RESUMEN
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
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
Recent development of benzoxaborole-based chemistry gave rise to a collection of compounds with great potential in targeting diverse infectious diseases, including human African Trypanosomiasis (HAT), a devastating neglected tropical disease. However, further medicinal development is largely restricted by a lack of insight into mechanism of action (MoA) in pathogenic kinetoplastids. We adopted a multidisciplinary approach, combining a high-throughput forward genetic screen with functional group focused chemical biological, structural biology and biochemical analyses, to tackle the complex MoAs of benzoxaboroles in Trypanosoma brucei. We describe an oxidative enzymatic pathway composed of host semicarbazide-sensitive amine oxidase and a trypanosomal aldehyde dehydrogenase TbALDH3. Two sequential reactions through this pathway serve as the key underlying mechanism for activating a series of 4-aminomethylphenoxy-benzoxaboroles as potent trypanocides; the methylamine parental compounds as pro-drugs are transformed first into intermediate aldehyde metabolites, and further into the carboxylate metabolites as effective forms. Moreover, comparative biochemical and crystallographic analyses elucidated the catalytic specificity of TbALDH3 towards the benzaldehyde benzoxaborole metabolites as xenogeneic substrates. Overall, this work proposes a novel drug activation mechanism dependent on both host and parasite metabolism of primary amine containing molecules, which contributes a new perspective to our understanding of the benzoxaborole MoA, and could be further exploited to improve the therapeutic index of antimicrobial compounds.
Asunto(s)
Aldehído Deshidrogenasa/metabolismo , Amina Oxidasa (conteniendo Cobre)/metabolismo , Compuestos de Boro/metabolismo , Modelos Biológicos , Profármacos/metabolismo , Tripanocidas/metabolismo , Trypanosoma brucei brucei/enzimología , Activación Metabólica , Aldehído Deshidrogenasa/antagonistas & inhibidores , Aldehído Deshidrogenasa/química , Aldehído Deshidrogenasa/genética , Aldehído Oxidorreductasas/antagonistas & inhibidores , Aldehído Oxidorreductasas/química , Aldehído Oxidorreductasas/genética , Aldehído Oxidorreductasas/metabolismo , Amina Oxidasa (conteniendo Cobre)/antagonistas & inhibidores , Amina Oxidasa (conteniendo Cobre)/química , Amina Oxidasa (conteniendo Cobre)/genética , Sustitución de Aminoácidos , Animales , Compuestos de Boro/química , Compuestos de Boro/farmacología , Resistencia a Medicamentos , Ensayos Analíticos de Alto Rendimiento , Humanos , Estructura Molecular , Mutación , Filogenia , Profármacos/química , Profármacos/farmacología , Dominios y Motivos de Interacción de Proteínas , Interferencia de ARN , Ratas , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Relación Estructura-Actividad , Tripanocidas/química , Tripanocidas/farmacología , Trypanosoma brucei brucei/efectos de los fármacos , Trypanosoma brucei brucei/fisiologíaRESUMEN
Aspirin, or acetylsalicylic acid is widely used to control pain, inflammation and fever. Important to this function is its ability to irreversibly acetylate cyclooxygenases at active site serines. Aspirin has the potential to acetylate other amino acid side-chains, leading to the possibility that aspirin-mediated lysine acetylation could explain some of its as-yet unexplained drug actions or side-effects. Using isotopically labeled aspirin-d3, in combination with acetylated lysine purification and LC-MS/MS, we identified over 12000 sites of lysine acetylation from cultured human cells. Although aspirin amplifies endogenous acetylation signals at the majority of detectable endogenous sites, cells tolerate aspirin mediated acetylation very well unless cellular deacetylases are inhibited. Although most endogenous acetylations are amplified by orders of magnitude, lysine acetylation site occupancies remain very low even after high doses of aspirin. This work shows that while aspirin has enormous potential to alter protein function, in the majority of cases aspirin-mediated acetylations do not accumulate to levels likely to elicit biological effects. These findings are consistent with an emerging model for cellular acetylation whereby stoichiometry correlates with biological relevance, and deacetylases act to minimize the biological consequences of nonspecific chemical acetylations.
Asunto(s)
Aspirina/farmacología , Lisina/análisis , Proteoma/química , Proteómica/métodos , Acetilación , Sitios de Unión , Cromatografía Liquida , Células HeLa , Histona Desacetilasas/metabolismo , Humanos , Marcaje Isotópico , Lisina/química , Lisina/efectos de los fármacos , Espectrometría de Masas en TándemRESUMEN
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 oral S1PR1 agonist ponesimod demonstrated substantial efficacy in a phase II clinical trial of psoriasis. Unfortunately, systemic side effects were observed, which included lymphopenia and transient bradycardia. We sought to develop a topical soft-drug S1PR1 agonist with an improved therapeutic index. By modifying ponesimod, we discovered an ester series of S1PR agonists. To increase metabolic instability in plasma we synthesised esters described as specific substrates for paraoxonase and butyrylcholinesterases, esterases present in human plasma.
