RESUMO
Aminoacyl transfer RNA (tRNA) synthetases (aaRSs) are attractive drug targets, and we present class I and II aaRSs as previously unrecognized targets for adenosine 5'-monophosphate-mimicking nucleoside sulfamates. The target enzyme catalyzes the formation of an inhibitory amino acid-sulfamate conjugate through a reaction-hijacking mechanism. We identified adenosine 5'-sulfamate as a broad-specificity compound that hijacks a range of aaRSs and ML901 as a specific reagent a specific reagent that hijacks a single aaRS in the malaria parasite Plasmodium falciparum, namely tyrosine RS (PfYRS). ML901 exerts whole-life-cycle-killing activity with low nanomolar potency and single-dose efficacy in a mouse model of malaria. X-ray crystallographic studies of plasmodium and human YRSs reveal differential flexibility of a loop over the catalytic site that underpins differential susceptibility to reaction hijacking by ML901.
Assuntos
Antimaláricos , Malária Falciparum , Terapia de Alvo Molecular , Plasmodium falciparum , Biossíntese de Proteínas , Proteínas de Protozoários , Tirosina-tRNA Ligase , Adenosina/análogos & derivados , Animais , Antimaláricos/química , Antimaláricos/farmacologia , Antimaláricos/uso terapêutico , Cristalografia por Raios X , Humanos , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Camundongos , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Biossíntese de Proteínas/efeitos dos fármacos , Conformação Proteica , Proteínas de Protozoários/química , Proteínas de Protozoários/metabolismo , Ácidos Sulfônicos/química , Tirosina-tRNA Ligase/química , Tirosina-tRNA Ligase/metabolismoRESUMO
Cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) signalling is essential for the proliferation of Plasmodium falciparum malaria blood stage parasites. The mechanisms regulating the activity of the catalytic subunit PfPKAc, however, are only partially understood, and PfPKAc function has not been investigated in gametocytes, the sexual blood stage forms that are essential for malaria transmission. By studying a conditional PfPKAc knockdown (cKD) mutant, we confirm the essential role for PfPKAc in erythrocyte invasion by merozoites and show that PfPKAc is involved in regulating gametocyte deformability. We furthermore demonstrate that overexpression of PfPKAc is lethal and kills parasites at the early phase of schizogony. Strikingly, whole genome sequencing (WGS) of parasite mutants selected to tolerate increased PfPKAc expression levels identified missense mutations exclusively in the gene encoding the parasite orthologue of 3-phosphoinositide-dependent protein kinase-1 (PfPDK1). Using targeted mutagenesis, we demonstrate that PfPDK1 is required to activate PfPKAc and that T189 in the PfPKAc activation loop is the crucial target residue in this process. In summary, our results corroborate the importance of tight regulation of PfPKA signalling for parasite survival and imply that PfPDK1 acts as a crucial upstream regulator in this pathway and potential new drug target.
Assuntos
Proteínas Quinases Dependentes de 3-Fosfoinositídeo/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Plasmodium falciparum/metabolismo , Proteínas Quinases Dependentes de 3-Fosfoinositídeo/genética , Animais , Domínio Catalítico , Linhagem Celular , Subunidades Catalíticas da Proteína Quinase Dependente de AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/genética , Eritrócitos/parasitologia , Humanos , Malária , Malária Falciparum/parasitologia , Merozoítos , Parasitos/metabolismo , Proteínas de Protozoários/metabolismoRESUMO
The Plasmodium falciparum proteasome is a potential antimalarial drug target. We have identified a series of amino-amide boronates that are potent and specific inhibitors of the P. falciparum 20S proteasome (Pf20S) ß5 active site and that exhibit fast-acting antimalarial activity. They selectively inhibit the growth of P. falciparum compared with a human cell line and exhibit high potency against field isolates of P. falciparum and Plasmodium vivax They have a low propensity for development of resistance and possess liver stage and transmission-blocking activity. Exemplar compounds, MPI-5 and MPI-13, show potent activity against P. falciparum infections in a SCID mouse model with an oral dosing regimen that is well tolerated. We show that MPI-5 binds more strongly to Pf20S than to human constitutive 20S (Hs20Sc). Comparison of the cryo-electron microscopy (EM) structures of Pf20S and Hs20Sc in complex with MPI-5 and Pf20S in complex with the clinically used anti-cancer agent, bortezomib, reveal differences in binding modes that help to explain the selectivity. Together, this work provides insights into the 20S proteasome in P. falciparum, underpinning the design of potent and selective antimalarial proteasome inhibitors.
