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1.
Sci Adv ; 7(27)2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34193418

RESUMO

The global outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) necessitates the rapid development of new therapies against coronavirus disease 2019 (COVID-19) infection. Here, we present the identification of 200 approved drugs, appropriate for repurposing against COVID-19. We constructed a SARS-CoV-2-induced protein network, based on disease signatures defined by COVID-19 multiomics datasets, and cross-examined these pathways against approved drugs. This analysis identified 200 drugs predicted to target SARS-CoV-2-induced pathways, 40 of which are already in COVID-19 clinical trials, testifying to the validity of the approach. Using artificial neural network analysis, we classified these 200 drugs into nine distinct pathways, within two overarching mechanisms of action (MoAs): viral replication (126) and immune response (74). Two drugs (proguanil and sulfasalazine) implicated in viral replication were shown to inhibit replication in cell assays. This unbiased and validated analysis opens new avenues for the rapid repurposing of approved drugs into clinical trials.


Assuntos
Reposicionamento de Medicamentos , SARS-CoV-2/fisiologia , Antivirais/metabolismo , Antivirais/farmacologia , Antivirais/uso terapêutico , COVID-19/tratamento farmacológico , COVID-19/patologia , COVID-19/virologia , Humanos , Redes Neurais de Computação , Proguanil/farmacologia , Proguanil/uso terapêutico , SARS-CoV-2/imunologia , SARS-CoV-2/isolamento & purificação , Sulfassalazina/farmacologia , Replicação Viral/efeitos dos fármacos
2.
J Enzyme Inhib Med Chem ; 36(1): 198-206, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33530764

RESUMO

In various malaria-endemic regions, the appearance of resistance has precluded the use of pyrimidine-based antifolate drugs. Here, a three-step fragment screening was used to identify new non-pyrimidine Plasmodium falciparum dihydrofolate reductase (PfDHFR) inhibitors. Starting from a 1163-fragment commercial library, a two-step differential scanning fluorimetry screen identified 75 primary fragment hits. Subsequent enzyme inhibition assay identified 11 fragments displaying IC50 in the 28-695 µM range and selectivity for PfDHFR. In addition to the known pyrimidine, three new anti-PfDHFR chemotypes were identified. Fragments from each chemotype were successfully co-crystallized with PfDHFR, revealing a binding in the active site, in the vicinity of catalytic residues, which was confirmed by molecular docking on all fragment hits. Finally, comparison with similar non-hit fragments provides preliminary input on available growth vectors for future drug development.


Assuntos
Antimaláricos/farmacologia , Descoberta de Drogas , Inibidores Enzimáticos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Proteínas de Protozoários/antagonistas & inibidores , Antimaláricos/síntese química , Antimaláricos/química , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Modelos Moleculares , Simulação de Acoplamento Molecular , Estrutura Molecular , Plasmodium falciparum/enzimologia , Proguanil/síntese química , Proguanil/química , Proguanil/farmacologia , Proteínas de Protozoários/isolamento & purificação , Proteínas de Protozoários/metabolismo , Pirimetamina/síntese química , Pirimetamina/química , Pirimetamina/farmacologia , Relação Estrutura-Atividade , Tetra-Hidrofolato Desidrogenase/isolamento & purificação , Tetra-Hidrofolato Desidrogenase/metabolismo , Triazinas/síntese química , Triazinas/química , Triazinas/farmacologia
3.
Biochem Biophys Res Commun ; 534: 94-98, 2021 01 01.
Artigo em Inglês | MEDLINE | ID: mdl-33316545

RESUMO

Proguanil in combination with its synergistic partner atovaquone has been used for malaria treatment and prophylaxis for decades. However its mode of action is not fully understood. Here we used yeast to investigate its activity. Proguanil inhibits yeast growth, causes cell death and acts in synergy with atovaquone. It was previously proposed that the drug would target the system that maintains the mitochondrial membrane potential when the respiratory chain is inhibited. However our data did not seem to validate that hypothesis. We proposed that proguanil would not have a specific target but accumulate in the mitochondrial to concentrations that impair multiple mitochondrial functions leading to cell death. Selection and study of proguanil resistant mutants pointed towards an unexpected resistance mechanism: the decrease of CoQ level, which possibly alters the mitochondrial membrane properties and lowers proguanil intramitochondrial level.


