RESUMEN
While treatment options for human African trypanosomiasis (HAT) have improved significantly, there is still a need for new drugs with eradication now a realistic possibility. Here, we report the development of 2,4-diaminothiazoles that demonstrate significant potency against Trypanosoma brucei, the causative agent of HAT. Using phenotypic screening to guide structure-activity relationships, potent drug-like inhibitors were developed. Proof of concept was established in an animal model of the hemolymphatic stage of HAT. To treat the meningoencephalitic stage of infection, compounds were optimized for pharmacokinetic properties, including blood-brain barrier penetration. However, in vivo efficacy was not achieved, in part due to compounds evolving from a cytocidal to a cytostatic mechanism of action. Subsequent studies identified a nonessential kinase involved in the inositol biosynthesis pathway as the molecular target of these cytostatic compounds. These studies highlight the need for cytocidal drugs for the treatment of HAT and the importance of static-cidal screening of analogues.
Asunto(s)
Citostáticos , Tripanocidas , Trypanosoma brucei brucei , Tripanosomiasis Africana , Animales , Humanos , Tripanosomiasis Africana/tratamiento farmacológico , Tripanocidas/uso terapéutico , Tripanocidas/farmacocinética , Citostáticos/uso terapéutico , Barrera HematoencefálicaRESUMEN
Visceral leishmaniasis (VL) is a parasitic infection that results in approximately 26â¯000-65â¯000 deaths annually. The available treatments are hampered by issues such as toxicity, variable efficacy, and unsuitable dosing options. The need for new treatments is urgent and led to a collaboration between the Drugs for Neglected Diseases initiative (DNDi), GlaxoSmithKline (GSK), and the University of Dundee. An 8-hydroxynaphthyridine was identified as a start point, and an early compound demonstrated weak efficacy in a mouse model of VL but was hampered by glucuronidation. Efforts to address this led to the development of compounds with improved in vitro profiles, but these were poorly tolerated in vivo. Investigation of the mode of action (MoA) demonstrated that activity was driven by sequestration of divalent metal cations, a mechanism which was likely to drive the poor tolerability. This highlights the importance of investigating MoA and pharmacokinetics at an early stage for phenotypically active series.
Asunto(s)
Antiprotozoarios/química , Antiprotozoarios/farmacología , Diseño de Fármacos , Leishmania/efectos de los fármacos , Naftiridinas/química , Naftiridinas/farmacología , Animales , Concentración 50 Inhibidora , Ratones , Solubilidad , Relación Estructura-Actividad , Agua/químicaRESUMEN
Visceral leishmaniasis (VL) affects millions of people across the world, largely in developing nations. It is fatal if left untreated and the current treatments are inadequate. As such, there is an urgent need for new, improved medicines. In this paper, we describe the identification of a 6-amino-N-(piperidin-4-yl)-1H-pyrazolo[3,4-d]pyrimidine scaffold and its optimization to give compounds which showed efficacy when orally dosed in a mouse model of VL.
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
The leishmaniases are diseases that affect millions of people across the world, in particular visceral leishmaniasis (VL) which is fatal unless treated. Current standard of care for VL suffers from multiple issues and there is a limited pipeline of new candidate drugs. As such, there is a clear unmet medical need to identify new treatments. This paper describes the optimization of a phenotypic hit against Leishmania donovani, the major causative organism of VL. The key challenges were to balance solubility and metabolic stability while maintaining potency. Herein, strategies to address these shortcomings and enhance efficacy are discussed, culminating in the discovery of preclinical development candidate GSK3186899/DDD853651 (1) for VL.
