RESUMEN
Malaria and cryptosporidiosis, caused by apicomplexan parasites, remain major drivers of global child mortality. New drugs for the treatment of malaria and cryptosporidiosis, in particular, are of high priority; however, there are few chemically validated targets. The natural product cladosporin is active against blood- and liver-stage Plasmodium falciparum and Cryptosporidium parvum in cell-culture studies. Target deconvolution in P. falciparum has shown that cladosporin inhibits lysyl-tRNA synthetase (PfKRS1). Here, we report the identification of a series of selective inhibitors of apicomplexan KRSs. Following a biochemical screen, a small-molecule hit was identified and then optimized by using a structure-based approach, supported by structures of both PfKRS1 and C. parvum KRS (CpKRS). In vivo proof of concept was established in an SCID mouse model of malaria, after oral administration (ED90 = 1.5 mg/kg, once a day for 4 d). Furthermore, we successfully identified an opportunity for pathogen hopping based on the structural homology between PfKRS1 and CpKRS. This series of compounds inhibit CpKRS and C. parvum and Cryptosporidium hominis in culture, and our lead compound shows oral efficacy in two cryptosporidiosis mouse models. X-ray crystallography and molecular dynamics simulations have provided a model to rationalize the selectivity of our compounds for PfKRS1 and CpKRS vs. (human) HsKRS. Our work validates apicomplexan KRSs as promising targets for the development of drugs for malaria and cryptosporidiosis.
Asunto(s)
Criptosporidiosis , Cryptosporidium parvum/enzimología , Inhibidores Enzimáticos/farmacología , Lisina-ARNt Ligasa/antagonistas & inhibidores , Malaria Falciparum , Plasmodium falciparum/enzimología , Proteínas Protozoarias/antagonistas & inhibidores , Animales , Criptosporidiosis/tratamiento farmacológico , Criptosporidiosis/enzimología , Modelos Animales de Enfermedad , Inhibidores Enzimáticos/química , Humanos , Lisina-ARNt Ligasa/metabolismo , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/enzimología , Ratones SCID , Proteínas Protozoarias/metabolismoRESUMEN
Malaria is a devastating parasitic disease caused by parasites from the genus Plasmodium. Therapeutic resistance has been reported against all clinically available antimalarials, threatening our ability to control the disease and therefore there is an ongoing need for the development of novel antimalarials. Towards this goal, we identified the 2-(N-phenyl carboxamide) triazolopyrimidine class from a high throughput screen of the Janssen Jumpstarter library against the asexual stages of the P. falciparum parasite. Here we describe the structure activity relationship of the identified class and the optimisation of asexual stage activity while maintaining selectivity against the human HepG2 cell line. The most potent analogues from this study were shown to exhibit equipotent activity against P. falciparum multidrug resistant strains and P. knowlesi asexual parasites. Asexual stage phenotyping studies determined the triazolopyrimidine class arrests parasites at the trophozoite stage, but it is likely these parasites are still metabolically active until the second asexual cycle, and thus have a moderate to slow onset of action. Non-NADPH dependent degradation of the central carboxamide and low aqueous solubility was observed in in vitro ADME profiling. A significant challenge remains to correct these liabilities for further advancement of the 2-(N-phenyl carboxamide) triazolopyrimidine scaffold as a potential moderate to slow acting partner in a curative or prophylactic antimalarial treatment.
