. The reaction proceeds in the... more A-ring selenation of naphthoquinones and anthraquinones is reported. The reaction proceeds in the presence of a copper source, and provides an efficient and general method for preparing selenium-based quinones with trypanocidal activity.
After a detailed evaluation, analyzing the scientific relevance of these interesting findings, th... more After a detailed evaluation, analyzing the scientific relevance of these interesting findings, this manuscript should be accepted for publication. The text is very clear and well-written and the hypothesis is ok. It is a huge study comparing the host cell responses of three different macrophages to the infection with T. gondii. The analysis of macrophages infection by this parasite is very well-known, and the comparisons among these cells per si, is not represent too much novelty. However, the molecular approach used to evaluate the biological role of GBPs during the infection is very elegant and criterious. The authors performed many important controls, increasing the reliability of the data. In the methods section, some information about the infection is lacking. What is the MOI used? "MOI of 1" is written… T. gondii is a very aggressive, and the results did not suggest a very high infection. Can be possible that a soluble factor from HFF cultures is co-stimulating the macrophages? For sure, there is no doubt that this manuscript is a relevant contribution to the literature. Congratulations.
Additional file 1: Figure S1. Intermolecular interactions obtained from the molecular docking pos... more Additional file 1: Figure S1. Intermolecular interactions obtained from the molecular docking pose of the assayed compounds and HIV aspartyl peptidase. We selected three compounds with the highest hits from the molecular docking simulation: saquinavir, atazanavir, and nefilnavir (A–C). In A, the picture on the square represents the superposition of co-crystal (green) and redocked saquinavir structures (orange).
Frontiers in Cellular and Infection Microbiology, 2022
The balance between the protozoans virulence and host immune responses (invertebrates and/or vert... more The balance between the protozoans virulence and host immune responses (invertebrates and/or vertebrates) is crucial for the successful completion of the life cycle of these parasites in their hosts. Strategies such as macromolecules secretion, resistance to oxidative species, and silencing of macrophages, among many others, are applied by the parasites to evade host defenses. In this context, redox balance and biochemical mechanisms implicated by the parasitic protozoans represent a promising starting point for the development of novel anti-parasitic drugs and vaccines, and for testing their efficacy in preclinical and clinical trials. Reactive oxygen species (ROS) participate in regulating the protozoans' infection asis extensively reported in the literature. Antioxidant enzymes expressed by the parasites play a biological role as virulence factors, contributing to the complexity of the parasite-host relationship. In this Research Topic, cellular, molecular, and biochemical aspects of the interactions of pathogenic protozoans and their hosts with a focus on parasite survival, dissemination, and evasion of host immune responses, and the suggestion of novel strategies for parasite elimination were addressed. This Research Topic comprises six articles, three of which were original contributions. Velaśquez et al. from Justus Liebig Universität Gießen (Giessen, Germany) presented the concept of macromeront formation by the apicomplexan protozoa Eimeria bovis, a parasite of veterinary importance, in the primary host endothelial cells. The authors showed that E. bovis promoted an important alteration in the glycolytic metabolism and mitochondrial plasticity of the host cells. Increased glucose and pyruvate consumption associated with high lactate production indicated a pivotal role of glycolysis in infected cells, data confirmed by the use of glycolytic inhibitors. Increased ROS generation and altered membrane potential suggests mitochondrial dysfunction in macromeront-carrying host cells. In another contribution developed by the researchers at the Universidad de la República (Montevideo, Uruguay), Specker et al. showed the role of mitochondrial peroxiredoxin (MPX) of the parasite Trypanosoma cruzi, the causative agent of Chagas disease, in determining the infectivity in macrophages and attenuating the toxicity of the anti-T. cruzi drug nifurtimox. Parasites with enhanced content of MPX were more resistant to nifurtimox and this was not due to the efficient peroxidase activity but instead a new holdase activity of this peroxiredoxin. MPX holdase activity was characterized in this study, and shown to increase in parasites stressed with drug challenge (nifurtimox and benznidazole) and temperature (37°C). The authors' findings point to a parasite response to protein unfolding and degradation, highlighting the importance of maintaining parasite proteastasis. The relative contribution of peroxidase versus holdase activity in macrophage infection was evaluated using an inhibitor of the peroxidase but not holdase
Supplementary Methods. (DOCX 16Â kb)
Figure S2. Mean interquartile range, median and yield of vesicles per cell obtained from medium d... more Figure S2. Mean interquartile range, median and yield of vesicles per cell obtained from medium depleted of FBS (Without FBS) or containing EV-free FBS (with FBS). *Significantly different from "Without FBS", p
BioMed research international, 2014
The pathogenic trypanosomatids Trypanosoma brucei, Trypanosoma cruzi, and Leishmania spp. are the... more The pathogenic trypanosomatids Trypanosoma brucei, Trypanosoma cruzi, and Leishmania spp. are the causative agents of African trypanosomiasis, Chagas disease, and leishmaniasis, respectively. These diseases are considered to be neglected tropical illnesses that persist under conditions of poverty and are concentrated in impoverished populations in the developing world. Novel efficient and nontoxic drugs are urgently needed as substitutes for the currently limited chemotherapy. Trypanosomatids display a single mitochondrion with several peculiar features, such as the presence of different energetic and antioxidant enzymes and a specific arrangement of mitochondrial DNA (kinetoplast DNA). Due to mitochondrial differences between mammals and trypanosomatids, this organelle is an excellent candidate for drug intervention. Additionally, during trypanosomatids' life cycle, the shape and functional plasticity of their single mitochondrion undergo profound alterations, reflecting adapta...