Asunto(s)
Leishmaniasis Visceral/tratamiento farmacológico , Morfolinas/uso terapéutico , Pirazoles/uso terapéutico , Pirimidinas/uso terapéutico , Tripanocidas/uso terapéutico , Animales , Femenino , Células Hep G2 , Humanos , Leishmania donovani/efectos de los fármacos , Masculino , Ratones Endogámicos BALB C , Estructura Molecular , Morfolinas/síntesis química , Morfolinas/toxicidad , Pruebas de Sensibilidad Parasitaria , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/uso terapéutico , Inhibidores de Proteínas Quinasas/toxicidad , Pirazoles/síntesis química , Pirazoles/toxicidad , Pirimidinas/síntesis química , Pirimidinas/toxicidad , Ratas Sprague-Dawley , Relación Estructura-Actividad , Tripanocidas/síntesis química , Tripanocidas/toxicidadRESUMEN
Crystallography has guided the hybridization of two series of Trypanosoma brucei N-myristoyltransferase (NMT) inhibitors, leading to a novel highly selective series. The effect of combining the selectivity enhancing elements from two pharmacophores is shown to be additive and has led to compounds that have greater than 1000-fold selectivity for TbNMT vs HsNMT. Further optimization of the hybrid series has identified compounds with significant trypanocidal activity capable of crossing the blood-brain barrier. By using CF-1 mdr1a deficient mice, we were able to demonstrate full cures in vivo in a mouse model of stage 2 African sleeping sickness. This and previous work provides very strong validation for NMT as a drug target for human African trypanosomiasis in both the peripheral and central nervous system stages of disease.
Asunto(s)
Aciltransferasas/antagonistas & inhibidores , Barrera Hematoencefálica/efectos de los fármacos , Diseño de Fármacos , Tripanocidas/química , Tripanocidas/farmacología , Trypanosoma brucei brucei/efectos de los fármacos , Tripanosomiasis Africana/tratamiento farmacológico , Animales , Supervivencia Celular , Femenino , Humanos , Ratones , Ratones Endogámicos , Modelos Moleculares , Estructura Molecular , Conformación Proteica , Relación Estructura-Actividad , Tripanosomiasis Africana/microbiologíaRESUMEN
Trypanosomatid parasites are the infectious agents causing Chagas disease, visceral and cutaneous leishmaniasis and human African trypanosomiasis. Recent work of others has implicated an aldo-keto reductase (AKR) in the susceptibility and resistance of Trypanosoma cruzi to benznidazole, a drug used to treat Chagas disease. Here, we show that TcAKR and homologues in the related parasites Trypanosoma brucei and Leishmania donovani do not reductively activate monocyclic (benznidazole, nifurtimox and fexinidazole) or bicyclic nitro-drugs such as PA-824. Rather, these enzymes metabolise a variety of toxic ketoaldehydes, such as glyoxal and methylglyoxal, suggesting a role in cellular defence against chemical stress. UPLC-QToF/MS analysis of benznidazole bioactivation by T. cruzi cell lysates confirms previous reports identifying numerous drug metabolites, including a dihydro-dihydroxy intermediate that can dissociate to form N-benzyl-2-guanidinoacetamide and glyoxal, a toxic DNA-glycating and cross-linking agent. Thus, we propose that TcAKR contributes to benznidazole resistance by the removal of toxic glyoxal. In addition, three of the four enzymes studied here display activity as prostaglandin F2α synthases, despite the fact that there are no credible cyclooxygenases in these parasites to account for formation of the precursor PGH2 from arachidonic acid. Our studies suggest that arachidonic acid is first converted non-enzymatically in parasite lysates to (PGH2-like) regioisomers by free radical-mediated peroxidation and that AKRs convert these lipid peroxides into isoprostanes, including prostaglandin F2α and 8-iso-prostaglandin F2α.