Asunto(s)
Antimaláricos/farmacología , Eritrocitos/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Plasmodium knowlesi/efectos de los fármacos , Purinas/farmacología , Antimaláricos/síntesis química , Antimaláricos/química , Relación Dosis-Respuesta a Droga , Eritrocitos/parasitología , Humanos , Estructura Molecular , Pruebas de Sensibilidad Parasitaria , Purinas/síntesis química , Purinas/química , Relación Estructura-ActividadRESUMEN
A series of 4-amino 2-anilinoquinazolines optimized for activity against the most lethal malaria parasite of humans, Plasmodium falciparum, was evaluated for activity against other human Plasmodium parasites and related apicomplexans that infect humans and animals. Four of the most promising compounds from the 4-amino 2-anilinoquinazoline series were equally as effective against the asexual blood stages of the zoonotic P. knowlesi, suggesting that they could also be effective against the closely related P. vivax, another important human pathogen. The 2-anilinoquinazoline compounds were also potent against an array of P. falciparum parasites resistant to clinically available antimalarial compounds, although slightly less so than against the drug-sensitive 3D7 parasite line. The apicomplexan parasites Toxoplasma gondii, Babesia bovis, and Cryptosporidium parvum were less sensitive to the 2-anilinoquinazoline series with a 50% effective concentration generally in the low micromolar range, suggesting that the yet to be discovered target of these compounds is absent or highly divergent in non-Plasmodium parasites. The 2-anilinoquinazoline compounds act as rapidly as chloroquine in vitro and when tested in rodents displayed a half-life that contributed to the compound's capacity to clear P. falciparum blood stages in a humanized mouse model. At a dose of 50 mg/kg of body weight, adverse effects to the humanized mice were noted, and evaluation against a panel of experimental high-risk off targets indicated some potential off-target activity. Further optimization of the 2-anilinoquinazoline antimalarial class will concentrate on improving in vivo efficacy and addressing adverse risk.
Asunto(s)
Compuestos de Anilina/farmacología , Antiparasitarios/farmacología , Babesia bovis/efectos de los fármacos , Cryptosporidium parvum/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Quinazolinas/farmacología , Toxoplasma/efectos de los fármacos , Animales , Antimaláricos/farmacología , Línea Celular , Cloroquina/farmacología , Modelos Animales de Enfermedad , Humanos , Ratones , Ratones Endogámicos NOD , Ratones SCID , Pruebas de Sensibilidad Parasitaria , Ratas , Ratas Sprague-DawleyRESUMEN
The discovery and development of new antimalarial drugs are becoming imperative because of the spread of resistance to current clinical treatments. The lack of robustly validated antimalarial targets and the difficulties with the building in of whole-cell activity in screening hits are hampering target-based approaches. However, phenotypic screens of structurally diverse molecule libraries are offering new opportunities for the identification of novel antimalarials. Several methodologies can be used to determine the whole-cell in vitro potencies of antimalarial hits. The [(3)H]hypoxanthine incorporation assay is considered the "gold standard" assay for measurement of the activity of antimalarial compounds against intraerythrocytic forms of Plasmodium falciparum However, the method has important limitations, as the assay is not amenable for high-throughput screening since it remains associated with the 96-well plate format. We have overcome this drawback by adapting the [(3)H]hypoxanthine incorporation method to a 384-well high-density format by coupling a homogeneous scintillation proximity assay (SPA) and thus eliminating the limiting filtration step. This SPA has been validated using a diverse set of 1,000 molecules, including both a representative set from the Tres Cantos Antimalarial Set (TCAMS) of compounds and molecules inactive against whole cells. The results were compared with those from the P. falciparum lactate dehydrogenase whole-cell assay, another method that is well established as a surrogate for parasite growth and is amenable for high-throughput screening. The results obtained demonstrate that the SPA-based [(3)H]hypoxanthine incorporation assay is a suitable design that is adaptable to high-throughput antimalarial drug screening and that maintains the features, robustness, and reliability of the standard filtration hypoxanthine incorporation method.