Asunto(s)
Descubrimiento de Drogas , Receptores de Lisoesfingolípidos/efectos de los fármacos , Tiazoles/farmacología , Administración Tópica , Arildialquilfosfatasa/sangre , Cromatografía Líquida de Alta Presión , Cromatografía de Fase Inversa , Esterasas/sangre , Esterasas/metabolismo , Humanos , Piel/enzimología , Solubilidad , Receptores de Esfingosina-1-Fosfato , Relación Estructura-Actividad , Tiazoles/administración & dosificaciónRESUMEN
Maturation and translation of mRNA in eukaryotes requires the addition of the 7-methylguanosine cap. In vertebrates, the cap methyltransferase, RNA guanine-7 methyltransferase (RNMT), has an activating subunit, RNMT-Activating Miniprotein (RAM). Here we report the first crystal structure of the human RNMT in complex with the activation domain of RAM. A relatively unstructured and negatively charged RAM binds to a positively charged surface groove on RNMT, distal to the active site. This results in stabilisation of a RNMT lobe structure which co-evolved with RAM and is required for RAM binding. Structure-guided mutagenesis and molecular dynamics simulations reveal that RAM stabilises the structure and positioning of the RNMT lobe and the adjacent α-helix hinge, resulting in optimal positioning of helix A which contacts substrates in the active site. Using biophysical and biochemical approaches, we observe that RAM increases the recruitment of the methyl donor, AdoMet (S-adenosyl methionine), to RNMT. Thus we report the mechanism by which RAM allosterically activates RNMT, allowing it to function as a molecular rheostat for mRNA cap methylation.
Asunto(s)
Metiltransferasas/química , Metiltransferasas/metabolismo , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/metabolismo , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Sitios de Unión , Catálisis , Dominio Catalítico , Activación Enzimática , Humanos , Espectroscopía de Resonancia Magnética , Metiltransferasas/genética , Modelos Moleculares , Mutación , Unión Proteica , Conformación Proteica , Dominios y Motivos de Interacción de Proteínas , Estabilidad Proteica , Proteínas de Unión al ARN/genética , Relación Estructura-ActividadRESUMEN
Approximately 6-7 million people around the world are estimated to be infected with Trypanosoma cruzi, the causative agent of Chagas disease. The current treatments are inadequate and therefore new medical interventions are urgently needed. In this paper we describe the identification of a series of disubstituted piperazines which shows good potency against the target parasite but is hampered by poor metabolic stability. We outline the strategies used to mitigate this issue such as lowering logD, bioisosteric replacements of the metabolically labile piperazine ring and use of plate-based arrays for quick diversity scoping. We discuss the success of these strategies within the context of this series and highlight the challenges faced in phenotypic programs when attempting to improve the pharmacokinetic profile of compounds whilst maintaining potency against the desired target.
Asunto(s)
Enfermedad de Chagas , Trypanosoma cruzi , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/parasitología , Humanos , Piperazinas/farmacologíaRESUMEN
With increasing drug resistance in tuberculosis (TB) patient populations, there is an urgent need for new drugs. Ideally, new agents should work through novel targets so that they are unencumbered by preexisting clinical resistance to current treatments. Benzofuran 1 was identified as a potential lead for TB inhibiting a novel target, the thioesterase domain of Pks13. Although, having promising activity against Mycobacterium tuberculosis, its main liability was inhibition of the hERG cardiac ion channel. This article describes the optimization of the series toward a preclinical candidate. Despite improvements in the hERG liability in vitro, when new compounds were assessed in ex vivo cardiotoxicity models, they still induced cardiac irregularities. Further series development was stopped because of concerns around an insufficient safety window. However, the demonstration of in vivo activity for multiple series members further validates Pks13 as an attractive novel target for antitubercular drugs and supports development of alternative chemotypes.
