RESUMO
The COVID-19 pandemic is the third outbreak this century of a zoonotic disease caused by a coronavirus, following the emergence of severe acute respiratory syndrome (SARS) in 20031 and Middle East respiratory syndrome (MERS) in 20122. Treatment options for coronaviruses are limited. Here we show that clofazimine-an anti-leprosy drug with a favourable safety profile3-possesses inhibitory activity against several coronaviruses, and can antagonize the replication of SARS-CoV-2 and MERS-CoV in a range of in vitro systems. We found that this molecule, which has been approved by the US Food and Drug Administration, inhibits cell fusion mediated by the viral spike glycoprotein, as well as activity of the viral helicase. Prophylactic or therapeutic administration of clofazimine in a hamster model of SARS-CoV-2 pathogenesis led to reduced viral loads in the lung and viral shedding in faeces, and also alleviated the inflammation associated with viral infection. Combinations of clofazimine and remdesivir exhibited antiviral synergy in vitro and in vivo, and restricted viral shedding from the upper respiratory tract. Clofazimine, which is orally bioavailable and comparatively cheap to manufacture, is an attractive clinical candidate for the treatment of outpatients and-when combined with remdesivir-in therapy for hospitalized patients with COVID-19, particularly in contexts in which costs are an important factor or specialized medical facilities are limited. Our data provide evidence that clofazimine may have a role in the control of the current pandemic of COVID-19 and-possibly more importantly-in dealing with coronavirus diseases that may emerge in the future.
Assuntos
Antivirais/farmacologia , Clofazimina/farmacologia , Coronavirus/classificação , Coronavirus/efeitos dos fármacos , SARS-CoV-2/efeitos dos fármacos , Monofosfato de Adenosina/análogos & derivados , Monofosfato de Adenosina/farmacologia , Monofosfato de Adenosina/uso terapêutico , Alanina/análogos & derivados , Alanina/farmacologia , Alanina/uso terapêutico , Animais , Anti-Inflamatórios/farmacocinética , Anti-Inflamatórios/farmacologia , Anti-Inflamatórios/uso terapêutico , Antivirais/farmacocinética , Antivirais/uso terapêutico , Disponibilidade Biológica , Fusão Celular , Linhagem Celular , Clofazimina/farmacocinética , Clofazimina/uso terapêutico , Coronavirus/crescimento & desenvolvimento , Coronavirus/patogenicidade , Cricetinae , DNA Helicases/antagonistas & inibidores , Sinergismo Farmacológico , Feminino , Humanos , Estágios do Ciclo de Vida/efeitos dos fármacos , Masculino , Mesocricetus , Profilaxia Pré-Exposição , SARS-CoV-2/crescimento & desenvolvimento , Especificidade da Espécie , Glicoproteína da Espícula de Coronavírus/antagonistas & inibidores , Transcrição Gênica/efeitos dos fármacos , Transcrição Gênica/genéticaRESUMO
The apicomplexan parasite Cryptosporidium is a leading cause of childhood diarrhea in developing countries. Current treatment options are inadequate and multiple preclinical compounds are being actively pursued as potential drugs for cryptosporidiosis. Unlike most apicomplexans, Cryptosporidium spp. sequentially replicate asexually and then sexually within a single host to complete their lifecycles. Anti-cryptosporidial compounds are generally identified or tested through in vitro phenotypic assays that only assess the asexual stages. Therefore, compounds that specifically target the sexual stages remain unexplored. In this study, we leveraged the ReFRAME drug repurposing library against a newly devised multi-readout imaging assay to identify small-molecule compounds that modulate macrogamont differentiation and maturation. RNA-seq studies confirmed selective modulation of macrogamont differentiation for 10 identified compounds (9 inhibitors and 1 accelerator). The collective transcriptomic profiles of these compounds indicates that translational repression accompanies Cryptosporidium sexual differentiation, which we validated experimentally. Additionally, cross comparison of the RNA-seq data with promoter sequence analysis for stage-specific genes converged on a key role for an Apetala 2 (AP2) transcription factor (cgd2_3490) in differentiation into macrogamonts. Finally, drug annotation for the ReFRAME hits indicates that an elevated supply of energy equivalence in the host cell is critical for macrogamont formation.
Assuntos
Criptosporidiose , Cryptosporidium , Estágios do Ciclo de Vida , Proteínas de Protozoários , Criptosporidiose/parasitologia , Criptosporidiose/tratamento farmacológico , Proteínas de Protozoários/metabolismo , Proteínas de Protozoários/genética , Estágios do Ciclo de Vida/efeitos dos fármacos , Cryptosporidium/efeitos dos fármacos , Cryptosporidium/genética , Cryptosporidium/metabolismo , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Animais , Humanos , Bibliotecas de Moléculas Pequenas/farmacologiaRESUMO
Malaria is a devastating infectious disease, which causes over 400,000 deaths per annum and impacts the lives of nearly half the world's population. The causative agent, a protozoan parasite, replicates within red blood cells (RBCs), eventually destroying the cells in a lytic process called egress to release a new generation of parasites. These invade fresh RBCs to repeat the cycle. Egress is regulated by an essential parasite subtilisin-like serine protease called SUB1. Here, we describe the development and optimization of substrate-based peptidic boronic acids that inhibit Plasmodium falciparum SUB1 with low nanomolar potency. Structural optimization generated membrane-permeable, slow off-rate inhibitors that prevent Pfalciparum egress through direct inhibition of SUB1 activity and block parasite replication in vitro at submicromolar concentrations. Our results validate SUB1 as a potential target for a new class of antimalarial drugs designed to prevent parasite replication and disease progression.