Asunto(s)
Antimaláricos/farmacología , Evaluación Preclínica de Medicamentos/métodos , Plasmodium falciparum/crecimiento & desarrollo , Hipoxantina/análisis , Hipoxantina/metabolismo , Concentración 50 Inhibidora , Plasmodium falciparum/efectos de los fármacos , Reproducibilidad de los Resultados , TritioRESUMEN
Malaria is a devastating infection caused by protozoa of the genus Plasmodium. Drug resistance is widespread, no new chemical class of antimalarials has been introduced into clinical practice since 1996 and there is a recent rise of parasite strains with reduced sensitivity to the newest drugs. We screened nearly 2 million compounds in GlaxoSmithKline's chemical library for inhibitors of P. falciparum, of which 13,533 were confirmed to inhibit parasite growth by at least 80% at 2 microM concentration. More than 8,000 also showed potent activity against the multidrug resistant strain Dd2. Most (82%) compounds originate from internal company projects and are new to the malaria community. Analyses using historic assay data suggest several novel mechanisms of antimalarial action, such as inhibition of protein kinases and host-pathogen interaction related targets. Chemical structures and associated data are hereby made public to encourage additional drug lead identification efforts and further research into this disease.
Asunto(s)
Antimaláricos/análisis , Antimaláricos/farmacología , Descubrimiento de Drogas , Malaria Falciparum/tratamiento farmacológico , Plasmodium falciparum/efectos de los fármacos , Bibliotecas de Moléculas Pequeñas/análisis , Bibliotecas de Moléculas Pequeñas/farmacología , Animales , Antimaláricos/química , Antimaláricos/toxicidad , Línea Celular Tumoral , Resistencia a Múltiples Medicamentos/efectos de los fármacos , Humanos , Malaria Falciparum/parasitología , Modelos Biológicos , Filogenia , Plasmodium falciparum/enzimología , Plasmodium falciparum/genética , Plasmodium falciparum/crecimiento & desarrollo , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/toxicidadRESUMEN
Current antimalarials are under continuous threat due to the relentless development of drug resistance by malaria parasites. We previously reported promising in vitro parasite-killing activity with the histone methyltransferase inhibitor BIX-01294 and its analogue TM2-115. Here, we further characterize these diaminoquinazolines for in vitro and in vivo efficacy and pharmacokinetic properties to prioritize and direct compound development. BIX-01294 and TM2-115 displayed potent in vitro activity, with 50% inhibitory concentrations (IC50s) of <50 nM against drug-sensitive laboratory strains and multidrug-resistant field isolates, including artemisinin-refractory Plasmodium falciparum isolates. Activities against ex vivo clinical isolates of both P. falciparum and Plasmodium vivax were similar, with potencies of 300 to 400 nM. Sexual-stage gametocyte inhibition occurs at micromolar levels; however, mature gametocyte progression to gamete formation is inhibited at submicromolar concentrations. Parasite reduction ratio analysis confirms a high asexual-stage rate of killing. Both compounds examined displayed oral efficacy in in vivo mouse models of Plasmodium berghei and P. falciparum infection. The discovery of a rapid and broadly acting antimalarial compound class targeting blood stage infection, including transmission stage parasites, and effective against multiple malaria-causing species reveals the diaminoquinazoline scaffold to be a very promising lead for development into greatly needed novel therapies to control malaria.
Asunto(s)
Antimaláricos/uso terapéutico , Azepinas/uso terapéutico , N-Metiltransferasa de Histona-Lisina/antagonistas & inhibidores , Malaria/tratamiento farmacológico , Quinazolinas/uso terapéutico , Animales , Antimaláricos/química , Azepinas/química , Femenino , Células Hep G2 , Histona Metiltransferasas , Humanos , Malaria Falciparum/tratamiento farmacológico , Ratones , Ratones SCID , Plasmodium berghei/efectos de los fármacos , Plasmodium berghei/patogenicidad , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/patogenicidad , Quinazolinas/químicaRESUMEN
A series of new boron-containing benzoxaborole compounds was designed and synthesized for a continuing structure-activity relationship (SAR) investigation to assess the antimalarial activity changes derived from side-chain structural variation, substituent modification on the benzene ring and removal of boron from five-membered oxaborole ring. This SAR study demonstrated that boron is required for the antimalarial activity, and discovered that three fluoro-substituted 7-(2-carboxyethyl)-1,3-dihydro-1-hydroxy-2,1-benzoxaboroles (9, 14 and 20) have excellent potencies (IC(50) 0.026-0.209 µM) against Plasmodium falciparum.