Parasitology Research, 2008
In the search for new therapeutic agents for Chagas' disease, we screened extracts obtained from ... more In the search for new therapeutic agents for Chagas' disease, we screened extracts obtained from the Brazilian plant Pterodon pubescens found commercially in the medicinal flora market. We investigated the potential trypanocidal effect of the oleaginous ethanolic extract of P. pubescens seeds and its fractions (PF1, PF1.1, PF1.2, and PF1.3) and of geranylgeraniol (GG-OH), the sole component of the hexane fraction (PF1.2). In experiments with bloodstream trypomastigotes of Trypanosoma cruzi, performed at 37°C in culture medium, PF1.2 and GG-OH showed similar potency, while the oleaginous extract from P. pubescens seeds and the other fractions were about three times less active. GG-OH inhibited the proliferation of intracellular amastigotes, at concentrations which do not affect the mammalian host cell. Transmission electron microscopy and flow cytometry analysis indicate the mitochondrion, an organelle that plays a central role in apoptosis, of both epimastigotes and of trypomastigotes as the major target of GG-OH. On the other hand, the ultrastructural images of the endoplasmic reticulum profiles, myelin-like figures, and concentric membranous arrangements inside damaged mitochondrion are suggestive of an autophagic pathway leading to parasite death. Because the different forms of cell death share some morphological features such as mitochondrial collapse, further studies are needed to disclose the trypanocidal action of GG-OH.
Journal of the Brazilian Chemical Society, 2014
A doença de Chagas causada pelo Trypanosoma cruzi afeta cerca de oito milhões de pessoas em paíse... more A doença de Chagas causada pelo Trypanosoma cruzi afeta cerca de oito milhões de pessoas em países em desenvolvimento, sendo classificada como uma doença tropical negligenciada pela Organização Mundial da Saúde. A quimioterapia disponível para esta doença é baseada em dois nitro-heterocíclicos, nifurtimox e benznidazol, ambos com graves efeitos colaterais e eficácia variável, e assim novos medicamentos visando um tratamento mais eficiente são necessários com urgência. Nos últimos 20 anos, temos desenvolvido em colaboração com grupos focados em química medicinal, um programa de quimioterapia experimental da doença de Chagas, investigando a eficácia, seletividade, toxicidade, alvos celulares e mecanismos de ação de diferentes classes de compostos sobre T. cruzi. Neste artigo, apresentamos uma visão geral desses estudos, enfocando protótipos naftoquinoidais e derivados, examinando a sua síntese, a atividade e mecanismo de ação, o que foi realizado e o que precisa ser abordado, avaliando e discutindo possíveis melhorias. Esta mini-revisão discute nosso esforço continuado visando a caracterização biológica e a síntese de compostos naftoquinoidais, auxiliando no desenvolvimento de um novo arsenal de drogas candidatas com eficácia contra o T. cruzi. Chagas disease is caused by the parasite Trypanosoma cruzi and affects approximately eight million individuals in the developing world; it is also classified as a neglected tropical disease by the World Health Organization. The available therapy for this disease is based on two nitroheterocycles, nifurtimox and benznidazole, both of which exhibit severe side effects and variable efficacy; therefore, new drugs and better treatment schedules are urgently needed. For the past 20 years, we have been collaborating with groups focused on medicinal chemistry to produce experimental therapies for Chagas disease by investigating the efficacy, selectivity, toxicity, cellular targets and mechanisms of action of different classes of compounds against T. cruzi. In this report, we present an overview of these studies, focusing on naphthoquinonoid prototypes and discuss their synthesis, activity and mechanisms of action. Furthermore, we summarise the research that has been performed to date and suggest future research directions while assessing and discussing potential improvements. This mini-review discusses our continued efforts toward the biological characterisation and synthesis of naphthoquinoidal compounds, aiming to contribute to the development of a new arsenal of candidate drugs that exhibit effective anti-T. cruzi activity
Parasitology, 2009
SUMMARYIn a screening of 65 derivatives of natural quinones using bloodstream trypomastigotes of ... more SUMMARYIn a screening of 65 derivatives of natural quinones using bloodstream trypomastigotes of Trypanosoma cruzi, the 3 naphthoimidazoles derived from β-lapachone – N1, N2 and N3 – were selected as the most active. Investigation of their mode of action led to the characterization of mitochondrion, reservosomes and DNA as their main targets, and stimulated further studies on death pathways. Ultrastructural analysis revealed both autophagic (autophagosomes) and apoptotic-like (membrane blebbing) phenotypes. Flow cytometry analysis showed, in N2-treated trypomastigotes, a small increase of phosphatidylserine exposure, and a large increase in the percentage of necrosis, caused by N1 or N2. These death phenotypes were not detected in treated epimastigotes. The strong increase in labelling of monodansyl cadaverine, the inhibition of the death process by wortmannin or 3-methyladenine, the overexpression of ATG genes in treated epimastigotes, together with ultrastructural evidence point t...