Assuntos
Compostos de Boro/farmacologia , Malária Falciparum/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Complexo de Endopeptidases do Proteassoma/química , Inibidores de Proteassoma/farmacologia , Administração Oral , Animais , Compostos de Boro/administração & dosagem , Compostos de Boro/química , Domínio Catalítico , Humanos , Malária Falciparum/enzimologia , Malária Falciparum/parasitologia , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Modelos Moleculares , Plasmodium falciparum/enzimologia , Inibidores de Proteassoma/administração & dosagem , Inibidores de Proteassoma/químicaRESUMO
Malaria control programs continue to be threatened by drug resistance. To identify new antimalarials, we conducted a phenotypic screen and identified a novel tetrazole-based series that shows fast-kill kinetics and a relatively low propensity to develop high-level resistance. Preliminary structure-activity relationships were established including identification of a subseries of related amides with antiplasmodial activity. Assaying parasites with resistance to antimalarials led us to test whether the series had a similar mechanism of action to chloroquine (CQ). Treatment of synchronized Plasmodium falciparum parasites with active analogues revealed a pattern of intracellular inhibition of hemozoin (Hz) formation reminiscent of CQ's action. Drug selections yielded only modest resistance that was associated with amplification of the multidrug resistance gene 1 (pfmdr1). Thus, we have identified a novel chemical series that targets the historically druggable heme polymerization pathway and that can form the basis of future optimization efforts to develop a new malaria treatment.
Assuntos
Amidas/farmacologia , Antimaláricos/farmacologia , Hemoglobinas/metabolismo , Plasmodium falciparum/efeitos dos fármacos , Tetrazóis/farmacologia , Amidas/síntese química , Amidas/farmacocinética , Antimaláricos/síntese química , Antimaláricos/farmacocinética , Resistência Microbiana a Medicamentos/efeitos dos fármacos , Hemeproteínas/antagonistas & inibidores , Células Hep G2 , Humanos , Estrutura Molecular , Testes de Sensibilidade Parasitária , Plasmodium falciparum/metabolismo , Bibliotecas de Moléculas Pequenas/síntese química , Bibliotecas de Moléculas Pequenas/farmacocinética , Bibliotecas de Moléculas Pequenas/farmacologia , Relação Estrutura-Atividade , Tetrazóis/síntese química , Tetrazóis/farmacocinéticaRESUMO
Recent studies on 3,6-diphenylated imidazopyridazines have demonstrated impressive in vitro activity and in vivo efficacy in mouse models of malaria infection. Herein, we report the synthesis and antiplasmodium evaluation of a new series of amidated analogues and demonstrate that these compounds potently inhibit Plasmodium phosphatidylinositol-4-kinase (PI4K) type IIIß while moderately inhibiting cyclic guanidine monophosphate (cGMP)-dependent protein kinase (PKG) activity in vitro. Using in silico docking, we predict key binding interactions for these analogues within the adenosine triphosphate (ATP)-binding site of PI4K and PKG, paving the way for structure-based optimization of imidazopyridazines targeting both Plasmodium PI4K and PKG. While several derivatives showed low nanomolar antiplasmodium activity (IC50 < 100 nM), some compounds, including piperazine analogue 28, resulted in strong dual PI4K and PKG inhibition. The compounds also demonstrated transmission-blocking potential, evident from their potent inhibition of early- and late-stage gametocytes. Finally, the current compounds generally showed improved aqueous solubility and reduced hERG (human ether-a-go-go-related gene) channel inhibition.