Asunto(s)
Antimaláricos/síntesis química , Antimaláricos/farmacología , Compuestos de Boro/síntesis química , Compuestos de Boro/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/síntesis química , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Flúor/química , Plasmodium falciparum/efectos de los fármacos , Antimaláricos/química , Antimaláricos/toxicidad , Compuestos de Boro/química , Compuestos de Boro/toxicidad , Compuestos Bicíclicos Heterocíclicos con Puentes/química , Compuestos Bicíclicos Heterocíclicos con Puentes/toxicidad , Supervivencia Celular/efectos de los fármacos , Células HeLa , Humanos , Concentración 50 Inhibidora , Células Jurkat , Estructura Molecular , Relación Estructura-ActividadRESUMEN
Drug resistance and a dire lack of transmission-blocking antimalarials hamper malaria elimination. Here, we present the pantothenamide MMV693183 as a first-in-class acetyl-CoA synthetase (AcAS) inhibitor to enter preclinical development. Our studies demonstrate attractive drug-like properties and in vivo efficacy in a humanized mouse model of Plasmodium falciparum infection. The compound shows single digit nanomolar in vitro activity against P. falciparum and P. vivax clinical isolates, and potently blocks P. falciparum transmission to Anopheles mosquitoes. Genetic and biochemical studies identify AcAS as the target of the MMV693183-derived antimetabolite, CoA-MMV693183. Pharmacokinetic-pharmacodynamic modelling predict that a single 30 mg oral dose is sufficient to cure a malaria infection in humans. Toxicology studies in rats indicate a > 30-fold safety margin in relation to the predicted human efficacious exposure. In conclusion, MMV693183 represents a promising candidate for further (pre)clinical development with a novel mode of action for treatment of malaria and blocking transmission.
Asunto(s)
Antimaláricos , Antagonistas del Ácido Fólico , Malaria Falciparum , Malaria Vivax , Malaria , Animales , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Malaria/tratamiento farmacológico , Malaria Falciparum/tratamiento farmacológico , Malaria Vivax/tratamiento farmacológico , Ratones , Ácido Pantoténico/análogos & derivados , Plasmodium falciparum/genética , RatasRESUMEN
Malaria is one of the deadliest infectious diseases in the world, with the eukaryotic parasite Plasmodium falciparum causing the most severe form of the disease. Discovery of new classes of antimalarial drugs has become an urgent task to counteract the increasing problem of drug resistance. Screening directly for compounds able to inhibit parasite growth in vitro is one of the main approaches the malaria research community is now pursuing for the identification of novel antimalarial drug leads. Very recently, thousands of compounds with potent activity against the parasite P. falciparum have been identified and information about their molecular descriptors, antiplasmodial potency, and cytotoxicity is publicly available. Now the challenges are how to identify the most promising chemotypes for further development and how best to progress these compounds through a lead optimization program to generate antimalarial drug candidates. We report here the first chemical series to be characterized from one of those screenings, a completely novel chemical class with the generic name cyclopropyl carboxamides that has never before been described as having antimalarial or other pharmacological activities. Cyclopropyl carboxamides are potent inhibitors of drug-sensitive and -resistant strains of P. falciparum in vitro and show in vivo oral efficacy in malaria mouse models. In the present work, we describe the biological characterization of this chemical family, showing that inhibition of their still unknown target has very favorable pharmacological consequences but the compounds themselves seem to select for resistance at a high frequency.