Asunto(s)
Aldo-Ceto Reductasas/metabolismo , Dinoprost/análogos & derivados , Dinoprost/metabolismo , Isoprostanos/metabolismo , Leishmania donovani/metabolismo , Proteínas Protozoarias/metabolismo , Piruvaldehído/metabolismo , Trypanosoma brucei brucei/metabolismo , Trypanosoma cruzi/metabolismo , Aldo-Ceto Reductasas/genética , Dinoprost/genética , Isoprostanos/genética , Leishmania donovani/genética , Proteínas Protozoarias/genética , Trypanosoma brucei brucei/genética , Trypanosoma cruzi/genéticaRESUMEN
The lack of information regarding the mechanisms of action (MoA) or specific molecular targets of phenotypically active compounds can prove a barrier to their development as chemotherapeutic agents. Here, we report the results of our orthogonal genetic, molecular, and biochemical studies to determine the MoA of a novel 7-substituted 8-hydroxy-1,6-naphthyridine (8-HNT) series that displays promising activity against Trypanosoma brucei and Leishmania donovani High-throughput loss-of-function genetic screens in T. brucei highlighted two probable zinc transporters associated with resistance to these compounds. These transporters localized to the parasite Golgi apparatus. Directed by these findings, the role of zinc and other divalent cations in the MoA of these compounds was investigated. 8-HNT compounds were found to directly deplete intracellular levels of Zn2+, while the addition of exogenous Zn2+ and Fe2+ reduced the potency of compounds from this series. Detailed biochemical analyses confirmed that 8-HNT compounds bind directly to a number of divalent cations, predominantly Zn2+, Fe2+, and Cu2+, forming 2:1 complexes with one of these cations. Collectively, our studies demonstrate transition metal depletion, due to chelation, as the MoA of the 8-HNT series of compounds. Strategies to improve the selectivity of 8-HNT compounds are discussed.
Asunto(s)
Antiprotozoarios/farmacología , Proteínas de Transporte de Catión/genética , Quelantes/farmacología , Naftiridinas/farmacología , Proteínas Protozoarias/genética , Zinc/metabolismo , Antiprotozoarios/síntesis química , Proteínas de Transporte de Catión/metabolismo , Cationes Bivalentes , Quelantes/síntesis química , Cobre/metabolismo , Expresión Génica , Aparato de Golgi/efectos de los fármacos , Aparato de Golgi/metabolismo , Hierro/metabolismo , Leishmania donovani/efectos de los fármacos , Leishmania donovani/genética , Leishmania donovani/crecimiento & desarrollo , Leishmania donovani/metabolismo , Mutación , Naftiridinas/síntesis química , Pruebas de Sensibilidad Parasitaria , Proteínas Protozoarias/metabolismo , Relación Estructura-Actividad , Trypanosoma brucei brucei/efectos de los fármacos , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/crecimiento & desarrollo , Trypanosoma brucei brucei/metabolismoRESUMEN
N-Myristoyltransferase (NMT) represents a promising drug target within the parasitic protozoa Trypanosoma brucei (T. brucei), the causative agent for human African trypanosomiasis (HAT) or sleeping sickness. We have previously validated T. brucei NMT as a promising druggable target for the treatment of HAT in both stages 1 and 2 of the disease. We report on the use of the previously reported DDD85646 (1) as a starting point for the design of a class of potent, brain penetrant inhibitors of T. brucei NMT.