Assuntos
1-Fosfatidilinositol 4-Quinase , Plasmodium , Proteínas Quinases Dependentes de GMP Cíclico , Guanidina , Fosfatidilinositóis , Plasmodium falciparum , Proteínas QuinasesRESUMO
Malaria puts at risk nearly half the world's population and causes high mortality in sub-Saharan Africa, while drug resistance threatens current therapies. The pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase (DHODH) is a validated target for malaria treatment based on our finding that triazolopyrimidine DSM265 (1) showed efficacy in clinical studies. Herein, we describe optimization of a pyrrole-based series identified using a target-based DHODH screen. Compounds with nanomolar potency versus Plasmodium DHODH and Plasmodium parasites were identified with good pharmacological properties. X-ray studies showed that the pyrroles bind an alternative enzyme conformation from 1 leading to improved species selectivity versus mammalian enzymes and equivalent activity on Plasmodium falciparum and Plasmodium vivax DHODH. The best lead DSM502 (37) showed in vivo efficacy at similar levels of blood exposure to 1, although metabolic stability was reduced. Overall, the pyrrole-based DHODH inhibitors provide an attractive alternative scaffold for the development of new antimalarial compounds.
Assuntos
Antimaláricos/uso terapêutico , Inibidores Enzimáticos/uso terapêutico , Malária Falciparum/tratamento farmacológico , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Pirróis/uso terapêutico , Animais , Antimaláricos/síntese química , Antimaláricos/metabolismo , Antimaláricos/farmacocinética , Linhagem Celular Tumoral , Cristalografia por Raios X , Di-Hidro-Orotato Desidrogenase , Cães , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/metabolismo , Inibidores Enzimáticos/farmacocinética , Feminino , Humanos , Masculino , Camundongos SCID , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/metabolismo , Testes de Sensibilidade Parasitária , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Plasmodium vivax/efeitos dos fármacos , Plasmodium vivax/enzimologia , Ligação Proteica , Pirróis/síntese química , Pirróis/metabolismo , Pirróis/farmacocinética , Ratos , Relação Estrutura-AtividadeRESUMO
Oligo-arginines are thoroughly studied cell-penetrating peptides (CPPs, Figures 1 and 2). Previous in-vitro investigations with the octaarginine salt of the phosphonate fosmidomycin (herbicide and anti-malaria drug) have shown a 40-fold parasitaemia inhibition with P. falciparum, compared to fosmidomycin alone (Figure 3). We have now tested this salt, as well as the corresponding phosphinate salt of the herbicide glufosinate, for herbicidal activity with whole plants by spray application, hoping for increased activities, i.e. decreased doses. However, both salts showed low herbicidal activity, indicating poor foliar uptake (Table 1). Another pronounced difference between in-vitro and in-vivo activity was demonstrated with various cell-penetrating octaarginine salts of fosmidomycin: intravenous injection to mice caused exitus of the animals within minutes, even at doses as low as 1.4 µmol/kg (Table 2). The results show that use of CPPs for drug delivery, for instance to cancer cells and tissues, must be considered with due care. The biopolymer cyanophycin is a poly-aspartic acid containing argininylated side chains (Figure 4); its building block is the dipeptide H-ßAsp-αArg-OH (H-Adp-OH). To test and compare the biological properties with those of octaarginines we synthesized Adp8-derivatives (Figure 5). Intravenouse injection of H-Adp8-NH2 into the tail vein of mice with doses as high as 45 µmol/kg causes no symptoms whatsoever (Table 3), but H-Adp8-NH2 is not cell penetrating (HEK293 and MCF-7 cells, Figure 6). On the other hand, the fluorescently labeled octamers FAM-(Adp(OMe))8-NH2 and FAM-(Adp(NMe2))8-NH2 with ester and amide groups in the side chains exhibit mediocre to high cell-wall permeability (Figure 6), and are toxic (Table 3). Possible reasons for this behavior are discussed (Figure 7) and corresponding NMR spectra are presented (Figure 8).