Asunto(s)
Amidas , Antimaláricos , Malaria Falciparum/tratamiento farmacológico , Plasmodium falciparum/efectos de los fármacos , Amidas/química , Amidas/farmacología , Amidas/uso terapéutico , Amidas/toxicidad , Animales , Antimaláricos/química , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Antimaláricos/toxicidad , Línea Celular , Eritrocitos/parasitología , Femenino , Humanos , Malaria Falciparum/parasitología , Ratones , Ratones Endogámicos NOD , Ratones SCID , Pruebas de Sensibilidad Parasitaria , Plasmodium falciparum/crecimiento & desarrollo , Relación Estructura-Actividad , Resultado del TratamientoRESUMEN
A phenotypic high-throughput screen allowed discovery of quinazolinone-2-carboxamide derivatives as a novel antimalarial scaffold. Structure-activity relationship studies led to identification of a potent inhibitor 19f, 95-fold more potent than the original hit compound, active against laboratory-resistant strains of malaria. Profiling of 19f suggested a fast in vitro killing profile. In vivo activity in a murine model of human malaria in a dose-dependent manner constitutes a concomitant benefit.
Asunto(s)
Antimaláricos/química , Antimaláricos/farmacología , Malaria Falciparum/tratamiento farmacológico , Quinazolinonas/farmacología , Administración Oral , Animales , Humanos , Ratones , Estructura Molecular , Plasmodium falciparum/efectos de los fármacos , Quinazolinonas/química , Relación Estructura-ActividadRESUMEN
Prolyl-tRNA synthetase (PRS) is a clinically validated antimalarial target. Screening of a set of PRS ATP-site binders, initially designed for human indications, led to identification of 1-(pyridin-4-yl)pyrrolidin-2-one derivatives representing a novel antimalarial scaffold. Evidence designates cytoplasmic PRS as the drug target. The frontrunner 1 and its active enantiomer 1-S exhibited low-double-digit nanomolar activity against resistant Plasmodium falciparum (Pf) laboratory strains and development of liver schizonts. No cross-resistance with strains resistant to other known antimalarials was noted. In addition, a similar level of growth inhibition was observed against clinical field isolates of Pf and P. vivax. The slow killing profile and the relative high propensity to develop resistance in vitro (minimum inoculum resistance of 8 × 105 parasites at a selection pressure of 3 × IC50) constitute unfavorable features for treatment of malaria. However, potent blood stage and antischizontal activity are compelling for causal prophylaxis which does not require fast onset of action. Achieving sufficient on-target selectivity appears to be particularly challenging and should be the primary focus during the next steps of optimization of this chemical series. Encouraging preliminary off-target profile and oral efficacy in a humanized murine model of Pf malaria allowed us to conclude that 1-(pyridin-4-yl)pyrrolidin-2-one derivatives represent a promising starting point for the identification of novel antimalarial prophylactic agents that selectively target Plasmodium PRS.
Asunto(s)
Aminoacil-ARNt Sintetasas , Antimaláricos , Malaria Falciparum , Malaria , Animales , Antimaláricos/farmacología , Humanos , Malaria/tratamiento farmacológico , Malaria Falciparum/tratamiento farmacológico , Ratones , Plasmodium falciparumRESUMEN
The early stages of the COVID-19 pandemic presented the characteristics of a traumatic event that could trigger post-traumatic stress disorder. Emergency Medical Services workers are already a high-risk group due to their professional development. The research project aimed to analyse the impact of the COVID-19 pandemic on EMS professionals in terms of their mental health. For this purpose, we present a descriptive crosssectional study with survey methodology. A total of 317 EMS workers (doctors, nurses, and emergency medical technicians) were recruited voluntarily. Psychological distress, post-traumatic stress disorder, and insomnia were assessed. The instruments were the General Health Questionnaire-12 (GHQ-12), the Davidson Trauma Scale (DTS-8), and the Athens Insomnia Scale (AIS-8). We found that 36% of respondents had psychological distress, 30.9% potentially had PTSD, and 60.9% experienced insomnia. Years of work experience were found to be positively correlated, albeit with low effect, with the PTSD score (r = 0.133). Finally, it can be stated that the COVID-19 pandemic has been a traumatic event for EMS workers. The number of professionals presenting psychological distress, possible PTSD, or insomnia increased dramatically during the early phases of the pandemic. This study highlights the need for mental health disorder prevention programmes for EMS workers in the face of a pandemic.