Asunto(s)
Antituberculosos/farmacología , Proteínas Bacterianas/antagonistas & inhibidores , Benzofuranos/farmacología , Palmitoil-CoA Hidrolasa/antagonistas & inhibidores , Piperidinas/farmacología , Sintasas Poliquetidas/antagonistas & inhibidores , Benzofuranos/síntesis química , Cardiotoxicidad , Descubrimiento de Drogas , Canal de Potasio ERG1 , Corazón/efectos de los fármacos , Humanos , Pruebas de Sensibilidad Microbiana , Modelos Moleculares , Mycobacterium tuberculosis/efectos de los fármacos , Piperidinas/síntesis química , Relación Estructura-ActividadRESUMEN
With the emergence of multi-drug-resistant strains of Mycobacterium tuberculosis, there is a pressing need for new oral drugs with novel mechanisms of action. A number of scaffolds with potent anti-tubercular in vitro activity have been identified from phenotypic screening that appear to target MmpL3. However, the scaffolds are typically lipophilic, which facilitates partitioning into hydrophobic membranes, and several contain basic amine groups. Highly lipophilic basic amines are typically cytotoxic against mammalian cell lines and have associated off-target risks, such as inhibition of human ether-à-go-go related gene (hERG) and IKr potassium current modulation. The spirocycle compound 3 was reported to target MmpL3 and displayed promising efficacy in a murine model of acute tuberculosis (TB) infection. However, this highly lipophilic monobasic amine was cytotoxic and inhibited the hERG ion channel. Herein, the related spirocycles (1-2) are described, which were identified following phenotypic screening of the Eli Lilly corporate library against M. tuberculosis. The novel N-alkylated pyrazole portion offered improved physicochemical properties, and optimization led to identification of a zwitterion series, exemplified by lead 29, with decreased HepG2 cytotoxicity as well as limited hERG ion channel inhibition. Strains with mutations in MmpL3 were resistant to 29, and under replicating conditions, 29 demonstrated bactericidal activity against M. tuberculosis. Unfortunately, compound 29 had no efficacy in an acute model of TB infection; this was most likely due to the in vivo exposure remaining above the minimal inhibitory concentration for only a limited time.
RESUMEN
Starting from previously disclosed equally potent cathepsin K and S inhibitor 4-propyl-6-(3-trifluoromethylphenyl)pyrimidine-2-carbonitrile 1, a novel 2-phenyl-9H-purine-6-carbonitrile scaffold was identified to provide potent and selective cathepsin S inhibitors.
Asunto(s)
Catepsinas/antagonistas & inhibidores , Nitrilos/química , Inhibidores de Proteasas/química , Purinas/química , Dominio Catalítico , Catepsina K/antagonistas & inhibidores , Catepsina K/metabolismo , Catepsinas/metabolismo , Línea Celular , Simulación por Computador , Humanos , Nitrilos/síntesis química , Nitrilos/farmacología , Inhibidores de Proteasas/síntesis química , Inhibidores de Proteasas/farmacología , Purinas/síntesis química , Purinas/farmacología , Pirimidinas/químicaRESUMEN
6-Phenyl-1H-imidazo[4,5-c]pyridine-4-carbonitrile analogues were identified as potent and selective cathepsin S inhibitor against both purified enzyme and in human JY cell based cellular assays. This core has a very stable thio-trapping nitrile war-head in comparison with the well reported pyrimidine-2-carbonitrile cysteine cathepsin inhibitors. Compound 47 is also very potent in in vivo mouse spleenic Lip10 accumulation assays.
Asunto(s)
Catepsinas/antagonistas & inhibidores , Nitrilos/química , Inhibidores de Proteasas/química , Piridinas/química , Animales , Sitios de Unión , Catepsinas/metabolismo , Línea Celular , Cristalografía por Rayos X , Humanos , Ratones , Nitrilos/síntesis química , Nitrilos/farmacocinética , Inhibidores de Proteasas/síntesis química , Inhibidores de Proteasas/farmacocinética , Piridinas/síntesis química , Piridinas/farmacocinética , Relación Estructura-ActividadRESUMEN
Morphing structural features of HTS-derived chemotypes led to the discovery of novel 2-cyano-pyrimidine inhibitors of cathepsin K with good pharmacokinetic profiles, for example, compound 20 showed high catK potency (IC(50)=4nM), >580-fold selectivity over catL and catB, and oral bioavailability in the rat of 52%.