Assuntos
Antimaláricos/farmacologia , Proguanil/farmacologia , Leveduras/efeitos dos fármacos , Atovaquona/farmacologia , Farmacorresistência Fúngica/efeitos dos fármacos , Farmacorresistência Fúngica/genética , Sinergismo Farmacológico , Quimioterapia Combinada , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Mutação , Oxigênio/metabolismo , Pirimidinas/farmacologia , Estrobilurinas/farmacologia , Ubiquinona/análogos & derivados , Ubiquinona/metabolismo , Ubiquinona/farmacologia , Vitamina K 3/análogos & derivados , Vitamina K 3/farmacologia , Leveduras/genética , Leveduras/crescimento & desenvolvimento
4.
Parasit Vectors ; 13(1): 137, 2020 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-32171330

RESUMO

BACKGROUND: Routine molecular surveillance for imported drug-resistant malaria parasites to the USA and European Union is an important public health activity. The obtained molecular data are used to help keep chemoprophylaxis and treatment guidelines up to date for persons traveling to malaria endemic countries. Recent advances in next-generation sequencing (NGS) technologies provide a new and effective way of tracking malaria drug-resistant parasites. METHODS: As part of a technology transfer arrangement between the CDC Malaria Branch and the Istituto Superiore di Sanità (ISS), Rome, Italy, the recently described Malaria Resistance Surveillance (MaRS) protocol was used to genotype 148 Plasmodium falciparum isolates from Eritrea for kelch 13 (k13) and cytochrome b (cytb) genes, molecular markers associated with resistance to artemisinin (ART) and atovaquone/proguanil (AP), respectively. RESULTS: Spanning the full-length k13 gene, seven non-synonymous single nucleotide polymorphisms (SNPs) were found (K189N, K189T, E208K, D281V, E401Q, R622I and T535M), of which none have been associated with artemisinin resistance. No mutations were found in cytochrome b. CONCLUSION: All patients successfully genotyped carried parasites susceptible to ART and AP treatment. Future studies between CDC Malaria Branch and ISS are planned to expand the MaRS system, including data sharing, in an effort to maintain up to date treatment guidelines for travelers to malaria endemic countries.


Assuntos
Citocromos b/genética , Resistência a Medicamentos/genética , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Plasmodium falciparum/genética , Plasmodium falciparum/isolamento & purificação , Proteínas de Protozoários/genética , África , Anti-Infecciosos/farmacologia , Antimaláricos/farmacologia , Artemisininas , Atovaquona/farmacologia , DNA de Protozoário/genética , Proteínas de Drosophila , Combinação de Medicamentos , Genótipo , Humanos , Itália , Malária Falciparum/parasitologia , Malária Falciparum/prevenção & controle , Proteínas dos Microfilamentos/genética , Plasmodium falciparum/efeitos dos fármacos , Polimorfismo de Nucleotídeo Único , Prevalência , Proguanil/farmacologia , Viagem
5.
Artigo em Inglês | MEDLINE | ID: mdl-32094134

RESUMO

Quinolones, such as the antimalarial atovaquone, are inhibitors of the malarial mitochondrial cytochrome bc 1 complex, a target critical to the survival of both liver- and blood-stage parasites, making these drugs useful as both prophylaxis and treatment. Recently, several derivatives of endochin have been optimized to produce novel quinolones that are active in vitro and in animal models. While these quinolones exhibit potent ex vivo activity against Plasmodium falciparum and Plasmodium vivax, their activity against the zoonotic agent Plasmodium knowlesi is unknown. We screened several of these novel endochin-like quinolones (ELQs) for their activity against P. knowlesi in vitro and compared this with their activity against P. falciparum tested under identical conditions. We demonstrated that ELQs are potent against P. knowlesi (50% effective concentration, <117 nM) and equally effective against P. falciparum We then screened selected quinolones and partner drugs using a longer exposure (2.5 life cycles) and found that proguanil is 10-fold less potent against P. knowlesi than P. falciparum, while the quinolones demonstrate similar potency. Finally, we used isobologram analysis to compare combinations of the ELQs with either proguanil or atovaquone. We show that all quinolone combinations with proguanil are synergistic against P. falciparum However, against P. knowlesi, no evidence of synergy between proguanil and the quinolones was found. Importantly, the combination of the novel quinolone ELQ-300 with atovaquone was synergistic against both species. Our data identify potentially important species differences in proguanil susceptibility and in the interaction of proguanil with quinolones and support the ongoing development of novel quinolones as potent antimalarials that target multiple species.


Assuntos
Antimaláricos/farmacologia , Plasmodium knowlesi/efeitos dos fármacos , Proguanil/farmacologia , Quinolonas/farmacologia , Animais , Atovaquona/farmacologia , Interações Medicamentosas , Sinergismo Farmacológico , Testes de Sensibilidade Microbiana , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium knowlesi/crescimento & desenvolvimento
6.
Artigo em Inglês | MEDLINE | ID: mdl-31964796