Assuntos
Antimaláricos/farmacologia , Ácidos Borônicos/farmacologia , Peptídeos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Proteínas de Protozoários/química , Subtilisinas/química , Antimaláricos/síntese química , Sítios de Ligação , Ácidos Borônicos/síntese química , Desenho de Fármacos , Eritrócitos/efeitos dos fármacos , Eritrócitos/parasitologia , Expressão Gênica , Humanos , Cinética , Estágios do Ciclo de Vida/efeitos dos fármacos , Estágios do Ciclo de Vida/fisiologia , Modelos Moleculares , Simulação de Acoplamento Molecular , Peptídeos/síntese química , Plasmodium falciparum/enzimologia , Plasmodium falciparum/genética , Plasmodium falciparum/crescimento & desenvolvimento , Ligação Proteica , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Relação Estrutura-Atividade , Especificidade por Substrato , Subtilisinas/antagonistas & inibidores , Subtilisinas/genética , Subtilisinas/metabolismo , TermodinâmicaRESUMO
The neonicotinoid insecticide thiamethoxam (TMX) is widely used to protect crops against insect pests. Despite some desirable properties such as its low toxicity to birds and mammals, concerns have been raised about its toxicity to non-target arthropods, including freshwater insects like chironomids. Whereas multiple studies have investigated chronic effects of neonicotinoids in chironomid larvae at standardized laboratory conditions, a better understanding of their chronic toxicity under variable temperatures and exposure is needed for coherent extrapolation from the laboratory to the field. Here, we developed a quantitative mechanistic effect model for Chironomus riparius, to simulate the species' life history under dynamic temperatures and exposure concentrations of TMX. Laboratory experiments at four different temperatures (12, 15, 20, 23 °C) and TMX concentrations between 4 and 51⯵g/L were used to calibrate the model. Observed concentration-dependent effects of TMX in C. riparius included slower growth, later emergence, and higher mortality rates with increasing concentrations. Furthermore, besides a typical accelerating effect on the organisms' growth and development, higher temperatures further increased the effects associated with TMX. With some data-informed modeling decisions, most prominently the inclusion of a size dependence that makes larger animals more sensitive to TMX, the model was parametrized to convincingly reproduce the data. Experiments at both a constant (20 °C) and a dynamically increasing temperature (15-23 °C) with pulsed exposure were used to validate the model. Finally, the model was used to simulate realistic exposure conditions using two reference exposure scenarios measured in Missouri and Nebraska, utilizing a moving time window (MTW) and either a constant temperature (20 °C) or the measured temperature profiles belonging to each respective scenario. Minimum exposure multiplication factors leading to a 10% effect (EP10) in the survival at pupation, i.e., the most sensitive endpoint found in this study, were 25.67 and 21.87 for the Missouri scenario and 38.58 and 44.64 for the Nebraska scenario, when using the respective temperature assumptions. While the results illustrate that the use of real temperature scenarios does not systematically modify the EPx in the same direction (making it either more or less conservative when used as a risk indicator), the advantage of this approach is that it increases the realism and thus reduces the uncertainty associated with the model predictions.
Assuntos
Chironomidae , Inseticidas , Larva , Temperatura , Tiametoxam , Animais , Tiametoxam/toxicidade , Chironomidae/efeitos dos fármacos , Inseticidas/toxicidade , Larva/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Estágios do Ciclo de Vida/efeitos dos fármacos , Neonicotinoides/toxicidadeRESUMO
The Plasmodium falciparum mitochondrial electron transport chain (mETC) is responsible for essential metabolic pathways such as de novo pyrimidine synthesis and ATP synthesis. The mETC complex III (cytochrome bc1 complex) is responsible for transferring electrons from ubiquinol to cytochrome c and generating a proton gradient across the inner mitochondrial membrane, which is necessary for the function of ATP synthase. Recent studies have revealed that the composition of Plasmodium falciparum complex III (PfCIII) is divergent from humans, highlighting its suitability as a target for specific inhibition. Indeed, PfCIII is the target of the clinically used anti-malarial atovaquone and of several inhibitors undergoing pre-clinical trials, yet its role in parasite biology has not been thoroughly studied. We provide evidence that the universally conserved subunit, PfRieske, and the new parasite subunit, PfC3AP2, are part of PfCIII, with the latter providing support for the prediction of its divergent composition. Using inducible depletion, we show that PfRieske, and therefore, PfCIII as a whole, is essential for asexual blood stage parasite survival, in line with previous observations. We further found that depletion of PfRieske results in gametocyte maturation defects. These phenotypes are linked to defects in mitochondrial functions upon PfRieske depletion, including increased sensitivity to mETC inhibitors in asexual stages and decreased cristae abundance alongside abnormal mitochondrial morphology in gametocytes. This is the first study that explores the direct role of the PfCIII in gametogenesis via genetic disruption, paving the way for a better understanding of the role of mETC in the complex life cycle of these important parasites and providing further support for the focus of antimalarial drug development on this pathway.