RESUMO
Structural optimization of 3-hydroxy-N'-arylidenepropanehydrazonamides provided new analogs with nanomolar to subnanomolar antiplasmodial activity against asexual blood stages of Plasmodium falciparum, excellent parasite selectivity, and nanomolar activity against the earliest forms of gametocyte development. Particularly, derivatives with a 1,3-dihalo-6-trifluoromethylphenanthrene moiety showed outstanding in vivo properties and demonstrated in part curative activity in the Plasmodium berghei mouse model when administered perorally.
Assuntos
Amidas/química , Antimaláricos/química , Hidrazonas/química , Malária/tratamento farmacológico , Fenantrenos/química , Plasmodium berghei/efeitos dos fármacos , Amidas/síntese química , Amidas/farmacologia , Animais , Antimaláricos/síntese química , Antimaláricos/farmacologia , Células Hep G2 , Humanos , Hidrazonas/síntese química , Hidrazonas/farmacologia , Malária/parasitologia , Camundongos , Fenantrenos/síntese química , Fenantrenos/farmacologia , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
Introduction of water-solubilizing groups on the 5-phenyl ring of a 2-aminopyrazine series led to the identification of highly potent compounds against the blood life-cycle stage of the human malaria parasite Plasmodium falciparum. Several compounds displayed high in vivo efficacy in two different mouse models for malaria, P. berghei-infected mice and P. falciparum-infected NOD-scid IL-2Rγnull mice. One of the frontrunners, compound 3, was identified to also have good pharmacokinetics and additionally very potent activity against the liver and gametocyte parasite life-cycle stages.
Assuntos
Antimaláricos/farmacologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Malária/tratamento farmacológico , Doenças Parasitárias em Animais/tratamento farmacológico , Plasmodium berghei/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Pirazinas/farmacologia , Animais , Antimaláricos/química , Antimaláricos/metabolismo , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Canais de Potássio Éter-A-Go-Go/metabolismo , Células Hep G2 , Humanos , Camundongos , Camundongos SCID , Microssomos Hepáticos/química , Microssomos Hepáticos/metabolismo , Estrutura Molecular , Doenças Parasitárias em Animais/parasitologia , Testes de Sensibilidade Parasitária , Plasmodium berghei/crescimento & desenvolvimento , Plasmodium falciparum/crescimento & desenvolvimento , Pirazinas/química , Pirazinas/metabolismo , Solubilidade , Relação Estrutura-Atividade , Água/químicaRESUMO
Plasmodium falciparum dihydroorotate dehydrogenase (PfDHODH), a key enzyme in the de novo pyrimidine biosynthesis pathway, which the Plasmodium falciparum relies on exclusively for survival, has emerged as a promising target for antimalarial drugs. In an effort to discover new and potent PfDHODH inhibitors, 3D-QSAR pharmacophore models were developed based on the structures of known PfDHODH inhibitors and the validated Hypo1 model was used as a 3D search query for virtual screening of the National Cancer Institute database. The virtual hit compounds were further filtered based on molecular docking and Molecular Mechanics/Generalized Born Surface Area binding energy calculations. The combination of the pharmacophore and structure-based virtual screening resulted in the identification of nine new compounds that showed >25% inhibition of PfDHODH at a concentration of 10 µM, three of which exhibited IC50 values in the range of 0.38-20 µM. The most active compound, NSC336047, displayed species-selectivity for PfDHODH over human DHODH and inhibited parasite growth with an IC50 of 26 µM. In addition to this, 13 compounds inhibited parasite growth with IC50 values of ≤ 50 µM, 4 of which showed IC50 values in the range of 5-12 µM. These compounds could be further explored in the identification and development of more potent PfDHODH and parasite growth inhibitors.