Asunto(s)
Aciltransferasas/antagonistas & inhibidores , Aminopiridinas/química , Aminopiridinas/farmacología , Sulfonamidas/química , Sulfonamidas/farmacología , Tripanocidas/química , Tripanocidas/farmacología , Trypanosoma brucei brucei/efectos de los fármacos , Trypanosoma brucei brucei/enzimología , Tripanosomiasis Africana/tratamiento farmacológico , Aciltransferasas/metabolismo , Aminopiridinas/síntesis química , Aminopiridinas/farmacocinética , Animales , Encéfalo/metabolismo , Cristalografía por Rayos X , Diseño de Fármacos , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacocinética , Inhibidores Enzimáticos/farmacología , Humanos , Ratones , Sulfonamidas/síntesis química , Sulfonamidas/farmacocinética , Tripanocidas/síntesis química , Tripanocidas/farmacocinética , Tripanosomiasis Africana/metabolismoRESUMEN
Widespread resistance to first-line TB drugs is a major problem that will likely only be resolved through the development of new drugs with novel mechanisms of action. We have used structure-guided methods to develop a lead molecule that targets the thioesterase activity of polyketide synthase Pks13, an essential enzyme that forms mycolic acids, required for the cell wall of Mycobacterium tuberculosis. Our lead, TAM16, is a benzofuran class inhibitor of Pks13 with highly potent in vitro bactericidal activity against drug-susceptible and drug-resistant clinical isolates of M. tuberculosis. In multiple mouse models of TB infection, TAM16 showed in vivo efficacy equal to the first-line TB drug isoniazid, both as a monotherapy and in combination therapy with rifampicin. TAM16 has excellent pharmacological and safety profiles, and the frequency of resistance for TAM16 is â¼100-fold lower than INH, suggesting that it can be developed as a new antitubercular aimed at the acute infection. PAPERCLIP.
Asunto(s)
Antituberculosos/farmacología , Benzofuranos/farmacología , Diseño de Fármacos , Farmacorresistencia Bacteriana , Mycobacterium tuberculosis/efectos de los fármacos , Piperidinas/farmacología , Tuberculosis/microbiología , Animales , Antituberculosos/química , Benzofuranos/química , Benzofuranos/farmacocinética , Línea Celular , Femenino , Ratones , Ratones Endogámicos BALB C , Modelos Moleculares , Piperidinas/química , Piperidinas/farmacocinética , Organismos Libres de Patógenos EspecíficosRESUMEN
Drug discovery pipelines for the "neglected diseases" are now heavily populated with nitroheterocyclic compounds. Recently, the bicyclic nitro-compounds (R)-PA-824, DNDI-VL-2098 and delamanid have been identified as potential candidates for the treatment of visceral leishmaniasis. Using a combination of quantitative proteomics and whole genome sequencing of susceptible and drug-resistant parasites we identified a putative NAD(P)H oxidase as the activating nitroreductase (NTR2). Whole genome sequencing revealed that deletion of a single cytosine in the gene for NTR2 that is likely to result in the expression of a non-functional truncated protein. Susceptibility of leishmania was restored by reintroduction of the wild-type gene into the resistant line, which was accompanied by the ability to metabolise these compounds. Overexpression of NTR2 in wild-type parasites rendered cells hyper-sensitive to bicyclic nitro-compounds, but only marginally to the monocyclic nitro-drugs, nifurtimox and fexinidazole sulfone, known to be activated by a mitochondrial oxygen-insensitive nitroreductase (NTR1). Conversely, a double knockout NTR2 null cell line was completely resistant to bicyclic nitro-compounds and only marginally resistant to nifurtimox. Sensitivity was fully restored on expression of NTR2 in the null background. Thus, NTR2 is necessary and sufficient for activation of these bicyclic nitro-drugs. Recombinant NTR2 was capable of reducing bicyclic nitro-compounds in the same rank order as drug sensitivity in vitro. These findings may aid the future development of better, novel anti-leishmanial drugs. Moreover, the discovery of anti-leishmanial nitro-drugs with independent modes of activation and independent mechanisms of resistance alleviates many of the concerns over the continued development of these compound series.
Asunto(s)
Leishmaniasis Visceral/parasitología , Nitrorreductasas/metabolismo , Proteínas Protozoarias/metabolismo , Tripanocidas/farmacología , Animales , Modelos Animales de Enfermedad , Técnica del Anticuerpo Fluorescente , Técnicas de Silenciamiento del Gen , Espectrometría de Masas , Enfermedades Desatendidas/parasitología , Análisis de Secuencia por Matrices de Oligonucleótidos , Pruebas de Sensibilidad Parasitaria , Reacción en Cadena de la PolimerasaRESUMEN
The antiplasmodial activity, DMPK properties, and efficacy of a series of quinoline-4-carboxamides are described. This series was identified from a phenotypic screen against the blood stage of Plasmodium falciparum (3D7) and displayed moderate potency but with suboptimal physicochemical properties and poor microsomal stability. The screening hit (1, EC50 = 120 nM) was optimized to lead molecules with low nanomolar in vitro potency. Improvement of the pharmacokinetic profile led to several compounds showing excellent oral efficacy in the P. berghei malaria mouse model with ED90 values below 1 mg/kg when dosed orally for 4 days. The favorable potency, selectivity, DMPK properties, and efficacy coupled with a novel mechanism of action, inhibition of translation elongation factor 2 (PfEF2), led to progression of 2 (DDD107498) to preclinical development.