Assuntos
Antimaláricos , Atovaquona , Complexo III da Cadeia de Transporte de Elétrons , Malária Falciparum , Mitocôndrias , Plasmodium falciparum , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/metabolismo , Plasmodium falciparum/genética , Atovaquona/farmacologia , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Complexo III da Cadeia de Transporte de Elétrons/genética , Complexo III da Cadeia de Transporte de Elétrons/antagonistas & inibidores , Antimaláricos/farmacologia , Mitocôndrias/metabolismo , Mitocôndrias/efeitos dos fármacos , Malária Falciparum/parasitologia , Malária Falciparum/tratamento farmacológico , Humanos , Proteínas de Protozoários/metabolismo , Proteínas de Protozoários/genética , Proteínas de Protozoários/antagonistas & inibidores , Estágios do Ciclo de Vida/efeitos dos fármacosRESUMO
Malaria, caused by infection with Plasmodium parasites, remains a significant global health concern. For decades, genetic intractability and limited tools hindered our ability to study essential proteins and pathways in Plasmodium falciparum, the parasite associated with the most severe malaria cases. However, recent years have seen major leaps forward in the ability to genetically manipulate P. falciparum parasites and conditionally control protein expression/function. The conditional knockdown systems used in P. falciparum target all 3 components of the central dogma, allowing researchers to conditionally control gene expression, translation, and protein function. Here, we review some of the common knockdown systems that have been adapted or developed for use in P. falciparum. Much of the work done using conditional knockdown approaches has been performed in asexual, blood-stage parasites, but we also highlight their uses in other parts of the life cycle and discuss new ways of applying these systems outside of the intraerythrocytic stages. With the use of these tools, the field's understanding of parasite biology is ever increasing, and promising new pathways for antimalarial drug development are being discovered.
Assuntos
Antimaláricos/farmacologia , Eritrócitos/efeitos dos fármacos , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Animais , Eritrócitos/parasitologia , Humanos , Estágios do Ciclo de Vida/efeitos dos fármacos , Estágios do Ciclo de Vida/genética , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/genética , Proteínas de Protozoários/efeitos dos fármacos , Proteínas de Protozoários/metabolismoRESUMO
Antimalarial drugs have thus far been chiefly derived from two sources-natural products and synthetic drug-like compounds. Here we investigate whether antimalarial agents with novel mechanisms of action could be discovered using a diverse collection of synthetic compounds that have three-dimensional features reminiscent of natural products and are underrepresented in typical screening collections. We report the identification of such compounds with both previously reported and undescribed mechanisms of action, including a series of bicyclic azetidines that inhibit a new antimalarial target, phenylalanyl-tRNA synthetase. These molecules are curative in mice at a single, low dose and show activity against all parasite life stages in multiple in vivo efficacy models. Our findings identify bicyclic azetidines with the potential to both cure and prevent transmission of the disease as well as protect at-risk populations with a single oral dose, highlighting the strength of diversity-oriented synthesis in revealing promising therapeutic targets.
Assuntos
Antimaláricos/síntese química , Antimaláricos/farmacologia , Azetidinas/uso terapêutico , Descoberta de Drogas , Estágios do Ciclo de Vida/efeitos dos fármacos , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/crescimento & desenvolvimento , Animais , Antimaláricos/administração & dosagem , Antimaláricos/uso terapêutico , Compostos Azabicíclicos/administração & dosagem , Compostos Azabicíclicos/síntese química , Compostos Azabicíclicos/farmacologia , Compostos Azabicíclicos/uso terapêutico , Azetidinas/administração & dosagem , Azetidinas/efeitos adversos , Azetidinas/farmacologia , Citosol/enzimologia , Modelos Animais de Doenças , Feminino , Fígado/efeitos dos fármacos , Fígado/parasitologia , Macaca mulatta/parasitologia , Malária Falciparum/prevenção & controle , Malária Falciparum/transmissão , Masculino , Camundongos , Fenilalanina-tRNA Ligase/antagonistas & inibidores , Compostos de Fenilureia/administração & dosagem , Compostos de Fenilureia/síntese química , Compostos de Fenilureia/farmacologia , Compostos de Fenilureia/uso terapêutico , Plasmodium falciparum/citologia , Plasmodium falciparum/enzimologia , SegurançaRESUMO
Conventional therapy of visceral leishmaniasis (VL) remains challenging with the pitfall of toxicity, drug resistance, and expensive. Hence, urgent need for an alternative approach is essential. In this study, we evaluated the potential of combination therapy with eugenol oleate and miltefosine in Leishmania donovani infected macrophages and in the BALB/c mouse model. The interactions between eugenol oleate and miltefosine were found to be additive against promastigotes and amastigotes with xΣFIC 1.13 and 0.68, respectively. Significantly (p < 0.001) decreased arginase activity, increased nitrite generation, improved pro-inflammatory cytokines, and phosphorylated p38MAPK were observed after combination therapy with eugenol oleate and miltefosine. >80% parasite clearance in splenic and hepatic tissue with concomitant nitrite generation, and anti-VL cytokines productions were observed after orally administered miltefosine (5 mg/kg body weight) and eugenol oleate (15 mg/kg body weight) in L. donovani-infected BALB/c mice. Altogether, this study suggested the possibility of an oral combination of miltefosine with eugenol oleate against visceral leishmaniasis.