Parasitology, 2011
SUMMARYChagas' disease, caused by the protozoan Trypanosoma cruzi, represents a serious healt... more SUMMARYChagas' disease, caused by the protozoan Trypanosoma cruzi, represents a serious health problem in Latin America, and the available chemotherapy, which is based on 2 nitro-derivatives, is not satisfactory. In folk medicine, natural products including naphthoquinones have been employed for the treatment of different parasitic diseases. In the pursuit of alternative drugs for Chagas' disease, we investigated the mechanism of action of the triazolic naphthoquinone (TN; 2,2-dimethyl-3-(4-phenyl-1H-1,2,3-triazol-1-yl)-2,3-dihydronaphtho[1,2-b]furan-4,5-dione), which is the most active compound against T. cruzi trypomastigotes among a series of naphthofuranquinones. TN was active against the 3 parasite forms producing a dose-dependent inhibitory effect. In epimastigotes, TN induced reservosome disruption, flagellar blebbing, Golgi disorganization, the presence of cytosolic concentric membrane structures and abnormal multiflagellar parasites. The treatment also led to the ap...
Medicinal Chemistry, 2007
This study describes the design, synthesis and trypanocidal evaluation of new azaheterocyclic der... more This study describes the design, synthesis and trypanocidal evaluation of new azaheterocyclic derivatives (4-8). These compounds were designed as megazol (1) analogs based on bioisosterism tools and were synthesized to investigate the possible pharmacophoric contribution of the 1,2,4-triazole nucleus, the position of the heterocyclic nucleus and presence of the nitro group, to the activity against the bloodstream trypomastigote forms of Trypanosoma cruzi. The most potent compound was 6, a nitro derivative obtained by substitution of a thiadiazole by a triazole ring and by moving the nitro group from C-5 position, as in 1, to the C-4 position. Finally, we have used semi-empirical theoretical calculations to discuss the correlation of some stereo electronic properties with biological activity in an attempt to understand the possible mechanism of action of the designed series of compounds.
Journal of Proteomics, 2010
Chagas' disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America, which cu... more Chagas' disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America, which current treatment presents variable efficacy and serious side effects. A previous screening of naphthoquinone derivatives pointed to the naphthoimidazoles N1, N2 and N3 as the most active compounds against T. cruzi. In this study, a proteomic approach was employed to identify proteins involved in the N1, N2 and N3 trypanocidal activity. In epimastigotes, the naphthoimidazoles are involved in multiple mechanisms: (a) redox metabolism; (b) energy production; (c) ergosterol biosynthesis; (d) cytoskeleton assembly; (e) protein metabolism and biosynthesis; and (f) chaperones modulation. They induce an imbalance in crucial pathways of the parasite, leading to the loss of metabolic homeostasis and T. cruzi death.
Journal of Antimicrobial Chemotherapy, 2005
Investigation of the mode of action of the naphthoimidazole N1, obtained from the reaction of b-l... more Investigation of the mode of action of the naphthoimidazole N1, obtained from the reaction of b-lapachone with benzaldehyde, which among 45 semi-synthetic derivatives of naphthoquinones isolated from Tabebuia sp. was one of the most active compounds against Trypanosoma cruzi trypomastigotes. Methods: Quantification of the effect of N1 against the proliferative forms of T. cruzi, and investigation of potential targets in the parasite using electron microscopy and flow cytometry techniques. Results: N1 presented the following order of activity: amastigotes > trypomastigotes > epimastigotes. The effect on intracellular forms was 25 times higher than on macrophages and heart muscle cells. N1-treated parasites presented an abnormal chromatin condensation and mitochondrial damage. In epimastigotes, alterations of reservosomes were observed, and in trypomastigotes, a decrease in the electron density of acidocalcisomes was observed. In epimastigotes, the naphthoimidazole inhibited the activity of succinate cytochrome c reductase. Labelling with rhodamine 123 or Acridine Orange was decreased in both forms treated with N1. Conclusions: The results suggest that epimastigotes, reservosomes, mitochondrion, and nucleus contain N1 targets. In trypomastigotes, in which reservosomes are absent, the organelles affected by the compound were also the mitochondrion and nucleus, as well as acidocalcisomes, in which the decrease in electron density could be due to the use of polyphosphate as an alternative energy supply.
Free Radical Biology and Medicine, 2009
Despite ongoing efforts, the current treatment for Chagas disease is still unsatisfactory, mainly... more Despite ongoing efforts, the current treatment for Chagas disease is still unsatisfactory, mainly because of the severe side effects and variable efficacy of the available nitroheterocycles. Our group has been assaying natural quinones isolated from Brazilian flora, and their derivatives, as alternative chemotherapeutic agents against Trypanosoma cruzi. From C-allyl lawsone three naphthofuranquinones were synthesized, which were active against trypomastigotes and epimastigotes. Here, we further investigated the activity and the mechanisms of action of these quinones. They exhibited powerful effects on intracellular amastigotes, presenting low toxicity to the host cells. Ultrastructural analyses of treated epimastigotes and trypomastigotes indicated a potent effect of the three naphthofuranquinones on the parasite mitochondrion, which appeared drastically swollen and with a washed-out matrix profile. Fluorescence-activated cell sorting analysis of rhodamine 123-stained T. cruzi showed that the three naphthofuranquinones caused a potent dose-dependent collapse of the mitochondrial membrane potential, especially in the epimastigote form. Naphthofuranquinones also decreased specifically mitochondrial complex I-III activity in both epimastigotes and trypomastigotes, parallel to a reduction in succinate-induced oxygen consumption. Mitochondrial hydrogen peroxide formation was also increased in epimastigotes after treatment with the naphthofuranquinones. Our results indicate that the trypanocidal action of the naphthofuranquinones is associated with mitochondrial dysfunction, leading to increased reactive oxygen species generation and parasite death.