Asunto(s)
Antimaláricos/farmacología , Descubrimiento de Drogas , Malaria/tratamiento farmacológico , Plasmodium falciparum/efectos de los fármacos , Quinolinas/farmacología , Animales , Antimaláricos/síntesis química , Antimaláricos/química , Modelos Animales de Enfermedad , Ratones , Estructura Molecular , Quinolinas/síntesis química , Quinolinas/química , Relación Estructura-ActividadRESUMEN
In this paper we describe the optimization of a phenotypic hit against Plasmodium falciparum, based on a trisubstituted pyrimidine scaffold. This led to compounds with good pharmacokinetics and oral activity in a P. berghei mouse model of malaria. The most promising compound (13) showed a reduction in parasitemia of 96% when dosed at 30 mg/kg orally once a day for 4 days in the P. berghei mouse model of malaria. It also demonstrated a rapid rate of clearance of the erythrocytic stage of P. falciparum in the SCID mouse model with an ED90 of 11.7 mg/kg when dosed orally. Unfortunately, the compound is a potent inhibitor of cytochrome P450 enzymes, probably due to a 4-pyridyl substituent. Nevertheless, this is a lead molecule with a potentially useful antimalarial profile, which could either be further optimized or be used for target hunting.
Asunto(s)
Antimaláricos/química , Antimaláricos/uso terapéutico , Malaria/tratamiento farmacológico , Plasmodium berghei/efectos de los fármacos , Plasmodium falciparum/efectos de los fármacos , Pirimidinas/química , Pirimidinas/uso terapéutico , Animales , Antimaláricos/farmacocinética , Antimaláricos/farmacología , Humanos , Malaria/parasitología , Malaria Falciparum/tratamiento farmacológico , Malaria Falciparum/parasitología , Ratones SCID , Parasitemia/tratamiento farmacológico , Parasitemia/parasitología , Pirimidinas/farmacocinética , Pirimidinas/farmacologíaRESUMEN
There is an urgent requirement for safe, oral and cost-effective drugs for the treatment of visceral leishmaniasis (VL). We report that delamanid (OPC-67683), an approved drug for multi-drug resistant tuberculosis, is a potent inhibitor of Leishmania donovani both in vitro and in vivo. Twice-daily oral dosing of delamanid at 30 mg kg(-1) for 5 days resulted in sterile cures in a mouse model of VL. Treatment with lower doses revealed a U-shaped (hormetic) dose-response curve with greater parasite suppression at 1 mg kg(-1) than at 3 mg kg(-1) (5 or 10 day dosing). Dosing delamanid for 10 days confirmed the hormetic dose-response and improved the efficacy at all doses investigated. Mechanistic studies reveal that delamanid is rapidly metabolised by parasites via an enzyme, distinct from the nitroreductase that activates fexinidazole. Delamanid has the potential to be repurposed as a much-needed oral therapy for VL.