Assuntos
Inibidores Enzimáticos/farmacologia , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Plasmodium falciparum/efeitos dos fármacos , Animais , Di-Hidro-Orotato Desidrogenase , Humanos , Plasmodium falciparum/enzimologia , Relação Quantitativa Estrutura-AtividadeRESUMO
The heme-containing enzymes indoleamine 2,3-dioxygenase-1 (IDO-1) and IDO-2 catalyze the conversion of the essential amino acid tryptophan into kynurenine. Metabolites of the kynurenine pathway and IDO itself are involved in immunity and the pathology of several diseases, having either immunoregulatory or antimicrobial effects. IDO-1 plays a central role in the pathogenesis of cerebral malaria, which is the most severe and often fatal neurological complication of infection with Plasmodium falciparum. Mouse models are usually used to study the underlying pathophysiology. In this study, we screened a natural compound library against mouse IDO-1 and identified 8-aminobenzo[b]quinolizinium (compound 2c) to be an inhibitor of IDO-1 with potency at nanomolar concentrations (50% inhibitory concentration, 164 nM). Twenty-one structurally modified derivatives of compound 2c were synthesized for structure-activity relationship analyses. The compounds were found to be selective for IDO-1 over IDO-2. We therefore compared the roles of prominent amino acids in the catalytic mechanisms of the two isoenzymes via homology modeling, site-directed mutagenesis, and kinetic analyses. Notably, methionine 385 of IDO-2 was identified to interfere with the entrance of l-tryptophan to the active site of the enzyme, which explains the selectivity of the inhibitors. Most interestingly, several benzo[b]quinolizinium derivatives (6 compounds with 50% effective concentration values between 2.1 and 6.7 nM) were found to be highly effective against P. falciparum 3D7 blood stages in cell culture with a mechanism independent of IDO-1 inhibition. We believe that the class of compounds presented here has unique characteristics; it combines the inhibition of mammalian IDO-1 with strong antiparasitic activity, two features that offer potential for drug development.
Assuntos
Antimaláricos/farmacologia , Indolamina-Pirrol 2,3,-Dioxigenase/antagonistas & inibidores , Malária/tratamento farmacológico , Plasmodium berghei/efeitos dos fármacos , Quinolizinas/farmacologia , Animais , Antimaláricos/síntese química , Antimaláricos/química , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Clonagem Molecular , Cristalografia por Raios X , Eritrócitos/efeitos dos fármacos , Eritrócitos/parasitologia , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Humanos , Indolamina-Pirrol 2,3,-Dioxigenase/química , Indolamina-Pirrol 2,3,-Dioxigenase/genética , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Cinurenina/metabolismo , Malária/parasitologia , Camundongos , Mutagênese Sítio-Dirigida , Plasmodium berghei/enzimologia , Plasmodium berghei/genética , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/enzimologia , Plasmodium falciparum/genética , Quinolizinas/síntese química , Quinolizinas/química , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Relação Estrutura-Atividade , Triptofano/antagonistas & inibidores , Triptofano/metabolismoRESUMO
Toward improving pharmacokinetics, in vivo efficacy, and selectivity over hERG, structure-activity relationship studies around the central core of antimalarial imidazopyridazines were conducted. This study led to the identification of potent pyrazolopyridines, which showed good in vivo efficacy and pharmacokinetics profiles. The lead compounds also proved to be very potent in the parasite liver and gametocyte stages, which makes them of high interest.