![Research paper thumbnail of Naphthoquinoidal [1,2,3]-triazole, a new structural moiety active against Trypanosoma cruzi](https://attachments.academia-assets.com/87200829/thumbnails/1.jpg)
](European Journal of Medicinal Chemistry, 2008
[1,2,3]-Triazole derivatives of nor-b-lapachone were synthesized and assayed against the infectiv... more [1,2,3]-Triazole derivatives of nor-b-lapachone were synthesized and assayed against the infective bloodstream trypomastigote form of Trypanosoma cruzi, the etiological agent of Chagas disease. All the derivatives were more active than the original quinones, with IC 50 /1 day values in the range of 17 to 359 mM, the apolar phenyl substituted triazole 6 being the most active compound. These triazole derivatives of nor-b-lapachone emerge as interesting new lead compounds in drug development for Chagas disease.
![Research paper thumbnail of Studies on the trypanocidal activity of semi-synthetic pyran[b-4,3]naphtho[1,2-d]imidazoles from β-lapachone](https://attachments.academia-assets.com/87200769/thumbnails/1.jpg)
](European Journal of Medicinal Chemistry, 2004
We synthesized new naphthoimidazoles from b-lapachone with an aromatic moiety linked to the imida... more We synthesized new naphthoimidazoles from b-lapachone with an aromatic moiety linked to the imidazole ring, using phenylic and heterocyclic aldehydes. The most active compound against Trypanosoma cruzi had a p-methyl group linked to the phenyl ring, presenting an EC 50 value of 15.5 ± 2.9 µM. No reliable correlation could be established with the biological activity and the structure of in the phenylic series. For the heterocyclic series, activity was associated with a three bond-distance from nitrogen to the imidazole ring, in accordance with our previous work.
![Research paper thumbnail of Studies on the trypanocidal activity of semi-synthetic pyran[b-4,3]naphtho[1,2-d]imidazoles from β-lapachone](https://attachments.academia-assets.com/87200708/thumbnails/1.jpg)
](European Journal of Medicinal Chemistry, 2004
We synthesized new naphthoimidazoles from b-lapachone with an aromatic moiety linked to the imida... more We synthesized new naphthoimidazoles from b-lapachone with an aromatic moiety linked to the imidazole ring, using phenylic and heterocyclic aldehydes. The most active compound against Trypanosoma cruzi had a p-methyl group linked to the phenyl ring, presenting an EC 50 value of 15.5 ± 2.9 µM. No reliable correlation could be established with the biological activity and the structure of in the phenylic series. For the heterocyclic series, activity was associated with a three bond-distance from nitrogen to the imidazole ring, in accordance with our previous work.
Chemico-Biological Interactions, 2009
In order to elucidate the effect on mammal systems of new derivatives from 2-hydroxy-3-allylnapht... more In order to elucidate the effect on mammal systems of new derivatives from 2-hydroxy-3-allylnaphthoquinone, ␣-iodinated naphthofuranquinone (NPPN-3223), -iodinated naphthofuranquinone (NPPN-3222) and -methyl naphthofuranquinone (NPPN-3226) synthesized as possible trypanocidal agents, their effect on rat liver microsomal lipid peroxidation was investigated. They (a) inhibited NADPH-dependent, iron-catalyzed microsomal rat liver lipid peroxidation; (b) did not inhibit the tertbutyl hydroperoxide-dependent lipid peroxidation; (c) did not inhibit ascorbate-lipid peroxidation with the exception of NPPN-3226 which did inhibit it; (d) stimulated NADPH oxidation and microsomal oxygen uptake; (e) increased superoxide anion formation by NADPH-supplemented microsomes and (f) stimulated ascorbate oxidation. The three drugs were reduced to their seminaphthofuranquinone radical by the liver NADPH-P450 reductase system, as detected by ESR measurements. These results support the hypothesis that naphthofuranquinones reduction by microsomal NADPH-P450 reductase and semiquinone oxidation by molecular oxygen diverts electrons, preventing microsomal lipid peroxidation. In addition, hydroquinones and/or semiquinones formed by naphthofuranquinones reduction would be capable of lipid peroxidation inhibition and on interacting with the lipid peroxide radicals can lead to an antioxidant effect as we suggested for NPPN-3226 in close agreement to the inhibition of ascorbate-lipid peroxidation. Due to the properties of these molecules and their incoming structure developments, naphthofuranquinones would be considered as potentially promising therapeutic agents, mainly against Chagas disease.
Bioorganic & Medicinal Chemistry, 2008
We report herein a straightforward and efficient one-step reaction to prepare new nor-b-lapachone... more We report herein a straightforward and efficient one-step reaction to prepare new nor-b-lapachone derivatives tethered with phenylthio groups at position 3 of the furan ring. We have screened the compounds on bloodstream trypomastigotes of Trypanosoma cruzi, the causative agent of Chagas disease, aimed at finding a new prototype with high trypanocidal activity. The new compounds possess a broad range of activity (IC 50 /24 h from 9.2 to 182.7 lM), higher than the original quinone (391.5 lM) and four of them higher than standard drug benznidazole (103.6 lM). The most active was compound 13b (9.2 lM), being 11 times active than benznidazole and the less toxic derivative to heart muscle cells.