Asunto(s)
Catepsina K/antagonistas & inhibidores , Inhibidores de Cisteína Proteinasa/química , Pirimidinas/química , Administración Oral , Animales , Sitios de Unión , Catepsina K/metabolismo , Línea Celular , Cristalografía por Rayos X , Inhibidores de Cisteína Proteinasa/síntesis química , Inhibidores de Cisteína Proteinasa/farmacocinética , Diseño de Fármacos , Ensayos Analíticos de Alto Rendimiento , Humanos , Pirimidinas/síntesis química , Pirimidinas/farmacocinética , Ratas , Ratas Sprague-Dawley , Relación Estructura-ActividadRESUMEN
In order to study the role of S1PRs in inflammatory skin disease, S1PR modulators are dosed orally and topically in animal models of disease. The topical application of S1PR modulators in these models may, however, lead to systemic drug concentrations, which can complicate interpretation of the observed effects. We set out to design soft drug S1PR modulators as topical tool compounds to overcome this limitation. A fast follower approach starting from the drug ponesimod allowed the rapid development of an active phenolic series of soft drugs. The phenols were, however, chemically unstable. Protecting the phenol as an ester removed the instability and provided a compound that is converted by enzymatic hydrolysis in the skin to the phenolic soft drug species. In simple formulations, topical dosing of these S1PR modulators to mice led to micromolar skin concentrations but no detectable blood concentrations. These topical tools will allow researchers to investigate the role of S1PR in skin, without involvement of systemic S1PR biology.
RESUMEN
PURPOSE: The detection of a novel psychoactive substance, 2F-MT-45, a fluorinated analogue of the synthetic opioid MT-45, was reported in a single seized tablet. MT-45, 2F-, 3F- and 4F-MT-45 were synthesised and reference analytical data were reported. The in vitro and in vivo metabolisms of MT-45 and 2F-MT-45 were investigated. METHOD: The reference standards and seized sample were characterised using nuclear magnetic resonance spectroscopy, ultra-performance liquid chromatography-quadrupole time of flight mass spectrometry, gas chromatography-mass spectrometry, attenuated total reflectance-Fourier transform infrared spectroscopy and Raman spectroscopy. Presumptive tests were performed and physicochemical properties of the compounds determined. Metabolite identification studies using human liver microsomes, human hepatocytes, mouse hepatocytes and in vivo testing using mice were performed and identified MT-45 metabolites were confirmed in authentic human urine samples. RESULTS: Metabolic pathways identified for MT-45 and 2F-MT-45 were N-dealkylation, hydroxylation and subsequent glucuronidation. The major MT-45 metabolites identified in human in vitro studies and in authenticated human urine were phase I metabolites and should be incorporated as analytical targets to existing toxicological screening methods. Phase II glucuronidated metabolites were present in much lower proportions. CONCLUSIONS: 2F-MT-45 has been detected in a seized tablet for the first time. The metabolite identification data provide useful urinary metabolite targets for forensic and clinical testing for MT-45 and allows screening of urine for 2F-MT-45 and its major metabolites to determine its prevalence in case work.
RESUMEN
With the emergence of multidrug-resistant strains of Mycobacterium tuberculosis there is a pressing need for new oral drugs with novel mechanisms of action. Herein, we describe the identification of a novel morpholino-thiophenes (MOT) series following phenotypic screening of the Eli Lilly corporate library against M. tuberculosis strain H37Rv. The design, synthesis, and structure-activity relationships of a range of analogues around the confirmed actives are described. Optimized leads with potent whole cell activity against H37Rv, no cytotoxicity flags, and in vivo efficacy in an acute murine model of infection are described. Mode-of-action studies suggest that the novel scaffold targets QcrB, a subunit of the menaquinol cytochrome c oxidoreductase, part of the bc1-aa3-type cytochrome c oxidase complex that is responsible for driving oxygen-dependent respiration.
Asunto(s)
Citocromos c/metabolismo , Morfolinas/química , Mycobacterium tuberculosis/efectos de los fármacos , Mycobacterium tuberculosis/enzimología , Oxidorreductasas/metabolismo , Tiofenos/química , Tiofenos/farmacología , Animales , Antituberculosos/química , Antituberculosos/farmacocinética , Antituberculosos/farmacología , Antituberculosos/toxicidad , Chlorocebus aethiops , Ratones , Relación Estructura-Actividad , Tiofenos/farmacocinética , Tiofenos/toxicidad , Células VeroRESUMEN
Mycobacterium tuberculosis ( MTb) possesses two nonproton pumping type II NADH dehydrogenase (NDH-2) enzymes which are predicted to be jointly essential for respiratory metabolism. Furthermore, the structure of a closely related bacterial NDH-2 has been reported recently, allowing for the structure-based design of small-molecule inhibitors. Herein, we disclose MTb whole-cell structure-activity relationships (SARs) for a series of 2-mercapto-quinazolinones which target the ndh encoded NDH-2 with nanomolar potencies. The compounds were inactivated by glutathione-dependent adduct formation as well as quinazolinone oxidation in microsomes. Pharmacokinetic studies demonstrated modest bioavailability and compound exposures. Resistance to the compounds in MTb was conferred by promoter mutations in the alternative nonessential NDH-2 encoded by ndhA in MTb. Bioenergetic analyses revealed a decrease in oxygen consumption rates in response to inhibitor in cells in which membrane potential was uncoupled from ATP production, while inverted membrane vesicles showed mercapto-quinazolinone-dependent inhibition of ATP production when NADH was the electron donor to the respiratory chain. Enzyme kinetic studies further demonstrated noncompetitive inhibition, suggesting binding of this scaffold to an allosteric site. In summary, while the initial MTb SAR showed limited improvement in potency, these results, combined with structural information on the bacterial protein, will aid in the future discovery of new and improved NDH-2 inhibitors.