Assuntos
Antimaláricos/química , Antimaláricos/uso terapêutico , Malária/tratamento farmacológico , Plasmodium berghei/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Pirazóis/química , Pirazóis/uso terapêutico , Piridinas/química , Piridinas/uso terapêutico , Animais , Antimaláricos/farmacocinética , Antimaláricos/farmacologia , Canais de Potássio Éter-A-Go-Go/metabolismo , Humanos , Fígado/parasitologia , Malária/parasitologia , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Camundongos , Pirazóis/farmacocinética , Pirazóis/farmacologia , Piridinas/farmacocinética , Piridinas/farmacologia , Ratos , Relação Estrutura-AtividadeRESUMO
Based on the initial optimization of orally active antimalarial 2,4-diamino-thienopyrimidines and with the help of metabolite identification studies, a second generation of derivatives involving changes at the 2- and 4-positions of the thienopyrimidine core were synthesized. Improvements in the physiochemical properties resulted in the identification of 15a, 17a, 32, and 40 as lead molecules with improved in vivo exposure. Furthermore, analogue 40 exhibited excellent in vivo antimalarial activity when dosed orally at 50 mg/kg once daily for 4 days in the Plasmodium berghei mouse model, which is superior to the activity seen with previously reported compounds, and with a slightly improved hERG profile.
Assuntos
Antimaláricos/química , Pirimidinas/química , Administração Oral , Animais , Antimaláricos/farmacocinética , Antimaláricos/farmacologia , Cristalografia por Raios X , Resistência a Medicamentos , Canais de Potássio Éter-A-Go-Go/fisiologia , Feminino , Humanos , Malária/tratamento farmacológico , Malária/parasitologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Microssomos Hepáticos/metabolismo , Técnicas de Patch-Clamp , Plasmodium berghei , Plasmodium falciparum/efeitos dos fármacos , Conformação Proteica , Pirimidinas/farmacocinética , Pirimidinas/farmacologia , Solubilidade , Relação Estrutura-AtividadeRESUMO
Malaria is one of the most significant causes of childhood mortality, but disease control efforts are threatened by resistance of the Plasmodium parasite to current therapies. Continued progress in combating malaria requires development of new, easy to administer drug combinations with broad-ranging activity against all manifestations of the disease. DSM265, a triazolopyrimidine-based inhibitor of the pyrimidine biosynthetic enzyme dihydroorotate dehydrogenase (DHODH), is the first DHODH inhibitor to reach clinical development for treatment of malaria. We describe studies profiling the biological activity, pharmacological and pharmacokinetic properties, and safety of DSM265, which supported its advancement to human trials. DSM265 is highly selective toward DHODH of the malaria parasite Plasmodium, efficacious against both blood and liver stages of P. falciparum, and active against drug-resistant parasite isolates. Favorable pharmacokinetic properties of DSM265 are predicted to provide therapeutic concentrations for more than 8 days after a single oral dose in the range of 200 to 400 mg. DSM265 was well tolerated in repeat-dose and cardiovascular safety studies in mice and dogs, was not mutagenic, and was inactive against panels of human enzymes/receptors. The excellent safety profile, blood- and liver-stage activity, and predicted long half-life in humans position DSM265 as a new potential drug combination partner for either single-dose treatment or once-weekly chemoprevention. DSM265 has advantages over current treatment options that are dosed daily or are inactive against the parasite liver stage.
Assuntos
Antimaláricos/química , Inibidores Enzimáticos/química , Malária Falciparum/tratamento farmacológico , Malária Falciparum/prevenção & controle , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/antagonistas & inibidores , Pirimidinas/química , Triazóis/química , Administração Oral , Animais , Antimaláricos/farmacocinética , Área Sob a Curva , Células CACO-2 , Cristalografia por Raios X , Di-Hidro-Orotato Desidrogenase , Cães , Avaliação Pré-Clínica de Medicamentos , Inibidores Enzimáticos/farmacocinética , Haplorrinos , Humanos , Concentração Inibidora 50 , Camundongos , Camundongos Endogâmicos NOD , Camundongos SCID , Dados de Sequência Molecular , Oxirredutases atuantes sobre Doadores de Grupo CH-CH/química , Plasmodium falciparum , Pirimidinas/farmacocinética , Coelhos , Especificidade por Substrato , Triazóis/farmacocinéticaRESUMO
One new isochromane (pseudoanguillosporin C, 2), seven isochromanones (soudanones A-G, 3-9), and six known analogues including 10 and 11 were isolated from a culture of the fungus Cadophora sp. 10-5-2 M, collected from the subterranean 10th level of the Soudan Underground Iron Mine in Minnesota. All of the compounds were tested against a panel of microbial pathogens, and 2, 3, 10, and 11 were found to have activity against Cryptococcus neoformans (MIC = 35, 40, 20, and 30 µg/mL, respectively). Compound 11 was also active against Candida albicans, with an MIC of 40 µg/mL.