New Journal of Chemistry, 2019
A-ring selenation of naphthoquinones and anthraquinones is reported. The reaction proceeds in the... more A-ring selenation of naphthoquinones and anthraquinones is reported. The reaction proceeds in the presence of a copper source, and provides an efficient and general method for preparing selenium-based quinones with trypanocidal activity.
After a detailed evaluation, analyzing the scientific relevance of these interesting findings, th... more After a detailed evaluation, analyzing the scientific relevance of these interesting findings, this manuscript should be accepted for publication. The text is very clear and well-written and the hypothesis is ok. It is a huge study comparing the host cell responses of three different macrophages to the infection with T. gondii. The analysis of macrophages infection by this parasite is very well-known, and the comparisons among these cells per si, is not represent too much novelty. However, the molecular approach used to evaluate the biological role of GBPs during the infection is very elegant and criterious. The authors performed many important controls, increasing the reliability of the data. In the methods section, some information about the infection is lacking. What is the MOI used? "MOI of 1" is written… T. gondii is a very aggressive, and the results did not suggest a very high infection. Can be possible that a soluble factor from HFF cultures is co-stimulating the macrophages? For sure, there is no doubt that this manuscript is a relevant contribution to the literature. Congratulations.
Additional file 1: Figure S1. Intermolecular interactions obtained from the molecular docking pos... more Additional file 1: Figure S1. Intermolecular interactions obtained from the molecular docking pose of the assayed compounds and HIV aspartyl peptidase. We selected three compounds with the highest hits from the molecular docking simulation: saquinavir, atazanavir, and nefilnavir (A–C). In A, the picture on the square represents the superposition of co-crystal (green) and redocked saquinavir structures (orange).
Frontiers in Cellular and Infection Microbiology, 2022
The balance between the protozoans virulence and host immune responses (invertebrates and/or vert... more The balance between the protozoans virulence and host immune responses (invertebrates and/or vertebrates) is crucial for the successful completion of the life cycle of these parasites in their hosts. Strategies such as macromolecules secretion, resistance to oxidative species, and silencing of macrophages, among many others, are applied by the parasites to evade host defenses. In this context, redox balance and biochemical mechanisms implicated by the parasitic protozoans represent a promising starting point for the development of novel anti-parasitic drugs and vaccines, and for testing their efficacy in preclinical and clinical trials. Reactive oxygen species (ROS) participate in regulating the protozoans' infection asis extensively reported in the literature. Antioxidant enzymes expressed by the parasites play a biological role as virulence factors, contributing to the complexity of the parasite-host relationship. In this Research Topic, cellular, molecular, and biochemical aspects of the interactions of pathogenic protozoans and their hosts with a focus on parasite survival, dissemination, and evasion of host immune responses, and the suggestion of novel strategies for parasite elimination were addressed. This Research Topic comprises six articles, three of which were original contributions. Velaśquez et al. from Justus Liebig Universität Gießen (Giessen, Germany) presented the concept of macromeront formation by the apicomplexan protozoa Eimeria bovis, a parasite of veterinary importance, in the primary host endothelial cells. The authors showed that E. bovis promoted an important alteration in the glycolytic metabolism and mitochondrial plasticity of the host cells. Increased glucose and pyruvate consumption associated with high lactate production indicated a pivotal role of glycolysis in infected cells, data confirmed by the use of glycolytic inhibitors. Increased ROS generation and altered membrane potential suggests mitochondrial dysfunction in macromeront-carrying host cells. In another contribution developed by the researchers at the Universidad de la República (Montevideo, Uruguay), Specker et al. showed the role of mitochondrial peroxiredoxin (MPX) of the parasite Trypanosoma cruzi, the causative agent of Chagas disease, in determining the infectivity in macrophages and attenuating the toxicity of the anti-T. cruzi drug nifurtimox. Parasites with enhanced content of MPX were more resistant to nifurtimox and this was not due to the efficient peroxidase activity but instead a new holdase activity of this peroxiredoxin. MPX holdase activity was characterized in this study, and shown to increase in parasites stressed with drug challenge (nifurtimox and benznidazole) and temperature (37°C). The authors' findings point to a parasite response to protein unfolding and degradation, highlighting the importance of maintaining parasite proteastasis. The relative contribution of peroxidase versus holdase activity in macrophage infection was evaluated using an inhibitor of the peroxidase but not holdase
Supplementary Methods. (DOCX 16Â kb)
Figure S2. Mean interquartile range, median and yield of vesicles per cell obtained from medium d... more Figure S2. Mean interquartile range, median and yield of vesicles per cell obtained from medium depleted of FBS (Without FBS) or containing EV-free FBS (with FBS). *Significantly different from "Without FBS", p
BioMed research international, 2014
The pathogenic trypanosomatids Trypanosoma brucei, Trypanosoma cruzi, and Leishmania spp. are the... more The pathogenic trypanosomatids Trypanosoma brucei, Trypanosoma cruzi, and Leishmania spp. are the causative agents of African trypanosomiasis, Chagas disease, and leishmaniasis, respectively. These diseases are considered to be neglected tropical illnesses that persist under conditions of poverty and are concentrated in impoverished populations in the developing world. Novel efficient and nontoxic drugs are urgently needed as substitutes for the currently limited chemotherapy. Trypanosomatids display a single mitochondrion with several peculiar features, such as the presence of different energetic and antioxidant enzymes and a specific arrangement of mitochondrial DNA (kinetoplast DNA). Due to mitochondrial differences between mammals and trypanosomatids, this organelle is an excellent candidate for drug intervention. Additionally, during trypanosomatids' life cycle, the shape and functional plasticity of their single mitochondrion undergo profound alterations, reflecting adapta...