Asunto(s)
Mycobacterium tuberculosis/enzimología , NADH Deshidrogenasa/química , Quinazolinonas/química , Estructura Molecular , NADH Deshidrogenasa/antagonistas & inhibidores , Quinazolinonas/síntesis química , Quinazolinonas/farmacología , Relación Estructura-ActividadRESUMEN
Chagas' disease, caused by the protozoan parasite Trypanosoma cruzi, is the most common cause of cardiac-related deaths in endemic regions of Latin America. There is an urgent need for new safer treatments because current standard therapeutic options, benznidazole and nifurtimox, have significant side effects and are only effective in the acute phase of the infection with limited efficacy in the chronic phase. Phenotypic high content screening against the intracellular parasite in infected VERO cells was used to identify a novel hit series of 5-amino-1,2,3-triazole-4-carboxamides (ATC). Optimization of the ATC series gave improvements in potency, aqueous solubility, and metabolic stability, which combined to give significant improvements in oral exposure. Mitigation of a potential Ames and hERG liability ultimately led to two promising compounds, one of which demonstrated significant suppression of parasite burden in a mouse model of Chagas' disease.
Asunto(s)
Enfermedad de Chagas/tratamiento farmacológico , Triazoles/química , Triazoles/uso terapéutico , Tripanocidas/química , Tripanocidas/uso terapéutico , Trypanosoma cruzi/efectos de los fármacos , Aminación , Animales , Enfermedad de Chagas/parasitología , Chlorocebus aethiops , Descubrimiento de Drogas , Femenino , Humanos , Ratones , Relación Estructura-Actividad , Triazoles/farmacocinética , Triazoles/farmacología , Tripanocidas/farmacocinética , Tripanocidas/farmacología , Células VeroRESUMEN
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.
Asunto(s)
Aciltransferasas/antagonistas & inhibidores , Pirazoles/síntesis química , Sulfonamidas/síntesis química , Tripanocidas/síntesis química , Tripanosomiasis Africana/tratamiento farmacológico , Aminopiridinas/química , Animales , Barrera Hematoencefálica/efectos de los fármacos , Sistema Nervioso Central/efectos de los fármacos , Femenino , Humanos , Concentración 50 Inhibidora , Ratones , Pirazoles/farmacología , Pirazoles/uso terapéutico , Relación Estructura-Actividad , Sulfonamidas/química , Sulfonamidas/farmacología , Sulfonamidas/uso terapéutico , Tripanocidas/farmacología , Trypanosoma brucei brucei/efectos de los fármacosRESUMEN
Evaluation of safety benefits is an essential taskduring design and development of pedestrian protection systems. Comparative evaluation of different safety concepts is facilitated by a common metric taking into account the expected human benefits. Translation of physical characteristics of a collision, such as impact speed,into human benefits requires reliable and preferably evidence-based injury models. To this end, the dependence of injury severity of body regions on explanatory factors is quantified here using the US Pedestrian Crash Data Study (PCDS) for pedestrians in frontal vehicle collisions. The explanatory and causal factors include vehicle component characteristics, physiological and biomechanical variables, and crash parameters. Severe to serious injuries most often involve the head, thorax and lower extremities. In terms of causing components; severe head and thorax injuries occur mainly on the windshield and hood region; serious lower extremity injuries usually occur on the front bumper. In order to formulate a common metric for evaluating the effect sizes of distinct causal factors, multivariate models of injury severity are obtained by binary logistic regression. Impact speed is clearly the most important injury severity predictor for every body region, although biomechanical and physiological variables as well as geometrical characteristics of the vehicle are also significant in multivariate analysis, even controlling for speed. The injury-metric approach is illustrated in a comparison of hypothetical active and passive safety measures. The relative risk reduction to various body regions by this reduction is formulated as a benchmark for comparison of benefits from proposed structural changes to individual vehicle components.