Asunto(s)
COVID-19 , Trastornos por Estrés Postraumático , Humanos , Pandemias , SARS-CoV-2 , España/epidemiología , Trastornos por Estrés Postraumático/epidemiologíaRESUMEN
The emergence and spread of Plasmodium falciparum resistance to first-line antimalarials creates an imperative to identify and develop potent preclinical candidates with distinct modes of action. Here, we report the identification of MMV688533, an acylguanidine that was developed following a whole-cell screen with compounds known to hit high-value targets in human cells. MMV688533 displays fast parasite clearance in vitro and is not cross-resistant with known antimalarials. In a P. falciparum NSG mouse model, MMV688533 displays a long-lasting pharmacokinetic profile and excellent safety. Selection studies reveal a low propensity for resistance, with modest loss of potency mediated by point mutations in PfACG1 and PfEHD. These proteins are implicated in intracellular trafficking, lipid utilization, and endocytosis, suggesting interference with these pathways as a potential mode of action. This preclinical candidate may offer the potential for a single low-dose cure for malaria.
Asunto(s)
Antimaláricos , Malaria Falciparum , Malaria , Parásitos , Animales , Antimaláricos/farmacología , Antimaláricos/uso terapéutico , Endocitosis , Malaria/tratamiento farmacológico , Malaria Falciparum/tratamiento farmacológico , Plasmodium falciparumRESUMEN
Malaria is a major tropical disease where important needs are to mitigate symptoms and to prevent the establishment of infection. Cyclopeptides containing N-methyl amino acids with in vitro activity against erythrocytic forms as well as liver stage are presented. The synthesis, parasitological characterization, physicochemical properties, in vivo evaluation, and mice pharmacokinetics are described.
RESUMEN
Herein we describe the optimization of a phenotypic hit against Plasmodium falciparum based on an aminoacetamide scaffold. This led to N-(3-chloro-4-fluorophenyl)-2-methyl-2-{[4-methyl-3-(morpholinosulfonyl)phenyl]amino}propanamide (compound 28) with low-nanomolar activity against the intraerythrocytic stages of the malaria parasite, and which was found to be inactive in a mammalian cell counter-screen up to 25â µm. Inhibition of gametes in the dual gamete activation assay suggests that this family of compounds may also have transmission blocking capabilities. Whilst we were unable to optimize the aqueous solubility and microsomal stability to a point at which the aminoacetamides would be suitable for inâ vivo pharmacokinetic and efficacy studies, compound 28 displayed excellent antimalarial potency and selectivity; it could therefore serve as a suitable chemical tool for drug target identification.
Asunto(s)
Acetamidas/farmacología , Antimaláricos/farmacología , Acetamidas/síntesis química , Acetamidas/farmacocinética , Animales , Antimaláricos/síntesis química , Antimaláricos/farmacocinética , Humanos , Ratones , Microsomas Hepáticos/metabolismo , Estructura Molecular , Pruebas de Sensibilidad Parasitaria , Plasmodium berghei/efectos de los fármacos , Plasmodium cynomolgi/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Relación Estructura-ActividadRESUMEN
Carboxamide pyrazinyloxy benzoxaboroles were investigated with the goal to identify a molecule with satisfactory antimalarial activity, physicochemical properties, pharmacokinetic profile, in vivo efficacy, and safety profile. This optimization effort discovered 46, which met our target candidate profile. Compound 46 had excellent activity against cultured Plasmodium falciparum, and in vivo against P. falciparum and P. berghei in infected mice. It exhibited good PK properties in mice, rats, and dogs. It was highly active against the other 11 P. falciparum strains, which are mostly resistant to chloroquine and pyrimethamine. The rapid parasite in vitro reduction and in vivo parasite clearance profile of 46 were similar to those of artemisinin and chloroquine, two rapid-acting antimalarials. It was nongenotoxic in an Ames assay, an in vitro micronucleus assay, and an in vivo rat micronucleus assay when dosed orally up to 2000 mg/kg. The combined properties of this novel benzoxaborole support its progression to preclinical development.