RESUMO

Drug repositioning offers an effective alternative to de novo drug design to tackle the urgent need for novel antimalarial treatments. The antiamoebic compound emetine dihydrochloride has been identified as a potent in vitro inhibitor of the multidrug-resistant strain K1 of Plasmodium falciparum (50% inhibitory concentration [IC50], 47 nM ± 2.1 nM [mean ± standard deviation]). Dehydroemetine, a synthetic analogue of emetine dihydrochloride, has been reported to have less-cardiotoxic effects than emetine. The structures of two diastereomers of dehydroemetine were modeled on the published emetine binding site on the cryo-electron microscopy (cryo-EM) structure with PDB code 3J7A (P. falciparum 80S ribosome in complex with emetine), and it was found that (-)-R,S-dehydroemetine mimicked the bound pose of emetine more closely than did (-)-S,S-dehydroisoemetine. (-)-R,S-dehydroemetine (IC50 71.03 ± 6.1 nM) was also found to be highly potent against the multidrug-resistant K1 strain of P. falciparum compared with (-)-S,S-dehydroisoemetine (IC50, 2.07 ± 0.26 µM), which loses its potency due to the change of configuration at C-1'. In addition to its effect on the asexual erythrocytic stages of P. falciparum, the compound exhibited gametocidal properties with no cross-resistance against any of the multidrug-resistant strains tested. Drug interaction studies showed (-)-R,S-dehydroemetine to have synergistic antimalarial activity with atovaquone and proguanil. Emetine dihydrochloride and (-)-R,S-dehydroemetine failed to show any inhibition of the hERG potassium channel and displayed activity affecting the mitochondrial membrane potential, indicating a possible multimodal mechanism of action.


Assuntos
Antimaláricos/farmacologia , Reposicionamento de Medicamentos , Emetina/análogos & derivados , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Antimaláricos/efeitos adversos , Atovaquona/farmacologia , Linhagem Celular Tumoral , Resistência a Múltiplos Medicamentos/genética , Sinergismo Farmacológico , Emetina/efeitos adversos , Emetina/química , Emetina/farmacologia , Feminino , Células Hep G2 , Humanos , Masculino , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Plasmodium falciparum/genética , Proguanil/farmacologia , Estereoisomerismo
7.
Bioorg Med Chem ; 28(2): 115258, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31864776

RESUMO

Proguanil, a member of biguanide family, has excellent anti-proliferative activities. Fluorine-containing compounds have been demonstrated to have super biological activities including enhanced binding interactions, metabolic stability, and reduced toxicity. In this study, based on the intermediate derivatization methods, we synthesized 13 new fluorine-containing proguanil derivatives, and found that 7a,7d and 8e had much lower IC50 than proguanil in 5 human cancerous cell lines. The results of clonogenic and scratch wound healing assays revealed that the inhibitory effects of derivatives 7a,7d and 8e on proliferation and migration of human cancer cell lines were much better than proguanil as well. Mechanistic study based on representative derivative 7a indicated that this compound up-regulates AMPK signal pathway and downregulates mTOR/4EBP1/p70S6K. In conclusion, these new fluorine-containing derivatives show potential for the development of cancer chemotherapeutic drugs.


Assuntos
Antineoplásicos/farmacologia , Flúor/farmacologia , Proguanil/farmacologia , Antineoplásicos/síntese química , Antineoplásicos/química , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Flúor/química , Humanos , Estrutura Molecular , Proguanil/síntese química , Proguanil/química , Relação Estrutura-Atividade , Células Tumorais Cultivadas
8.
Commun Biol ; 2: 166, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31069275

RESUMO

Atovaquone-proguanil (Malarone®) is used for malaria prophylaxis and treatment. While the cytochrome bc1-inhibitor atovaquone has potent activity, proguanil's action is attributed to its cyclization-metabolite, cycloguanil. Evidence suggests that proguanil has limited intrinsic activity, associated with mitochondrial-function. Here we demonstrate that proguanil, and cyclization-blocked analogue tBuPG, have potent, but slow-acting, in vitro anti-plasmodial activity. Activity is folate-metabolism and isoprenoid biosynthesis-independent. In yeast dihydroorotate dehydrogenase-expressing parasites, proguanil and tBuPG slow-action remains, while bc1-inhibitor activity switches from comparatively fast to slow-acting. Like proguanil, tBuPG has activity against P. berghei liver-stage parasites. Both analogues act synergistically with bc1-inhibitors against blood-stages in vitro, however cycloguanil antagonizes activity. Together, these data suggest that proguanil is a potent slow-acting anti-plasmodial agent, that bc1 is essential to parasite survival independent of dihydroorotate dehydrogenase-activity, that Malarone® is a triple-drug combination that includes antagonistic partners and that a cyclization-blocked proguanil may be a superior combination partner for bc1-inhibitors in vivo.