Parasitology Research, 2008
In the search for new therapeutic agents for Chagas' disease, we screened extracts obtained from ... more In the search for new therapeutic agents for Chagas' disease, we screened extracts obtained from the Brazilian plant Pterodon pubescens found commercially in the medicinal flora market. We investigated the potential trypanocidal effect of the oleaginous ethanolic extract of P. pubescens seeds and its fractions (PF1, PF1.1, PF1.2, and PF1.3) and of geranylgeraniol (GG-OH), the sole component of the hexane fraction (PF1.2). In experiments with bloodstream trypomastigotes of Trypanosoma cruzi, performed at 37°C in culture medium, PF1.2 and GG-OH showed similar potency, while the oleaginous extract from P. pubescens seeds and the other fractions were about three times less active. GG-OH inhibited the proliferation of intracellular amastigotes, at concentrations which do not affect the mammalian host cell. Transmission electron microscopy and flow cytometry analysis indicate the mitochondrion, an organelle that plays a central role in apoptosis, of both epimastigotes and of trypomastigotes as the major target of GG-OH. On the other hand, the ultrastructural images of the endoplasmic reticulum profiles, myelin-like figures, and concentric membranous arrangements inside damaged mitochondrion are suggestive of an autophagic pathway leading to parasite death. Because the different forms of cell death share some morphological features such as mitochondrial collapse, further studies are needed to disclose the trypanocidal action of GG-OH.
Journal of the Brazilian Chemical Society, 2014
A doença de Chagas causada pelo Trypanosoma cruzi afeta cerca de oito milhões de pessoas em paíse... more A doença de Chagas causada pelo Trypanosoma cruzi afeta cerca de oito milhões de pessoas em países em desenvolvimento, sendo classificada como uma doença tropical negligenciada pela Organização Mundial da Saúde. A quimioterapia disponível para esta doença é baseada em dois nitro-heterocíclicos, nifurtimox e benznidazol, ambos com graves efeitos colaterais e eficácia variável, e assim novos medicamentos visando um tratamento mais eficiente são necessários com urgência. Nos últimos 20 anos, temos desenvolvido em colaboração com grupos focados em química medicinal, um programa de quimioterapia experimental da doença de Chagas, investigando a eficácia, seletividade, toxicidade, alvos celulares e mecanismos de ação de diferentes classes de compostos sobre T. cruzi. Neste artigo, apresentamos uma visão geral desses estudos, enfocando protótipos naftoquinoidais e derivados, examinando a sua síntese, a atividade e mecanismo de ação, o que foi realizado e o que precisa ser abordado, avaliando e discutindo possíveis melhorias. Esta mini-revisão discute nosso esforço continuado visando a caracterização biológica e a síntese de compostos naftoquinoidais, auxiliando no desenvolvimento de um novo arsenal de drogas candidatas com eficácia contra o T. cruzi. Chagas disease is caused by the parasite Trypanosoma cruzi and affects approximately eight million individuals in the developing world; it is also classified as a neglected tropical disease by the World Health Organization. The available therapy for this disease is based on two nitroheterocycles, nifurtimox and benznidazole, both of which exhibit severe side effects and variable efficacy; therefore, new drugs and better treatment schedules are urgently needed. For the past 20 years, we have been collaborating with groups focused on medicinal chemistry to produce experimental therapies for Chagas disease by investigating the efficacy, selectivity, toxicity, cellular targets and mechanisms of action of different classes of compounds against T. cruzi. In this report, we present an overview of these studies, focusing on naphthoquinonoid prototypes and discuss their synthesis, activity and mechanisms of action. Furthermore, we summarise the research that has been performed to date and suggest future research directions while assessing and discussing potential improvements. This mini-review discusses our continued efforts toward the biological characterisation and synthesis of naphthoquinoidal compounds, aiming to contribute to the development of a new arsenal of candidate drugs that exhibit effective anti-T. cruzi activity
Parasitology, 2009
SUMMARYIn a screening of 65 derivatives of natural quinones using bloodstream trypomastigotes of ... more SUMMARYIn a screening of 65 derivatives of natural quinones using bloodstream trypomastigotes of Trypanosoma cruzi, the 3 naphthoimidazoles derived from β-lapachone – N1, N2 and N3 – were selected as the most active. Investigation of their mode of action led to the characterization of mitochondrion, reservosomes and DNA as their main targets, and stimulated further studies on death pathways. Ultrastructural analysis revealed both autophagic (autophagosomes) and apoptotic-like (membrane blebbing) phenotypes. Flow cytometry analysis showed, in N2-treated trypomastigotes, a small increase of phosphatidylserine exposure, and a large increase in the percentage of necrosis, caused by N1 or N2. These death phenotypes were not detected in treated epimastigotes. The strong increase in labelling of monodansyl cadaverine, the inhibition of the death process by wortmannin or 3-methyladenine, the overexpression of ATG genes in treated epimastigotes, together with ultrastructural evidence point t...