Assuntos
Citocinas/metabolismo , Eugenol/uso terapêutico , Imunidade , Leishmaniose Visceral/tratamento farmacológico , Leishmaniose Visceral/imunologia , Óxido Nítrico/biossíntese , Fosforilcolina/análogos & derivados , Administração Oral , Animais , Morte Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Citocinas/biossíntese , Interações Medicamentosas , Quimioterapia Combinada , Eugenol/administração & dosagem , Eugenol/farmacologia , Feminino , Imunidade/efeitos dos fármacos , Concentração Inibidora 50 , Leishmania donovani/efeitos dos fármacos , Leishmania donovani/crescimento & desenvolvimento , Leishmania donovani/imunologia , Leishmania donovani/ultraestrutura , Leishmaniose Visceral/parasitologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Macrófagos/imunologia , Macrófagos/parasitologia , Macrófagos/ultraestrutura , Masculino , Camundongos Endogâmicos BALB C , Óxido Nítrico Sintase Tipo II/metabolismo , Parasitos/efeitos dos fármacos , Parasitos/crescimento & desenvolvimento , Parasitos/imunologia , Parasitos/ultraestrutura , Fosforilação/efeitos dos fármacos , Fosforilcolina/administração & dosagem , Fosforilcolina/farmacologia , Fosforilcolina/uso terapêutico , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
Half of the world's population lives in countries at risk of malaria infection, which results in approximately 450,000 deaths annually. Malaria parasites infect erythrocytes in a coordinated manner, with cycle durations in multiples of 24 hours, which reflects a behavior consistent with the host's circadian cycle. Interference in cycle coordination can help the immune system to naturally fight infection. Consequently, there is a search for new drugs that interfere with the cycle duration for combined treatment with conventional antimalarials. Melatonin appears to be a key host hormone responsible for regulating circadian behavior in the parasite cycle. In addition to host factors, there are still unknown factors intrinsic to the parasite that control the cycle duration. In this review, we present a series of reports of indole compounds and melatonin derivatives with antimalarial activity that were tested on several species of Plasmodium to evaluate the cytotoxicity to parasites and human cells, in addition to the ability to interfere with the development of the erythrocytic cycle. Most of the reported compounds had an IC50 value in the low micromolar range, without any toxicity to human cells. Triptosil, an indole derivative of melatonin, was able to inhibit the effect of melatonin in vitro without causing changes to the parasitemia. The wide variety of tested compounds indicates that it is possible to develop a compound capable of safely eliminating parasites from the host and interfering with the life cycle, which is promising for the development of new combined therapies against malaria.
Assuntos
Antimaláricos/farmacologia , Descoberta de Drogas , Estágios do Ciclo de Vida/efeitos dos fármacos , Malária Falciparum/tratamento farmacológico , Melatonina/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Animais , Resistência a Múltiplos Medicamentos , Interações Hospedeiro-Patógeno , Humanos , Malária Falciparum/parasitologia , Melatonina/análogos & derivados , Plasmodium falciparum/crescimento & desenvolvimentoRESUMO
Chagas disease (ChD), caused by Trypanosoma cruzi, remains a challenge for the medical and scientific fields due to the inefficiency of the therapeutic approaches available for its treatment. Thiosemicarbazones and hydrazones present a wide spectrum of bioactivities and are considered a platform for the design of new anti-T. cruzi drug candidates. Herein, the potential antichagasic activities of [(E)-2-(1-(4-chlorophenylthio)propan-2-ylidene)-hydrazinecarbothioamides] (C1, C3), [(E)-N'-(1-((4-chlorophenyl)thio)propan-2-ylidene)benzohydrazide] (C2), [(E)-2-(1-(4-, and [(E)-2-(1-((4-chlorophenyl)thio)propan-2-ylidene)hydrazinecarboxamide] (C4) were investigated. Macrophages (MOs) from C57BL/6 mice stimulated with C1 and C3, but not with C2 and C4, reduced amastigote replication and trypomastigote release, independent of nitric oxide (NO) and reactive oxygen species production and indoleamine 2,3-dioxygenase activity. C3, but not C1, reduced parasite uptake by MOs and potentiated TNF production. In cardiomyocytes, C3 reduced trypomastigote release independently of NO, TNF, and IL-6 production. C1 and C3 were non-toxic to the host cells. A reduction of parasite release was found during infection of MOs with trypomastigotes pre-incubated with C1 or C3 and MOs pre-stimulated with compounds before infection. Moreover, C1 and C3 acted directly on trypomastigotes, killing them faster than Benznidazole, and inhibited T. cruzi proliferation at various stages of its intracellular cycle. Mechanistically, C1 and C3 inhibit parasite duplication, and this process cannot be reversed by inhibiting the DNA damage response. In vivo, C1 and C3 attenuated parasitemia in T. cruzi-infected mice. Moreover, C3 loaded in a lipid nanocarrier system (nanoemulsion) maintained anti-T. cruzi activity in vivo. Collectively, these data suggest that C1 and C3 are candidates for the treatment of ChD and present activity in both the host and parasite cells.