Assuntos
Antimaláricos/farmacologia , Atovaquona/farmacologia , Inibidores Enzimáticos/farmacologia , Plasmodium berghei/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Proguanil/análogos & derivados , Animais , Anopheles , Antimaláricos/química , Atovaquona/química , Ciclização/efeitos dos fármacos , Relação Dose-Resposta a Droga , Combinação de Medicamentos , Complexo III da Cadeia de Transporte de Elétrons/antagonistas & inibidores , Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Inibidores Enzimáticos/química , Eritrócitos/efeitos dos fármacos , Eritrócitos/parasitologia , Ácido Fólico/metabolismo , Células Hep G2 , Humanos , Concentração Inibidora 50 , Fígado/efeitos dos fármacos , Fígado/parasitologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Plasmodium berghei/crescimento & desenvolvimento , Plasmodium berghei/metabolismo , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium falciparum/metabolismo , Proguanil/química , Proguanil/farmacologia , Esporozoítos/efeitos dos fármacos , Esporozoítos/crescimento & desenvolvimento , Esporozoítos/metabolismo , Terpenos/metabolismo , Triazinas/química , Triazinas/farmacologia
9.
ACS Infect Dis ; 5(7): 1105-1114, 2019 07 12.
Artigo em Inglês | MEDLINE | ID: mdl-31012301

RESUMO

Cycloguanil is a known dihydrofolate-reductase (DHFR) inhibitor, but there is no evidence of its activity on pteridine reductase (PTR), the main metabolic bypass to DHFR inhibition in trypanosomatid parasites. Here, we provide experimental evidence of cycloguanil as an inhibitor of Trypanosoma brucei PTR1 (TbPTR1). A small library of cycloguanil derivatives was developed, resulting in 1 and 2a having IC50 values of 692 and 186 nM, respectively, toward TbPTR1. Structural analysis revealed that the increased potency of 1 and 2a is due to the combined contributions of hydrophobic interactions, H-bonds, and halogen bonds. Moreover, in vitro cell-growth-inhibition tests indicated that 2a is also effective on T. brucei. The simultaneous inhibition of DHFR and PTR1 activity in T. brucei is a promising new strategy for the treatment of human African trypanosomiasis. For this purpose, 1,6-dihydrotriazines represent new molecular tools to develop potent dual PTR and DHFR inhibitors.


Assuntos
Oxirredutases/antagonistas & inibidores , Proguanil/química , Triazinas/síntese química , Tripanossomicidas/síntese química , Trypanosoma brucei brucei/enzimologia , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Estrutura Molecular , Oxirredutases/química , Proguanil/farmacologia , Proteínas de Protozoários/antagonistas & inibidores , Proteínas de Protozoários/química , Bibliotecas de Moléculas Pequenas/síntese química , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/farmacologia , Relação Estrutura-Atividade , Triazinas/química , Triazinas/farmacologia , Tripanossomicidas/química , Tripanossomicidas/farmacologia , Trypanosoma brucei brucei/efeitos dos fármacos
10.
J Infect Dis ; 220(3): 535-539, 2019 07 02.
Artigo em Inglês | MEDLINE | ID: mdl-30877300

RESUMO

Pitting, the removal of dead parasites from their host erythrocyte, has been studied in patients with severe malaria treated parenterally with quinine or artesunate, and was recently shown to contribute to delayed hemolysis, a frequent adverse event of artesunate. We quantified pitting in 81 travelers treated with oral antimalarial therapy. Pitting rate was high (55.8%) with artemisinin-based combinations, but <10% with the nonartemisinin drugs quinine, mefloquine, and atovaquone-proguanil. This may, in part, explain the slower parasite clearance in patients treated with antimalarial drugs lacking an artemisinin component, as well as the absence of posttreatment hemolysis with these drugs.


Assuntos
Antimaláricos/farmacologia , Artemisininas/farmacologia , Atovaquona/farmacologia , Malária Falciparum/tratamento farmacológico , Mefloquina/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Proguanil/farmacologia , Adolescente , Adulto , Artesunato/farmacologia , Criança , Combinação de Medicamentos , Feminino , Humanos , Malária Falciparum/parasitologia , Masculino , Pessoa de Meia-Idade , Adulto Jovem
11.
SAR QSAR Environ Res ; 29(12): 957-974, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30381963

RESUMO

A series of antifolate compounds, i.e. 1-(4-chlorophenyl)-6,6-dimethyl-1,3,5-triazine-2,4-diamine, or cycloguanil analogues, have shown effective inhibiting properties against Plasmodium falciparum dihydrofolate reductase (PfDHFR). In this work, the stereoselectivity of PfDHFR to the R and S enantiomer of cycloguanil analogues was obtained from molecular docking calculations and integrated into QSAR study to obtain a more accurate prediction model. Results indicate that PfDHFR can bind to cycloguanil analogues in the R and S enantiomers. Cycloguanil analogues with alkyl chain substituent prefer the R enantiomer over S because they do not experience steric hindrance with the Phe58 side chain, while cycloguanil analogues with phenol chain substituent prefer the S enantiomer over R because they do not experience steric hindrance with Leu46 and Met55 side chains. Particle swarm optimization and support vector regression were used to select relevant descriptors and generate the effective prediction model, with a high statistical significance level (r2training = 0.941; r2test = 0.884).