Parasitology, 2011
SUMMARYChagas' disease, caused by the protozoan Trypanosoma cruzi, represents a serious healt... more SUMMARYChagas' disease, caused by the protozoan Trypanosoma cruzi, represents a serious health problem in Latin America, and the available chemotherapy, which is based on 2 nitro-derivatives, is not satisfactory. In folk medicine, natural products including naphthoquinones have been employed for the treatment of different parasitic diseases. In the pursuit of alternative drugs for Chagas' disease, we investigated the mechanism of action of the triazolic naphthoquinone (TN; 2,2-dimethyl-3-(4-phenyl-1H-1,2,3-triazol-1-yl)-2,3-dihydronaphtho[1,2-b]furan-4,5-dione), which is the most active compound against T. cruzi trypomastigotes among a series of naphthofuranquinones. TN was active against the 3 parasite forms producing a dose-dependent inhibitory effect. In epimastigotes, TN induced reservosome disruption, flagellar blebbing, Golgi disorganization, the presence of cytosolic concentric membrane structures and abnormal multiflagellar parasites. The treatment also led to the ap...
Medicinal Chemistry, 2007
This study describes the design, synthesis and trypanocidal evaluation of new azaheterocyclic der... more This study describes the design, synthesis and trypanocidal evaluation of new azaheterocyclic derivatives (4-8). These compounds were designed as megazol (1) analogs based on bioisosterism tools and were synthesized to investigate the possible pharmacophoric contribution of the 1,2,4-triazole nucleus, the position of the heterocyclic nucleus and presence of the nitro group, to the activity against the bloodstream trypomastigote forms of Trypanosoma cruzi. The most potent compound was 6, a nitro derivative obtained by substitution of a thiadiazole by a triazole ring and by moving the nitro group from C-5 position, as in 1, to the C-4 position. Finally, we have used semi-empirical theoretical calculations to discuss the correlation of some stereo electronic properties with biological activity in an attempt to understand the possible mechanism of action of the designed series of compounds.
Journal of Proteomics, 2010
Chagas' disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America, which cu... more Chagas' disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America, which current treatment presents variable efficacy and serious side effects. A previous screening of naphthoquinone derivatives pointed to the naphthoimidazoles N1, N2 and N3 as the most active compounds against T. cruzi. In this study, a proteomic approach was employed to identify proteins involved in the N1, N2 and N3 trypanocidal activity. In epimastigotes, the naphthoimidazoles are involved in multiple mechanisms: (a) redox metabolism; (b) energy production; (c) ergosterol biosynthesis; (d) cytoskeleton assembly; (e) protein metabolism and biosynthesis; and (f) chaperones modulation. They induce an imbalance in crucial pathways of the parasite, leading to the loss of metabolic homeostasis and T. cruzi death.
Journal of Antimicrobial Chemotherapy, 2005
Investigation of the mode of action of the naphthoimidazole N1, obtained from the reaction of b-l... more Investigation of the mode of action of the naphthoimidazole N1, obtained from the reaction of b-lapachone with benzaldehyde, which among 45 semi-synthetic derivatives of naphthoquinones isolated from Tabebuia sp. was one of the most active compounds against Trypanosoma cruzi trypomastigotes. Methods: Quantification of the effect of N1 against the proliferative forms of T. cruzi, and investigation of potential targets in the parasite using electron microscopy and flow cytometry techniques. Results: N1 presented the following order of activity: amastigotes > trypomastigotes > epimastigotes. The effect on intracellular forms was 25 times higher than on macrophages and heart muscle cells. N1-treated parasites presented an abnormal chromatin condensation and mitochondrial damage. In epimastigotes, alterations of reservosomes were observed, and in trypomastigotes, a decrease in the electron density of acidocalcisomes was observed. In epimastigotes, the naphthoimidazole inhibited the activity of succinate cytochrome c reductase. Labelling with rhodamine 123 or Acridine Orange was decreased in both forms treated with N1. Conclusions: The results suggest that epimastigotes, reservosomes, mitochondrion, and nucleus contain N1 targets. In trypomastigotes, in which reservosomes are absent, the organelles affected by the compound were also the mitochondrion and nucleus, as well as acidocalcisomes, in which the decrease in electron density could be due to the use of polyphosphate as an alternative energy supply.