Asunto(s)
Antimaláricos/química , Antimaláricos/farmacología , Compuestos de Boro/química , Compuestos de Boro/farmacología , Malaria/tratamiento farmacológico , Plasmodium berghei/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Amidas/química , Amidas/farmacocinética , Amidas/farmacología , Amidas/uso terapéutico , Animales , Antimaláricos/farmacocinética , Antimaláricos/uso terapéutico , Compuestos de Boro/farmacocinética , Compuestos de Boro/uso terapéutico , Perros , Femenino , Humanos , Malaria Falciparum/tratamiento farmacológico , Masculino , Ratones , Ratas , Ratas Sprague-Dawley , Relación Estructura-ActividadRESUMEN
Benzoxaboroles are effective against bacterial, fungal and protozoan pathogens. We report potent activity of the benzoxaborole AN3661 against Plasmodium falciparum laboratory-adapted strains (mean IC50 32 nM), Ugandan field isolates (mean ex vivo IC50 64 nM), and murine P. berghei and P. falciparum infections (day 4 ED90 0.34 and 0.57 mg kg-1, respectively). Multiple P. falciparum lines selected in vitro for resistance to AN3661 harboured point mutations in pfcpsf3, which encodes a homologue of mammalian cleavage and polyadenylation specificity factor subunit 3 (CPSF-73 or CPSF3). CRISPR-Cas9-mediated introduction of pfcpsf3 mutations into parental lines recapitulated AN3661 resistance. PfCPSF3 homology models placed these mutations in the active site, where AN3661 is predicted to bind. Transcripts for three trophozoite-expressed genes were lost in AN3661-treated trophozoites, which was not observed in parasites selected or engineered for AN3661 resistance. Our results identify the pre-mRNA processing factor PfCPSF3 as a promising antimalarial drug target.
Asunto(s)
Antimaláricos/farmacología , Compuestos de Boro/farmacología , Factor de Especificidad de Desdoblamiento y Poliadenilación/química , Plasmodium falciparum/efectos de los fármacos , Proteínas Protozoarias/química , ARN Mensajero/genética , Secuencia de Aminoácidos , Animales , Antimaláricos/síntesis química , Compuestos de Boro/síntesis química , Sistemas CRISPR-Cas , Dominio Catalítico , Factor de Especificidad de Desdoblamiento y Poliadenilación/antagonistas & inhibidores , Factor de Especificidad de Desdoblamiento y Poliadenilación/genética , Factor de Especificidad de Desdoblamiento y Poliadenilación/metabolismo , Resistencia a Medicamentos/genética , Eritrocitos/efectos de los fármacos , Eritrocitos/parasitología , Edición Génica/métodos , Humanos , Malaria/tratamiento farmacológico , Malaria/parasitología , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/parasitología , Ratones , Simulación del Acoplamiento Molecular , Mutación , Plasmodium berghei/efectos de los fármacos , Plasmodium berghei/genética , Plasmodium berghei/crecimiento & desarrollo , Plasmodium berghei/metabolismo , Plasmodium falciparum/genética , Plasmodium falciparum/crecimiento & desarrollo , Plasmodium falciparum/metabolismo , Unión Proteica , Dominios y Motivos de Interacción de Proteínas , Estructura Secundaria de Proteína , Proteínas Protozoarias/antagonistas & inhibidores , Proteínas Protozoarias/genética , Proteínas Protozoarias/metabolismo , ARN Mensajero/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Trofozoítos/efectos de los fármacos , Trofozoítos/genética , Trofozoítos/crecimiento & desarrollo , Trofozoítos/metabolismoRESUMEN
To combat drug resistance, new chemical entities are urgently required for use in next generation anti-malarial combinations. We report here the results of a medicinal chemistry programme focused on an imidazopyridine series targeting the Plasmodium falciparum cyclic GMP-dependent protein kinase (PfPKG). The most potent compound (ML10) has an IC50 of 160 pM in a PfPKG kinase assay and inhibits P. falciparum blood stage proliferation in vitro with an EC50 of 2.1 nM. Oral dosing renders blood stage parasitaemia undetectable in vivo using a P. falciparum SCID mouse model. The series targets both merozoite egress and erythrocyte invasion, but crucially, also blocks transmission of mature P. falciparum gametocytes to Anopheles stephensi mosquitoes. A co-crystal structure of PvPKG bound to ML10, reveals intimate molecular contacts that explain the high levels of potency and selectivity we have measured. The properties of this series warrant consideration for further development to produce an antimalarial drug.Protein kinases are promising drug targets for treatment of malaria. Here, starting with a medicinal chemistry approach, Baker et al. generate an imidazopyridine that selectively targets Plasmodium falciparum PKG, inhibits blood stage parasite growth in vitro and in mice and blocks transmission to mosquitoes.