Assuntos
Aprendizado de Máquina , Simulação de Acoplamento Molecular , Proguanil/química , Proguanil/farmacologia , Triazinas/química , Triazinas/farmacologia , Algoritmos , Antimaláricos/química , Inibidores Enzimáticos/química , Antagonistas do Ácido Fólico/química , Estrutura Molecular , Plasmodium falciparum/enzimologia , Proguanil/metabolismo , Ligação Proteica , Relação Quantitativa Estrutura-Atividade , Reprodutibilidade dos Testes , Estereoisomerismo , Especificidade por Substrato , Tetra-Hidrofolato Desidrogenase/metabolismo , Triazinas/metabolismo
12.
Anticancer Res ; 38(9): 5003-5011, 2018 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-30194144

RESUMO

Background/ Aim: There is evidence that inhibitory effects of biguanides on oxidative phosphorylation require uptake of biguanides into the mitochondria. In this study the action of two biguanides that enter the mitochondria (buformin and phenformin) were compared with the action of two biguanides with poor uptake (phenyl biguanide and proguanil). MATERIALS AND METHODS: Effects on growth, glucose uptake and medium acidification were studied with two human colon cancer cells and seven bladder cancer cell lines. RESULTS: Growth inhibition was greatest with proguanil followed by phenformin, buformin and phenylbiguanide. In contrast, increased glucose uptake and acidification of the medium was observed with buformin and phenformin, with no change or less acidification of the medium with phenyl biguanide and proguanil. CONCLUSION: The effect of biguanides on glucose metabolism requires mitochondrial uptake while the mechanism for growth inhibition by biguanides remains to be defined.


Assuntos
Biguanidas/farmacologia , Neoplasias do Colo/metabolismo , Glicólise/efeitos dos fármacos , Hipoglicemiantes/farmacologia , Neoplasias da Bexiga Urinária/metabolismo , Buformina/farmacologia , Células CACO-2 , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Meios de Cultura/química , Glucose/metabolismo , Células HT29 , Humanos , Concentração de Íons de Hidrogênio , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Fenformin/farmacologia , Proguanil/farmacologia
13.
Parasitol Int ; 67(6): 787-792, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30114522

RESUMO

Malaria caused by an infection of Plasmodium knowlesi can result in high parasitemia and deaths. Therefore, effective and prompt treatment is necessary to reduce morbidity and mortality. The study aims to characterize P. knowlesi dihydrofolate reductase-thymidylate synthase enzyme (PkDHFR-TS) and its sensitivity to antifolates. The putative Pkdhfr gene was PCR amplified from field isolates collected from the Southern Thailand. Molecular analysis showed 11 polymorphisms in the dhfr domain of the bifunctional dhfr-ts gene. Of these, 1 polymorphism was a non-synonymous substitution (R34L) that had previously been reported but not associated with antifolate resistance. The recombinant PkDHFR-TS enzyme was found to be sensitive to standard antifolates-pyrimethamine and cycloguanil-as well as P218, a registered candidate drug currently first in human clinical trial. Results suggest that antifolates class of compounds should be effective against P. knowlesi infection.


Assuntos
Antimaláricos/farmacologia , Antagonistas do Ácido Fólico/farmacologia , Complexos Multienzimáticos/antagonistas & inibidores , Plasmodium knowlesi/efeitos dos fármacos , Proteínas de Protozoários/antagonistas & inibidores , Timidilato Sintase/antagonistas & inibidores , Sequência de Bases , Complexos Multienzimáticos/genética , Complexos Multienzimáticos/metabolismo , Plasmodium knowlesi/genética , Proguanil/farmacologia , Proteínas de Protozoários/genética , Proteínas de Protozoários/metabolismo , Pirimetamina/farmacologia , Alinhamento de Sequência , Tetra-Hidrofolato Desidrogenase/genética , Tetra-Hidrofolato Desidrogenase/metabolismo , Timidilato Sintase/genética , Timidilato Sintase/metabolismo , Triazinas/farmacologia
14.
JCI Insight ; 3(1)2018 01 11.
Artigo em Inglês | MEDLINE | ID: mdl-29321371