Free Radical Biology and Medicine, 2009
Despite ongoing efforts, the current treatment for Chagas disease is still unsatisfactory, mainly... more Despite ongoing efforts, the current treatment for Chagas disease is still unsatisfactory, mainly because of the severe side effects and variable efficacy of the available nitroheterocycles. Our group has been assaying natural quinones isolated from Brazilian flora, and their derivatives, as alternative chemotherapeutic agents against Trypanosoma cruzi. From C-allyl lawsone three naphthofuranquinones were synthesized, which were active against trypomastigotes and epimastigotes. Here, we further investigated the activity and the mechanisms of action of these quinones. They exhibited powerful effects on intracellular amastigotes, presenting low toxicity to the host cells. Ultrastructural analyses of treated epimastigotes and trypomastigotes indicated a potent effect of the three naphthofuranquinones on the parasite mitochondrion, which appeared drastically swollen and with a washed-out matrix profile. Fluorescence-activated cell sorting analysis of rhodamine 123-stained T. cruzi showed that the three naphthofuranquinones caused a potent dose-dependent collapse of the mitochondrial membrane potential, especially in the epimastigote form. Naphthofuranquinones also decreased specifically mitochondrial complex I-III activity in both epimastigotes and trypomastigotes, parallel to a reduction in succinate-induced oxygen consumption. Mitochondrial hydrogen peroxide formation was also increased in epimastigotes after treatment with the naphthofuranquinones. Our results indicate that the trypanocidal action of the naphthofuranquinones is associated with mitochondrial dysfunction, leading to increased reactive oxygen species generation and parasite death.
European Journal of Medicinal Chemistry, 2008
[1,2,3]-Triazole derivatives of nor-b-lapachone were synthesized and assayed against the infectiv... more [1,2,3]-Triazole derivatives of nor-b-lapachone were synthesized and assayed against the infective bloodstream trypomastigote form of Trypanosoma cruzi, the etiological agent of Chagas disease. All the derivatives were more active than the original quinones, with IC 50 /1 day values in the range of 17 to 359 mM, the apolar phenyl substituted triazole 6 being the most active compound. These triazole derivatives of nor-b-lapachone emerge as interesting new lead compounds in drug development for Chagas disease.
European Journal of Medicinal Chemistry, 2004
We synthesized new naphthoimidazoles from b-lapachone with an aromatic moiety linked to the imida... more We synthesized new naphthoimidazoles from b-lapachone with an aromatic moiety linked to the imidazole ring, using phenylic and heterocyclic aldehydes. The most active compound against Trypanosoma cruzi had a p-methyl group linked to the phenyl ring, presenting an EC 50 value of 15.5 ± 2.9 µM. No reliable correlation could be established with the biological activity and the structure of in the phenylic series. For the heterocyclic series, activity was associated with a three bond-distance from nitrogen to the imidazole ring, in accordance with our previous work.
European Journal of Medicinal Chemistry, 2004
We synthesized new naphthoimidazoles from b-lapachone with an aromatic moiety linked to the imida... more We synthesized new naphthoimidazoles from b-lapachone with an aromatic moiety linked to the imidazole ring, using phenylic and heterocyclic aldehydes. The most active compound against Trypanosoma cruzi had a p-methyl group linked to the phenyl ring, presenting an EC 50 value of 15.5 ± 2.9 µM. No reliable correlation could be established with the biological activity and the structure of in the phenylic series. For the heterocyclic series, activity was associated with a three bond-distance from nitrogen to the imidazole ring, in accordance with our previous work.
Chemico-Biological Interactions, 2009
In order to elucidate the effect on mammal systems of new derivatives from 2-hydroxy-3-allylnapht... more In order to elucidate the effect on mammal systems of new derivatives from 2-hydroxy-3-allylnaphthoquinone, ␣-iodinated naphthofuranquinone (NPPN-3223), -iodinated naphthofuranquinone (NPPN-3222) and -methyl naphthofuranquinone (NPPN-3226) synthesized as possible trypanocidal agents, their effect on rat liver microsomal lipid peroxidation was investigated. They (a) inhibited NADPH-dependent, iron-catalyzed microsomal rat liver lipid peroxidation; (b) did not inhibit the tertbutyl hydroperoxide-dependent lipid peroxidation; (c) did not inhibit ascorbate-lipid peroxidation with the exception of NPPN-3226 which did inhibit it; (d) stimulated NADPH oxidation and microsomal oxygen uptake; (e) increased superoxide anion formation by NADPH-supplemented microsomes and (f) stimulated ascorbate oxidation. The three drugs were reduced to their seminaphthofuranquinone radical by the liver NADPH-P450 reductase system, as detected by ESR measurements. These results support the hypothesis that naphthofuranquinones reduction by microsomal NADPH-P450 reductase and semiquinone oxidation by molecular oxygen diverts electrons, preventing microsomal lipid peroxidation. In addition, hydroquinones and/or semiquinones formed by naphthofuranquinones reduction would be capable of lipid peroxidation inhibition and on interacting with the lipid peroxide radicals can lead to an antioxidant effect as we suggested for NPPN-3226 in close agreement to the inhibition of ascorbate-lipid peroxidation. Due to the properties of these molecules and their incoming structure developments, naphthofuranquinones would be considered as potentially promising therapeutic agents, mainly against Chagas disease.
Bioorganic & Medicinal Chemistry, 2008
We report herein a straightforward and efficient one-step reaction to prepare new nor-b-lapachone... more We report herein a straightforward and efficient one-step reaction to prepare new nor-b-lapachone derivatives tethered with phenylthio groups at position 3 of the furan ring. We have screened the compounds on bloodstream trypomastigotes of Trypanosoma cruzi, the causative agent of Chagas disease, aimed at finding a new prototype with high trypanocidal activity. The new compounds possess a broad range of activity (IC 50 /24 h from 9.2 to 182.7 lM), higher than the original quinone (391.5 lM) and four of them higher than standard drug benznidazole (103.6 lM). The most active was compound 13b (9.2 lM), being 11 times active than benznidazole and the less toxic derivative to heart muscle cells.