Assuntos
Antifúngicos/isolamento & purificação , Antifúngicos/farmacologia , Cromonas/isolamento & purificação , Antifúngicos/química , Candida albicans/efeitos dos fármacos , Cromanos , Cromonas/química , Cromonas/farmacologia , Cryptococcus neoformans/efeitos dos fármacos , Ferro , Testes de Sensibilidade Microbiana , Mineração , Minnesota , Estrutura Molecular , Ressonância Magnética Nuclear BiomolecularRESUMO
Several of the enzymes related to the folate cycle are well-known for their role as clinically validated antimalarial targets. Nevertheless for serine hydroxymethyltransferase (SHMT), one of the key enzymes of this cycle, efficient inhibitors have not been described so far. On the basis of plant SHMT inhibitors from an herbicide optimization program, highly potent inhibitors of Plasmodium falciparum (Pf) and Plasmodium vivax (Pv) SHMT with a pyrazolopyran core structure were identified. Cocrystal structures of potent inhibitors with PvSHMT were solved at 2.6 Å resolution. These ligands showed activity (IC50/EC50 values) in the nanomolar range against purified PfSHMT, blood-stage Pf, and liver-stage P. berghei (Pb) cells and a high selectivity when assayed against mammalian cell lines. Pharmacokinetic limitations are the most plausible explanation for lack of significant activity of the inhibitors in the in vivo Pb mouse malaria model.
Assuntos
Antimaláricos/química , Antimaláricos/farmacologia , Inibidores Enzimáticos/química , Inibidores Enzimáticos/farmacologia , Glicina Hidroximetiltransferase/antagonistas & inibidores , Plasmodium falciparum/efeitos dos fármacos , Plasmodium vivax/efeitos dos fármacos , Administração Oral , Animais , Antimaláricos/administração & dosagem , Antimaláricos/farmacocinética , Técnicas de Química Sintética , Cristalografia por Raios X , Avaliação Pré-Clínica de Medicamentos/métodos , Resistência a Medicamentos/efeitos dos fármacos , Inibidores Enzimáticos/síntese química , Feminino , Glicina Hidroximetiltransferase/química , Glicina Hidroximetiltransferase/metabolismo , Células Hep G2/efeitos dos fármacos , Humanos , Fígado/metabolismo , Fígado/parasitologia , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Camundongos Endogâmicos , Camundongos SCID , Microssomos Hepáticos/efeitos dos fármacos , Organismos Geneticamente Modificados , Plasmodium berghei/efeitos dos fármacos , Plasmodium berghei/patogenicidade , Plasmodium falciparum/enzimologia , Plasmodium falciparum/patogenicidade , Plasmodium vivax/enzimologia , Plasmodium vivax/patogenicidade , Pirazóis/química , RatosRESUMO
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.