RESUMO

Malaria eradication necessitates new tools to fight the evolving and complex Plasmodium pathogens. These tools include prophylactic drugs that eliminate Plasmodium liver stages and consequently prevent clinical disease, decrease transmission, and reduce the propensity for resistance development. Currently, the identification of these drugs relies on in vitro P. falciparum liver stage assays or in vivo causal prophylaxis assays using rodent malaria parasites; there is no method to directly test in vivo liver stage activity of candidate antimalarials against the human malaria-causing parasite P. falciparum. Here, we use a liver-chimeric humanized mouse (FRG huHep) to demonstrate in vivo P. falciparum liver stage development and describe the efficacy of clinically used and candidate antimalarials with prophylactic activity. We show that daily administration of atovaquone-proguanil (ATQ-PG; ATQ, 30 mg/kg, and PG, 10 mg/kg) protects 5 of 5 mice from liver stage infection, consistent with the use in humans as a causal prophylactic drug. Single-dose primaquine (60 mg/kg) has similar activity to that observed in humans, demonstrating the activity of this drug (and its active metabolites) in FRG huHep mice. We also show that DSM265, a selective Plasmodial dihydroorotate dehydrogenase inhibitor with causal prophylactic activity in humans, reduces liver stage burden in FRG huHep mice. Finally, we measured liver stage-to-blood stage transition of the parasite, the ultimate readout of prophylactic activity and measurement of infective capacity of parasites in the liver, to show that ATQ-PG reduces blood stage patency to below the limit of quantitation by quantitative PCR (qPCR). The FRG huHep model, thus, provides a platform for preclinical evaluation of drug candidates for liver stage causal prophylactic activity, pharmacokinetic/pharmacodynamics studies, and biological studies to investigate the mechanism of action of liver stage active antimalarials.


Assuntos
Antimaláricos/farmacologia , Fígado/efeitos dos fármacos , Fígado/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Animais , Atovaquona/farmacologia , Modelos Animais de Doenças , Combinação de Medicamentos , Avaliação Pré-Clínica de Medicamentos , Malária Falciparum/tratamento farmacológico , Camundongos , Proguanil/farmacologia , Pirimidinas/farmacologia , Triazóis/farmacologia
15.
Clin Infect Dis ; 66(11): 1751-1755, 2018 05 17.
Artigo em Inglês | MEDLINE | ID: mdl-29228132

RESUMO

Background: Atovaquone-proguanil is considered causal prophylaxis (inhibition of liver-stage schizonts) for Plasmodium falciparum; however, its causal prophylactic efficacy for Plasmodium vivax is not known. Travelers returning to nonendemic areas provide a unique opportunity to study P. vivax prophylaxis. Methods: In a retrospective observational study, for 11 years, Israeli rafters who had traveled to the Omo River in Ethiopia, a highly malaria-endemic area, were followed for at least 1 year after their return. Malaria prophylaxis used during this period included mefloquine, doxycycline, primaquine, and atovaquone-proguanil. Prophylaxis failure was divided into early (within a month of exposure) and late malaria. Results: Two hundred fifty-two travelers were included in the study. Sixty-two (24.6%) travelers developed malaria, 56 (91.9%) caused by P. vivax, with 54 (87.1%) cases considered as late malaria. Among travelers using atovaquone-proguanil, there were no cases of early P. falciparum or P. vivax malaria. However, 50.0% of atovaquone-proguanil users developed late vivax malaria, as did 46.5% and 43.5% of mefloquine and doxycycline users, respectively; only 2 (1.4%) primaquine users developed late malaria (P < .0001). Conclusions: Short-course atovaquone-proguanil appears to provide causal (liver schizont stage) prophylaxis for P. vivax, but is ineffective against late, hypnozoite reactivation-related attacks. These findings suggest that primaquine should be considered as the chemoprophylactic agent of choice for areas with high co-circulation of P. falciparum and P. vivax.


Assuntos
Antimaláricos/farmacologia , Atovaquona/farmacologia , Malária Vivax/prevenção & controle , Proguanil/farmacologia , Adulto , Idoso , Antígenos de Protozoários , Antimaláricos/administração & dosagem , Atovaquona/administração & dosagem , Combinação de Medicamentos , Quimioterapia Combinada , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Proguanil/administração & dosagem , Estudos Retrospectivos , Viagem , Adulto Jovem
16.
J Antimicrob Chemother ; 73(3): 581-595, 2018 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-29237012

RESUMO

Background: Atovaquone/proguanil, registered as Malarone®, is a fixed-dose combination recommended for first-line treatment of uncomplicated Plasmodium falciparum malaria in non-endemic countries and its prevention in travellers. Mutations in the cytochrome bc1 complex are causally associated with atovaquone resistance. Methods: This systematic review assesses the clinical efficacy of atovaquone/proguanil treatment of uncomplicated malaria and examines the extent to which codon 268 mutation in cytochrome b influences treatment failure and recrudescence based on published information. Results: Data suggest that atovaquone/proguanil treatment efficacy is 89%-98% for P. falciparum malaria (from 27 studies including between 18 and 253 patients in each case) and 20%-26% for Plasmodium vivax malaria (from 1 study including 25 patients). The in vitro P. falciparum phenotype of atovaquone resistance is an IC50 value >28 nM. Case report analyses predict that recrudescence in a patient presenting with parasites carrying cytochrome b codon 268 mutation will occur on average at day 29 (95% CI: 22, 35), 19 (95% CI: 7, 30) days longer than if the mutation is absent. Conclusions: Evidence suggests atovaquone/proguanil treatment for P. falciparum malaria is effective. Late treatment failure is likely to be associated with a codon 268 mutation in cytochrome b, though recent evidence from animal models suggests these mutations may not spread within the population. However, early treatment failure is likely to arise through alternative mechanisms, requiring further investigation.