Asunto(s)
Proteínas Quinasas Dependientes de GMP Cíclico/antagonistas & inhibidores , Imidazoles/uso terapéutico , Malaria/enzimología , Malaria/transmisión , Piridinas/uso terapéutico , Animales , Línea Celular , Cristalografía por Rayos X , Culicidae , Proteínas Quinasas Dependientes de GMP Cíclico/química , Proteínas Quinasas Dependientes de GMP Cíclico/metabolismo , Modelos Animales de Enfermedad , Femenino , Humanos , Imidazoles/farmacología , Estadios del Ciclo de Vida/efectos de los fármacos , Malaria/tratamiento farmacológico , Ratones Endogámicos BALB C , Modelos Moleculares , Plasmodium chabaudi/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/crecimiento & desarrollo , Inhibidores de Proteínas Quinasas/farmacología , Inhibidores de Proteínas Quinasas/uso terapéutico , Piridinas/farmacología , Resultado del TratamientoRESUMEN
A series of 6-hetaryloxy benzoxaborole compounds was designed and synthesized for a structure-activity relationship (SAR) investigation to assess the changes in antimalarial activity which result from 6-aryloxy structural variation, substituent modification on the pyrazine ring, and optimization of the side chain ester group. This SAR study discovered highly potent 6-(2-(alkoxycarbonyl)pyrazinyl-5-oxy)-1,3-dihydro-1-hydroxy-2,1-benzoxaboroles (9, 27-34) with IC50s = 0.2-22 nM against cultured Plasmodium falciparum W2 and 3D7 strains. Compound 9 also demonstrated excellent in vivo efficacy against P. berghei in infected mice (ED90 = 7.0 mg/kg).
Asunto(s)
Antimaláricos/química , Antimaláricos/farmacología , Compuestos de Boro/química , Compuestos de Boro/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/química , Malaria Falciparum/tratamiento farmacológico , Microsomas Hepáticos/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Pirazinas/química , Pirazinas/farmacología , Animales , Supervivencia Celular/efectos de los fármacos , Femenino , Humanos , Células Jurkat , Malaria Falciparum/parasitología , Ratones , Modelos Moleculares , Estructura Molecular , Pruebas de Sensibilidad Parasitaria , Relación Estructura-ActividadRESUMEN
Malaria continues to be a major global health problem, being particularly devastating in the African population under the age of five. Artemisinin-based combination therapies (ACTs) are the first-line treatment recommended by the WHO to treat Plasmodium falciparum malaria, but clinical resistance against them has already been reported. As a consequence, novel chemotypes are urgently needed. Herein we report a novel, in vivo active, fast-acting antimalarial chemotype based on a benzimidazole core. This discovery is the result of a medicinal chemistry plan focused on improving the developability profile of an antichlamydial chemical class previously reported by our group.