Assuntos
Tiossemicarbazonas/química , Tripanossomicidas/química , Animais , Sobrevivência Celular/efeitos dos fármacos , Doença de Chagas/tratamento farmacológico , Doença de Chagas/parasitologia , Doença de Chagas/patologia , Cisteína Endopeptidases/metabolismo , Citocinas/metabolismo , Modelos Animais de Doenças , Desenho de Fármacos , Feminino , Estágios do Ciclo de Vida/efeitos dos fármacos , Macrófagos/citologia , Macrófagos/metabolismo , Macrófagos/parasitologia , Camundongos , Camundongos Endogâmicos C57BL , Conformação Molecular , Óxido Nítrico/metabolismo , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/metabolismo , Ratos , Tiossemicarbazonas/farmacologia , Tiossemicarbazonas/uso terapêutico , Tripanossomicidas/farmacologia , Tripanossomicidas/uso terapêutico , Trypanosoma cruzi/efeitos dos fármacos , Trypanosoma cruzi/fisiologiaRESUMO
There is an urgent need for new drugs to treat malaria, with broad therapeutic potential and novel modes of action, to widen the scope of treatment and to overcome emerging drug resistance. Here we describe the discovery of DDD107498, a compound with a potent and novel spectrum of antimalarial activity against multiple life-cycle stages of the Plasmodium parasite, with good pharmacokinetic properties and an acceptable safety profile. DDD107498 demonstrates potential to address a variety of clinical needs, including single-dose treatment, transmission blocking and chemoprotection. DDD107498 was developed from a screening programme against blood-stage malaria parasites; its molecular target has been identified as translation elongation factor 2 (eEF2), which is responsible for the GTP-dependent translocation of the ribosome along messenger RNA, and is essential for protein synthesis. This discovery of eEF2 as a viable antimalarial drug target opens up new possibilities for drug discovery.
Assuntos
Antimaláricos/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Malária/parasitologia , Plasmodium/efeitos dos fármacos , Plasmodium/metabolismo , Biossíntese de Proteínas/efeitos dos fármacos , Quinolinas/farmacologia , Animais , Antimaláricos/administração & dosagem , Antimaláricos/efeitos adversos , Antimaláricos/farmacocinética , Descoberta de Drogas , Feminino , Estágios do Ciclo de Vida/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/parasitologia , Malária/tratamento farmacológico , Masculino , Modelos Moleculares , Fator 2 de Elongação de Peptídeos/antagonistas & inibidores , Fator 2 de Elongação de Peptídeos/metabolismo , Plasmodium/genética , Plasmodium/crescimento & desenvolvimento , Plasmodium berghei/efeitos dos fármacos , Plasmodium berghei/fisiologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/metabolismo , Plasmodium vivax/efeitos dos fármacos , Plasmodium vivax/metabolismo , Quinolinas/administração & dosagem , Quinolinas/química , Quinolinas/farmacocinéticaRESUMO
Trichogramma pretiosum is one of the main egg parasitoids used in the control of lepidopteran pests in Brazil. This natural enemy can be negatively affected by the use of insecticides, herbicides, and fungicides. The present work used a systematic review and meta-analysis to group information from multiple studies on the selectivity of pesticides (279 commercial products) in rice, corn, soybean, apple and peach crops for immature stages (egg-larva, pre-pupa, and pupa) and adult parasitoids. The selected studies used the International Organization for Biological and Integrated Control (IOBC) methodology with the same adaptations for T. pretiosum. The meta-analysis found that corn crops had the highest frequency of tests (2 0 7). The most frequently tested active ingredients (a.i.) were glyphosate, glyphosate isopropylamine salt, and sulfur at frequencies of 41, 32 and 24 tests, respectively. The pesticides registered for rice crops showed the greatest sublethal effects on T. pretiosum, with an approximately 47% reduction in parasitism (RP) or emergence (RE). The adult stage of the parasitoid showed greater sensitivity to the tested pesticides (65% RP), in comparison to the immature stages. In general, insecticides showed superior toxicity for all development stages of T. pretiosum, compared to herbicides and fungicides, regardless of the recommended dosage for the crop. The present study aggregates information related to selectivity for the four life stages of T. pretiosum, contributing significantly to the integration of biological control and chemical control in rice, corn, soybean, apple and peach crops in Brazil.