Assuntos
Atovaquona/farmacologia , Resistência a Múltiplos Medicamentos/genética , Malária Falciparum/tratamento farmacológico , Malária Vivax/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Proguanil/farmacologia , Falha de Tratamento , Combinação de Medicamentos , Quimioterapia Combinada , Complexo III da Cadeia de Transporte de Elétrons/genética , Humanos , Malária Falciparum/prevenção & controle , Malária Vivax/prevenção & controle , Mutação , Viagem
17.
PLoS One ; 12(12): e0188754, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29244851

RESUMO

SEVERE MALARIA: Even with the best available treatment, the mortality from severe Plasmodium falciparum malaria remains high. Typical features at death are high parasite loads and obstructed micro- vasculature. Infected erythrocytes (IE) containing mature parasites bind to the host receptor heparan sulfate, which is also an important receptor for merozoite invasion. To block merozoite invasion has not previously been proposed as an adjunctive therapeutic approach but it may preclude the early expansion of an infection that else leads to exacerbated sequestration and death. SEVUPARIN IN PHASE I STUDY: The drug sevuparin was developed from heparin because heparan sulfate and heparin are nearly identical, so the rationale was that sevuparin would act as a decoy receptor during malaria infection. A phase I study was performed in healthy male volunteers and sevuparin was found safe and well tolerated. SEVUPARIN IN PHASE I/II CLINICAL STUDY: A phase I/II clinical study was performed in which sevuparin was administered via short intravenous infusions to malaria patients with uncomplicated malaria who were also receiving atovaquone/proguanil treatment. This was a Phase I/II, randomized, open label, active control, parallel assignment study. Sevuparin was safe and well tolerated in the malaria patients. The mean relative numbers of ring-stage IEs decreased after a single sevuparin infusion and mature parasite IEs appeared transiently in the circulation. The effects observed on numbers of merozoites and throphozoites in the circulation, were detected already one hour after the first sevuparin injection. Here we report the development of a candidate drug named sevuparin that both blocks merozoite invasion and transiently de-sequesters IE in humans with P. falciparum malaria. TRIAL REGISTRATION: ClinicalTrials.gov NCT01442168.


Assuntos
Antimaláricos/farmacologia , Atovaquona/farmacologia , Heparina/análogos & derivados , Malária Falciparum/tratamento farmacológico , Merozoítos/efeitos dos fármacos , Parasitemia/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Proguanil/farmacologia , Administração Oral , Adolescente , Adulto , Idoso , Antimaláricos/sangue , Antimaláricos/farmacocinética , Área Sob a Curva , Atovaquona/sangue , Atovaquona/farmacocinética , Ligação Competitiva , Esquema de Medicação , Combinação de Medicamentos , Quimioterapia Combinada , Eritrócitos/efeitos dos fármacos , Eritrócitos/parasitologia , Feminino , Heparina/sangue , Heparina/farmacocinética , Heparina/farmacologia , Heparitina Sulfato/química , Heparitina Sulfato/metabolismo , Humanos , Infusões Intravenosas , Malária Falciparum/sangue , Malária Falciparum/parasitologia , Masculino , Merozoítos/fisiologia , Pessoa de Meia-Idade , Carga Parasitária , Parasitemia/sangue , Parasitemia/parasitologia , Plasmodium falciparum/fisiologia , Proguanil/sangue , Proguanil/farmacocinética , Índice de Gravidade de Doença
18.
J Antimicrob Chemother ; 72(11): 3051-3058, 2017 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-28961865

RESUMO

Background: The simian malaria parasite Plasmodium knowlesi is now a well-recognized pathogen of humans in South-East Asia. Clinical infections appear adequately treated with existing drug regimens, but the evidence base for this practice remains weak. The availability of P. knowlesi cultures adapted to continuous propagation in human erythrocytes enables specific studies of in vitro susceptibility of the species to antimalarial agents, and could provide a surrogate system for testing investigational compounds against Plasmodium vivax and other non-Plasmodium falciparum infections that cannot currently be propagated in vitro. Objectives: We sought to optimize protocols for in vitro susceptibility testing of P. knowlesi and to contrast outputs with those obtained for P. falciparum under comparable test conditions. Methods: Growth monitoring of P. knowlesi in vitro was by DNA quantification using a SYBR Green fluorescent assay or by colorimetric detection of the lactate dehydrogenase enzyme. For comparison, P. falciparum was tested under conditions identical to those used for P. knowlesi. Results: The SYBR Green I assay proved the most robust format over one (27 h) or two (54 h) P. knowlesi life cycles. Unexpectedly, P. knowlesi displays significantly greater susceptibility to the dihydrofolate reductase inhibitors pyrimethamine, cycloguanil and trimethoprim than does P. falciparum, but is less susceptible to the selective agents blasticidin and DSM1 used in parasite transfections. Inhibitors of dihydroorotate dehydrogenase also demonstrate lower activity against P. knowlesi. Conclusions: The fluorescent assay system validated here identified species-specific P. knowlesi drug susceptibility profiles and can be used for testing investigational compounds for activity against non-P. falciparum malaria.