Asunto(s)
Antiprotozoarios/farmacología , Antituberculosos/farmacología , Leishmania donovani/efectos de los fármacos , Leishmaniasis Visceral/tratamiento farmacológico , Nitroimidazoles/farmacología , Oxazoles/farmacología , Administración Oral , Animales , Antiprotozoarios/sangre , Antiprotozoarios/farmacocinética , Antituberculosos/sangre , Antituberculosos/farmacocinética , Biotransformación , Modelos Animales de Enfermedad , Esquema de Medicación , Cálculo de Dosificación de Drogas , Reposicionamiento de Medicamentos , Femenino , Hormesis , Leishmania donovani/crecimiento & desarrollo , Leishmania donovani/patogenicidad , Leishmaniasis Visceral/sangre , Leishmaniasis Visceral/parasitología , Leishmaniasis Visceral/patología , Ratones , Ratones Endogámicos BALB C , Nitroimidazoles/sangre , Nitroimidazoles/farmacocinética , Oxazoles/sangre , Oxazoles/farmacocinética , Pruebas de Sensibilidad Parasitaria , Resultado del TratamientoRESUMEN
The enzyme N-myristoyltransferase (NMT) from Trypanosoma brucei has been validated both chemically and biologically as a potential drug target for human African trypanosomiasis. We previously reported the development of some very potent compounds based around a pyrazole sulfonamide series, derived from a high-throughput screen. Herein we describe work around thiazolidinone and benzomorpholine scaffolds that were also identified in the screen. An X-ray crystal structure of the thiazolidinone hit in Leishmania major NMT showed the compound bound in the previously reported active site, utilising a novel binding mode. This provides potential for further optimisation. The benzomorpholinone was also found to bind in a similar region. Using an X-ray crystallography/structure-based design approach, the benzomorpholinone series was further optimised, increasing activity against T.â brucei NMT by >1000-fold. A series of trypanocidal compounds were identified with suitable in vitro DMPK properties, including CNS exposure for further development. Further work is required to increase selectivity over the human NMT isoform and activity against T.â brucei.
Asunto(s)
Aciltransferasas/antagonistas & inhibidores , Descubrimiento de Drogas , Inhibidores Enzimáticos/farmacología , Bibliotecas de Moléculas Pequeñas/farmacología , Trypanosoma brucei brucei/enzimología , Aciltransferasas/metabolismo , Sitios de Unión/efectos de los fármacos , Cristalografía por Rayos X , Relación Dosis-Respuesta a Droga , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Humanos , Modelos Moleculares , Estructura Molecular , Pruebas de Sensibilidad Parasitaria , Bibliotecas de Moléculas Pequeñas/síntesis química , Bibliotecas de Moléculas Pequeñas/química , Relación Estructura-Actividad , Trypanosoma brucei brucei/efectos de los fármacosRESUMEN
A screen of a focused kinase inhibitor library against Trypanosoma brucei rhodesiense led to the identification of seven series, totaling 121 compounds, which showed >50 % inhibition at 5â µm. Screening of these hits in a T.â b.â brucei proliferation assay highlighted three compounds with a 1H-imidazo[4,5-b]pyrazin-2(3H)-one scaffold that showed sub-micromolar activity and excellent selectivity against the MRC5 cell line. Subsequent rounds of optimisation led to the identification of compounds that exhibited good in vitro drug metabolism and pharmacokinetics (DMPK) properties, although in general this series suffered from poor solubility. A scaffold-hopping exercise led to the identification of a 1H-pyrazolo[3,4-b]pyridine scaffold, which retained potency. A number of examples were assessed in a T.â b.â brucei growth assay, which could differentiate static and cidal action. Compounds from the 1H-imidazo[4,5-b]pyrazin-2(3H)-one series were found to be either static or growth-slowing and not cidal. Compounds with the 1H-pyrazolo[3,4-b]pyridine scaffold were found to be cidal and showed an unusual biphasic nature in this assay, suggesting they act by at least two mechanisms.