Assuntos
Resistência a Medicamentos/fisiologia , Himenópteros/fisiologia , Controle Biológico de Vetores , Praguicidas/farmacologia , Animais , Brasil , Produtos Agrícolas/parasitologia , Himenópteros/crescimento & desenvolvimento , Estágios do Ciclo de Vida/efeitos dos fármacos , Doenças das Plantas/parasitologia , Doenças das Plantas/prevenção & controleRESUMO
Hazardous substances, such as microcystin-LR (MC-LR) and phenanthrene (Phe) are ubiquitous co-contaminants in eutrophic freshwaters, which cause harms to aquatic organisms. However, the risks associated with the co-exposure of aquatic biota to these two chemicals in the environment have received little attention. In this study, the single and mixture toxic effects of MC-LR and Phe mixtures were investigated in Daphnia magna after acute and chronic exposure. Acute tests showed that the median effective concentrations (48 h) for MC-LR, Phe and their mixtures were 13.46, 0.57 and 8.84 mg/L, respectively. Mixture toxicity prediction results indicated that the independent action model was more applicable than the concentration addition model. Moreover, combination index method suggested that the mixture toxicity was concentration dependent. Synergism was elicited at low concentrations of MC-LR and Phe exposure (≤4.04 + 0.17 mg/L), whereas antagonistic or additive effects were induced at higher concentrations. The involved mechanism of antagonism was presumably attributable to the protective effects of detoxification genes activated by high concentrations of MC-LR in mixtures. Additionally, chronic results also showed that exposure to a MC-LR and Phe mixture at low concentrations (≤50 +2 µg/L) resulted in greater toxic effects on D. magna life history than either chemical acting alone. The significant inhibition on detoxification genes and increased accumulation of MC-LR could be accounted for their synergistic toxic effects on D. magna. Our findings revealed the exacerbated ecological hazard of MC-LR and Phe at environmental concentrations (≤50 +2 µg/L), and provided new insights to the potential toxic mechanisms of MC-LR and Phe in aquatic animals.
Assuntos
Daphnia/efeitos dos fármacos , Toxinas Marinhas/toxicidade , Microcistinas/toxicidade , Fenantrenos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Organismos Aquáticos/efeitos dos fármacos , Daphnia/genética , Daphnia/crescimento & desenvolvimento , Daphnia/metabolismo , Interações Medicamentosas , Água Doce/química , Inativação Metabólica/efeitos dos fármacos , Inativação Metabólica/genética , Estágios do Ciclo de Vida/efeitos dos fármacos , Toxinas Marinhas/análise , Microcistinas/análise , Fenantrenos/análiseRESUMO
Coccinella septempunctata (ladybird) is one of the foremost natural predators that feed on aphids. Thus, C. septempunctata serves as an effective biological control agent in integrated pest management (IPM) programs. To supplement the activity of biological control agents, IPM programs often incorporate chemical pesticides to bolster crop protection. To evaluate the effects of a potent insecticide, tolfenpyrad, on C. septempunctata, we tested the sublethal effects of tolfenpyrad on all developmental stages of the life cycle of C. septempunctata and its effects on the next generation. For sublethal testing of the parent generation, the LR50 of tolfenpyrad for C. septempunctata was determined to range from 1.04 to 8.43 g a.i. /hm2 within a set exposure period, while the hazard quotient (HQ) values were above our threshold value of 2 during the entire observation period. These data indicated a potential toxicity risk from tolfenpyrad exposure. The no observed effect application rates (NOERs) of tolfenpyrad on parents (F0) were determined for survival (0.485 g a.i. /hm2), developmental time of pupation (0.242 g a.i. /hm2), and fecundity (0.485 g a.i. /hm2). Application of sublethal doses to unexposed progeny (F1) of exposed parents, prolonged the L1 (1st instar of larvae) and L2 (2nd instar of larvae) stage, while the total longevity, intrinsic rate of increase (r), finite rate of increase (γ), net reproductive rate (R0), and mean generation time (T) were significantly reduced. These results demonstrated the negative influence of sublethal concentrations of tolfenpyrad on C. septempunctata and its persistent effects on subsequent generations.
Assuntos
Besouros/efeitos dos fármacos , Inseticidas/toxicidade , Pirazóis/toxicidade , Animais , Besouros/fisiologia , Feminino , Fertilidade/efeitos dos fármacos , Larva/efeitos dos fármacos , Larva/fisiologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Masculino , Controle de Pragas , Reprodução/efeitos dos fármacosRESUMO
Microplastics are ubiquitous in aquatic ecosystems, but little information is currently available on the dangers and risks to living organisms. In order to assess the ecotoxicity of environmental microplastics (MPs), samples were collected from the beaches of two islands in the Guadeloupe archipelago, Petit-Bourg (PB) located on the main island of Guadeloupe and Marie-Galante (MG) on the second island of the archipelago. These samples have a similar polymer composition with mainly polyethylene (PE) and polypropylene (PP). However, these two samples are very dissimilar with regard to their contamination profile and their toxicity. MPs from MG contain more lead, cadmium and organochlorine compounds while those from PB have higher levels of copper, zinc and hydrocarbons. The leachates of these two samples of MPs induced sublethal effects on the growth of sea urchins and on the pulsation frequency of jellyfish ephyrae but not on the development of zebrafish embryos. The toxic effects are much more marked for samples from the PB site than those from the MG site. This work demonstrates that MPs can contain high levels of potentially bioavailable toxic substances that may represent a significant ecotoxicological risk, particularly for the early life stages of aquatic animals.