Assuntos
Antimaláricos/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium knowlesi/efeitos dos fármacos , Colorimetria , Eritrócitos/parasitologia , Fluorescência , Humanos , L-Lactato Desidrogenase/genética , Malária/parasitologia , Compostos Orgânicos , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Testes de Sensibilidade Parasitária , Plasmodium falciparum/enzimologia , Plasmodium falciparum/genética , Plasmodium falciparum/crescimento & desenvolvimento , Plasmodium knowlesi/enzimologia , Plasmodium knowlesi/genética , Plasmodium knowlesi/crescimento & desenvolvimento , Proguanil/farmacologia , Pirimetamina/farmacologia , Sensibilidade e Especificidade , Triazinas/farmacologia
19.
Eur J Med Chem ; 135: 467-478, 2017 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-28477572

RESUMO

We have identified a series of 1-aryl-4,6-diamino-1,2-dihydrotriazines, structurally related to the antimalarial drug cycloguanil, as new inhibitors of influenza A and B virus and respiratory syncytial virus (RSV) via targeting of the host dihydrofolate reductase (DHFR) enzyme. Most analogues proved active against influenza B virus in the low micromolar range, and the best compounds (11, 13, 14 and 16) even reached the sub-micromolar potency of zanamivir (EC50 = 0.060 µM), and markedly exceeded (up to 327 times) the antiviral efficacy of ribavirin. Activity was also observed for two influenza A strains, including a virus with the S31N mutant form of M2 proton channel, which is the most prevalent resistance mutation for amantadine. Importantly, the compounds displayed nanomolar activity against RSV and a superior selectivity index, since the ratio of cytotoxic to antiviral concentration was >10,000 for the three most active compounds 11, 14 and 16 (EC50 ∼0.008 µM), far surpassing the potency and safety profile of the licensed drug ribavirin (EC50 = 5.8 µM, SI > 43).


Assuntos
Antivirais/farmacologia , Antagonistas do Ácido Fólico/farmacologia , Vírus da Influenza A Subtipo H1N1/efeitos dos fármacos , Vírus da Influenza B/efeitos dos fármacos , Proguanil/farmacologia , Vírus Sinciciais Respiratórios/efeitos dos fármacos , Tetra-Hidrofolato Desidrogenase/metabolismo , Triazinas/farmacologia , Antivirais/síntese química , Antivirais/química , Cristalografia por Raios X , Relação Dose-Resposta a Droga , Antagonistas do Ácido Fólico/síntese química , Antagonistas do Ácido Fólico/química , Humanos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , Proguanil/síntese química , Proguanil/química , Relação Estrutura-Atividade , Triazinas/síntese química , Triazinas/química
20.
Sci Rep ; 7: 45871, 2017 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-28361906

RESUMO

The evolutionary relationship between plants and the malarial parasite Plasmodium falciparum is well established and underscored by the P. falciparum apicoplast, an essential chloroplast-like organelle. As a result of this relationship, studies have demonstrated that herbicides active against plants are also active against P. falciparum and thus could act as antimalarial drug leads. Here we show the converse is also true; many antimalarial compounds developed for human use are highly herbicidal. We found that human antimalarial drugs (e.g. sulfadiazine, sulfadoxine, pyrimethamine, cycloguanil) were lethal to the model plant Arabidopsis thaliana at similar concentrations to market herbicides glufosinate and glyphosate. Furthermore, the physicochemical properties of these herbicidal antimalarial compounds were similar to commercially used herbicides. The implications of this finding that many antimalarial compounds are herbicidal proffers two novel applications: (i) using the genetically tractable A. thaliana to reveal mode-of-action for understudied antimalarial drugs, and (ii) co-opting antimalarial compounds as a new source for much needed herbicide lead molecules.


Assuntos
Antimaláricos/farmacologia , Arabidopsis/efeitos dos fármacos , Herbicidas/farmacologia , Arabidopsis/parasitologia , Humanos , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/parasitologia , Proguanil/farmacologia , Pirimetamina/farmacologia , Sulfadiazina/farmacologia , Sulfadoxina/farmacologia , Triazinas/farmacologia
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