Assuntos
Antimaláricos/uso terapêutico , Azepinas/uso terapêutico , Histona-Lisina N-Metiltransferase/antagonistas & inibidores , Malária/tratamento farmacológico , Quinazolinas/uso terapêutico , Animais , Antimaláricos/química , Azepinas/química , Feminino , Células Hep G2 , Histona Metiltransferases , Humanos , Malária Falciparum/tratamento farmacológico , Camundongos , Camundongos SCID , Plasmodium berghei/efeitos dos fármacos , Plasmodium berghei/patogenicidade , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/patogenicidade , Quinazolinas/químicaRESUMO
On the basis of our recent results on a novel series of imidazopyridazine-based antimalarials, we focused on identifying compounds with improved aqueous solubility and hERG profile while maintaining metabolic stability and in vitro potency. Toward this objective, 41 compounds were synthesized and evaluated for antiplasmodial activity against NF54 (sensitive) and K1 (multidrug resistant) strains of the malaria parasite Plasmodium falciparum and evaluated for both aqueous solubility and metabolic stability. Selected compounds were tested for in vitro hERG activity and in vivo efficacy in the P. berghei mouse model. Several compounds were identified with significantly improved aqueous solubility, good metabolic stability, and a clean hERG profile relative to a previous frontrunner lead compound. A sulfoxide-based imidazopyridazine analog 45, arising from a prodrug-like strategy, was completely curative in the Plasmodium berghei mouse model at 4 × 50 mg/kg po.
Assuntos
Antimaláricos/síntese química , Piridazinas/síntese química , Sulfonas/síntese química , Animais , Antimaláricos/metabolismo , Antimaláricos/farmacocinética , Antimaláricos/farmacologia , Resistência a Múltiplos Medicamentos , Canais de Potássio Éter-A-Go-Go/efeitos dos fármacos , Humanos , Malária Falciparum/parasitologia , Masculino , Camundongos , Microssomos Hepáticos/metabolismo , Testes de Sensibilidade Parasitária , Plasmodium berghei/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Piridazinas/metabolismo , Piridazinas/farmacologia , Ratos Sprague-Dawley , Solubilidade , Relação Estrutura-Atividade , Sulfonas/metabolismo , Sulfonas/farmacologiaRESUMO
A novel series of 2,4-diaminothienopyrimidines with potential as antimalarials was identified from whole-cell high-throughput screening of a SoftFocus ion channel library. Synthesis and structure-activity relationship studies identified compounds with potent antiplasmodial activity and low in vitro cytotoxicity. Several of these analogues exhibited in vivo activity in the Plasmodium berghei mouse model when administered orally. However, inhibition of the hERG potassium channel was identified as a liability for this series.
Assuntos
Antimaláricos/síntese química , Pirimidinas/síntese química , Tiofenos/síntese química , Administração Oral , Animais , Antimaláricos/química , Antimaláricos/farmacologia , Linhagem Celular , Bases de Dados de Compostos Químicos , Resistência a Múltiplos Medicamentos , Canal de Potássio ERG1 , Canais de Potássio Éter-A-Go-Go/antagonistas & inibidores , Ensaios de Triagem em Larga Escala , Humanos , Malária/tratamento farmacológico , Malária/parasitologia , Masculino , Camundongos , Microssomos Hepáticos/metabolismo , Plasmodium berghei , Plasmodium falciparum/efeitos dos fármacos , Pirimidinas/química , Pirimidinas/farmacologia , Ratos , Ratos Sprague-Dawley , Relação Estrutura-Atividade , Tiofenos/química , Tiofenos/farmacologiaRESUMO
In an effort to address potential cardiotoxicity liabilities identified with earlier frontrunner compounds, a number of new 3,5-diaryl-2-aminopyridine derivatives were synthesized. Several compounds exhibited potent antiplasmodial activity against both the multidrug resistant (K1) and sensitive (NF54) strains in the low nanomolar range. Some compounds displayed a significant reduction in potency in the hERG channel inhibition assay compared to previously reported frontrunner analogues. Several of these new analogues demonstrated promising in vivo efficacy in the Plasmodium berghei mouse model and will be further evaluated as potential clinical candidates. The SAR for in vitro antiplasmodial and hERG activity was delineated.