Assuntos
Organismos Aquáticos/efeitos dos fármacos , Estágios do Ciclo de Vida/efeitos dos fármacos , Microplásticos/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Organismos Aquáticos/crescimento & desenvolvimento , Ecossistema , Ecotoxicologia , Ilhas , Microplásticos/química , Cifozoários/efeitos dos fármacos , Cifozoários/crescimento & desenvolvimento , Ouriços-do-Mar/efeitos dos fármacos , Ouriços-do-Mar/crescimento & desenvolvimento , Poluentes Químicos da Água/químicaRESUMO
Glucose 6-phosphate dehydrogenase (G6PDH) fulfills an essential role in cell physiology by catalyzing the production of NADPH+ and of a precursor for the de novo synthesis of ribose 5-phosphate. In trypanosomatids, G6PDH is essential for in vitro proliferation, antioxidant defense and, thereby, drug resistance mechanisms. So far, 16α-brominated epiandrosterone represents the most potent hit targeting trypanosomal G6PDH. Here, we extended the investigations on this important drug target and its inhibition by using a small subset of androstane derivatives. In Trypanosoma cruzi, immunofluorescence revealed a cytoplasmic distribution of G6PDH and the absence of signal in major organelles. Cytochemical assays confirmed parasitic G6PDH as the molecular target of epiandrosterone. Structure-activity analysis for a set of new (dehydro)epiandrosterone derivatives revealed that bromination at position 16α of the cyclopentane moiety yielded more potent T. cruzi G6PDH inhibitors than the corresponding ß-substituted analogues. For the 16α brominated compounds, the inclusion of an acetoxy group at position 3 either proved detrimental or enhanced the activity of the epiandrosterone or the dehydroepiandrosterone derivatives, respectively. Most derivatives presented single digit µM EC50 against infective T. brucei and the killing mechanism involved an early thiol-redox unbalance. This data suggests that infective African trypanosomes lack efficient NADPH+-synthesizing pathways, beyond the Pentose Phosphate, to maintain thiol-redox homeostasis.
Assuntos
Glucosefosfato Desidrogenase/metabolismo , Estágios do Ciclo de Vida , Esteroides/farmacologia , Trypanosoma brucei brucei/enzimologia , Trypanosoma brucei brucei/crescimento & desenvolvimento , Androsterona/química , Androsterona/farmacologia , Sítios de Ligação , Citosol/enzimologia , Desidroepiandrosterona/química , Desidroepiandrosterona/farmacologia , Glucosefosfato Desidrogenase/antagonistas & inibidores , Glucosefosfato Desidrogenase/química , Humanos , Estágios do Ciclo de Vida/efeitos dos fármacos , Modelos Moleculares , Oxirredução , Reprodutibilidade dos Testes , Trypanosoma brucei brucei/efeitos dos fármacosRESUMO
The protozoan diseases Human African Trypanosomiasis (HAT), Chagas disease (CD), and leishmaniases span worldwide and therefore their impact is a universal concern. The present regimen against kinetoplastid protozoan infections is poor and insufficient. Target-based design expands the horizon of drug design and development and offers novel chemical entities and potential drug candidates to the therapeutic arsenal against the aforementioned neglected diseases. In this review, we report the most promising targets of the main kinetoplastid parasites, as well as their corresponding inhibitors. This overview is part of the Special Issue, entitled "Advances of Medicinal Chemistry against Kinetoplastid Protozoa (Trypanosoma brucei, Trypanosoma cruzi and Leishmania spp.) Infections: Drug Design, Synthesis and Pharmacology".
Assuntos
Antiprotozoários/farmacologia , Doença de Chagas/tratamento farmacológico , Desenho de Fármacos , Leishmaniose/tratamento farmacológico , Terapia de Alvo Molecular/métodos , Tripanossomíase Africana/tratamento farmacológico , Animais , Antiprotozoários/síntese química , Antiprotozoários/classificação , Doença de Chagas/parasitologia , Doença de Chagas/transmissão , Descoberta de Drogas , Humanos , Insetos Vetores/efeitos dos fármacos , Insetos Vetores/parasitologia , Leishmania/efeitos dos fármacos , Leishmania/genética , Leishmania/crescimento & desenvolvimento , Leishmania/metabolismo , Leishmaniose/parasitologia , Leishmaniose/transmissão , Estágios do Ciclo de Vida/efeitos dos fármacos , Estágios do Ciclo de Vida/genética , Redes e Vias Metabólicas/efeitos dos fármacos , Redes e Vias Metabólicas/genética , Estrutura Molecular , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Relação Estrutura-Atividade , Trypanosoma brucei gambiense/efeitos dos fármacos , Trypanosoma brucei gambiense/genética , Trypanosoma brucei gambiense/crescimento & desenvolvimento , Trypanosoma brucei gambiense/metabolismo , Trypanosoma cruzi/efeitos dos fármacos , Trypanosoma cruzi/genética , Trypanosoma cruzi/crescimento & desenvolvimento , Trypanosoma cruzi/metabolismo , Tripanossomíase Africana/parasitologia , Tripanossomíase Africana/transmissãoRESUMO
The present study aimed to evaluate the risk assessment, median lethal concentration LC50-96h, development, and mortality of Nile tilapia Oreochromis niloticus larvae exposed to atrazine after stress management. An LC50-96h trial was carried out using fish (n = 147; 8.5 ± 1.0 mg; seven larvae/aquarium), which were allocated randomly in 21 aquaria (1 L) and exposed to five concentrations of atrazine: 2, 4, 8, 16, and 32 mg L-1 plus one control (without herbicide) and a control with a solubility adjuvant (acetone). Temperature, pH, dissolved oxygen, conductivity, and total ammonia were measured daily. In addition, a stress test was performed with fish (n = 150; 17.9 ± 1.7 mg; 10 larvae/aquarium) submitted to air exposition (five minutes) and posteriorly distributed randomly in 15 aquaria (1 L), and exposed to atrazine at 0.18, 6, 12, and 18 mg L-1. The LC50-96h of atrazine for Nile tilapia larvae was 17.87 mg L-1. Significant differences (P < 0.05) were found for weight and final length, pH, and dissolved oxygen that was responsive to the increased levels of herbicide. Larvae mortality post-stress was registered to 6, 12, and 18 mg L-1 of atrazine, and was more critical at 24 h. The increased doses of atrazine used in LC50-96h test depressed the development of Nile tilapia larvae. Fish submitted to stress (air exposition) and exposed to sub-lethal doses of atrazine showed significant mortality, indicating that stressors may increase the toxic effect of atrazine for Nile tilapia larvae. On the other hand, based on risk assessment atrazine can be classified as herbicide with low toxicity for Nile tilapia larvae and low toxicological risk.