Asunto(s)
Descubrimiento de Drogas , Inhibidores de Proteínas Quinasas/farmacología , Proteínas Quinasas/metabolismo , Bibliotecas de Moléculas Pequeñas/farmacología , Trypanosoma brucei rhodesiense/efectos de los fármacos , Línea Celular , Relación Dosis-Respuesta a Droga , Humanos , Estructura Molecular , Pruebas de Sensibilidad Parasitaria , Fenotipo , Inhibidores de Proteínas Quinasas/química , Bibliotecas de Moléculas Pequeñas/química , Relación Estructura-Actividad , Trypanosoma brucei rhodesiense/crecimiento & desarrolloRESUMEN
There is an urgent need for new, brain penetrant small molecules that target the central nervous system second stage of human African trypanosomiasis (HAT). We report that a series of novel indoline-2-carboxamides have been identified as inhibitors of Trypanosoma brucei from screening of a focused protease library against Trypanosoma brucei brucei in culture. We describe the optimization and characterization of this series. Potent antiproliferative activity was observed. The series demonstrated excellent pharmacokinetic properties, full cures in a stage 1 mouse model of HAT, and a partial cure in a stage 2 mouse model of HAT. Lack of tolerability prevented delivery of a fully curative regimen in the stage 2 mouse model and thus further progress of this series.
Asunto(s)
Encéfalo/efectos de los fármacos , Tripanocidas/química , Tripanocidas/farmacología , Trypanosoma brucei brucei/efectos de los fármacos , Tripanosomiasis Africana/tratamiento farmacológico , Animales , Técnicas de Química Sintética , Modelos Animales de Enfermedad , Descubrimiento de Drogas , Evaluación Preclínica de Medicamentos/métodos , Femenino , Indoles/química , Ratones Endogámicos , Estereoisomerismo , Relación Estructura-Actividad , Tripanocidas/farmacocinética , Trypanosoma brucei brucei/crecimiento & desarrollo , Tripanosomiasis Africana/parasitologíaRESUMEN
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.
Asunto(s)
Antimaláricos/farmacología , Regulación de la Expresión Génica/efectos de los fármacos , Malaria/parasitología , Plasmodium/efectos de los fármacos , Plasmodium/metabolismo , Biosíntesis de Proteínas/efectos de los fármacos , Quinolinas/farmacología , Animales , Antimaláricos/administración & dosificación , Antimaláricos/efectos adversos , Antimaláricos/farmacocinética , Descubrimiento de Drogas , Femenino , Estadios del Ciclo de Vida/efectos de los fármacos , Hígado/efectos de los fármacos , Hígado/parasitología , Malaria/tratamiento farmacológico , Masculino , Modelos Moleculares , Factor 2 de Elongación Peptídica/antagonistas & inhibidores , Factor 2 de Elongación Peptídica/metabolismo , Plasmodium/genética , Plasmodium/crecimiento & desarrollo , Plasmodium berghei/efectos de los fármacos , Plasmodium berghei/fisiología , Plasmodium falciparum/efectos de los fármacos , Plasmodium falciparum/metabolismo , Plasmodium vivax/efectos de los fármacos , Plasmodium vivax/metabolismo , Quinolinas/administración & dosificación , Quinolinas/química , Quinolinas/farmacocinéticaRESUMEN
Trypanosoma brucei N-myristoyltransferase (TbNMT) is an attractive therapeutic target for the treatment of human African trypanosomiasis (HAT). From previous studies, we identified pyrazole sulfonamide, DDD85646 (1), a potent inhibitor of TbNMT. Although this compound represents an excellent lead, poor central nervous system (CNS) exposure restricts its use to the hemolymphatic form (stage 1) of the disease. With a clear clinical need for new drug treatments for HAT that address both the hemolymphatic and CNS stages of the disease, a chemistry campaign was initiated to address the shortfalls of this series. This paper describes modifications to the pyrazole sulfonamides which markedly improved blood-brain barrier permeability, achieved by reducing polar surface area and capping the sulfonamide. Moreover, replacing the core aromatic with a flexible linker significantly improved selectivity. This led to the discovery of DDD100097 (40) which demonstrated partial efficacy in a stage 2 (CNS) mouse model of HAT.