Assuntos
Atrazina/toxicidade , Ciclídeos/crescimento & desenvolvimento , Herbicidas/toxicidade , Estágios do Ciclo de Vida/efeitos dos fármacos , Poluentes Químicos da Água/toxicidade , Animais , Relação Dose-Resposta a Droga , Dose Letal Mediana , Medição de Risco , Testes de Toxicidade AgudaRESUMO
Inhibitors of Apoptosis Protein (IAP) genes participate in processes like apoptosis, proliferation, innate immunity, inflammation, cell motility, differentiation and in malignancies. Here we reveal 25 IAP genes in the tunicate Botryllus schlosseri's genome and their functions in two developmental biology phenomena, a new mode of whole body regeneration (WBR) induced by budectomy, and blastogenesis, the four-staged cycles of botryllid ascidian astogeny. IAP genes that were specifically upregulated during these developmental phenomena were identified, and protein expression patterns of one of these genes, IAP28, were followed. Most of the IAP genes upregulation recorded at blastogenetic stages C/D was in concert with the upregulation at 100⯵M H2O2 apoptotic-induced treatment and in parallel to expressions of AIF1, Bax, Mcl1, caspase 2 and two orthologues of caspase 7. Wnt agonist altered the takeover duration along with reduced IAP expressions, and displacement of IAP28+ phagocytes. WBR was initiated solely at blastogenetic stage D, where zooidal absorption was attenuated and regeneration centers were formed either from remains of partially absorbed zooids or from deformed ampullae. Subsequently, bud-bearing zooids developed, in concert with a massive IAP28-dependent phagocytic wave that eliminated the old zooids, then proceeded with the establishment of morphologically normal-looking colonies. IAP4, IAP14 and IAP28 were also involved in WBR, in conjunction with the expression of the pro-survival PI3K-Akt pathway. IAPs function deregulation by Smac mimetics resulted in severe morphological damages, attenuation in bud growth and differentiation, and in destabilization of colonial coordination. Longtime knockdown of IAP functions prior to the budectomy, resulted in colonial death.
Assuntos
Proteínas Inibidoras de Apoptose/genética , Regeneração/genética , Urocordados/genética , Urocordados/fisiologia , Animais , Apoptose/efeitos dos fármacos , Apoptose/genética , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Peróxido de Hidrogênio/administração & dosagem , Peróxido de Hidrogênio/toxicidade , Proteínas Inibidoras de Apoptose/metabolismo , Estágios do Ciclo de Vida/efeitos dos fármacos , Estágios do Ciclo de Vida/genética , Família Multigênica , Regeneração/efeitos dos fármacos , Urocordados/efeitos dos fármacos , Urocordados/embriologia , Proteínas Wnt/agonistas , Proteínas Wnt/metabolismoRESUMO
Entamoeba histolytica and its reptilian counterpart and encystation model Entamoeba invadens formed a polarized monopodial morphology when treated with pentoxifylline. This morphology was propelled by retrograde flow of the cell surface resulting from a cyclic sol-gel conversion of cytoplasm and a stable bleb at the leading edge. Pentoxifylline treatment switched the unpolarized, adherent trophozoites to the nonadherent, stable bleb-driven form and altered the motility pattern from slow and random to fast, directionally persistent, and highly chemotactic. Interestingly, exogenously added adenosine produced multiple protrusions and random motility, an opposite phenotype to that of pentoxifylline. Thus, pentoxifylline, an adenosine antagonist, may be inducing the monopodial morphology by preventing lateral protrusions and restricting the leading edge to one site. The polarized form of E. invadens was aggregation competent, and time-lapse microscopy of encystation revealed its appearance during early hours, mediating the cell aggregation by directional cell migration. The addition of purine nucleotides to in vitro encystation culture prevented the formation of polarized morphology and inhibited the cell aggregation and, thus, the encystation, which further showed the importance of the polarized form in the Entamoeba life cycle. Cell polarity and motility are essential in the pathogenesis of Entamoeba parasites, and the stable bleb-driven polarized morphology of Entamoeba may also be important in invasive amoebiasis.