RESUMO
Radical ipso-substitution offers an alternative to organometallic approaches for biaryl synthesis, but usually requires stoichiometric reagents such as tributyltin hydride. Here, we demonstrate that visible light photoredox catalysis can be used for ipso-biaryl synthesis, via a halogen-atom transfer (XAT) regime. Using amide substrates that promote ipso- over unwanted ortho-addition, we demonstrate smooth biaryl formation with no constraint on the electronic character of the migrating arene ring. The photoreaction can be combined in one operation to achieve a formal arylation of the inert aniline C-N bond.
RESUMO
Anilines are potentially high-value arylating agents, but are limited by the low reactivity of the strong C-N bond. We show that the reactive intermediate benzyne can be used to both activate anilines, and set-up an aryl transfer reaction in a single step. The reaction does not require any transition metal catalysts or stoichiometric organometallics, and establishes a metal-free route to valuable biaryl products by functionalizing the aniline C-N bond.
RESUMO
TREK2 (KCNK10, K2P10.1) is a two-pore domain potassium (K2P) channel and a potential target for the treatment of pain. Like the majority of the K2P superfamily, there is currently a lack of useful pharmacological tools to study TREK2. Here we present a strategy for identifying novel TREK2 activators. A cell-based thallium flux assay was developed and used to screen a library of drug-like molecules, from which we identified the CysLT1 antagonist Pranlukast as a novel activator of TREK2. This compound was selective for TREK2 versus TREK1 and showed no activity at TRAAK. Pranlukast was also screened against other members of the K2P superfamily. Several close analogues of Pranlukast and other CysLT1 antagonists were also tested for their ability to activate K2P channels. Consistent with previous work, structure activity relationships showed that subtle structural changes to these analogues completely attenuated the activation of TREK2, whereas for TREK1, analogues moved from activators to inhibitors. Pranlukast's activity was also confirmed using whole-cell patch clamp electrophysiology. Studies using mutant forms of TREK2 suggest Pranlukast does not bind in the K2P modulator pocket or the BL-1249 binding site. Pranlukast therefore represents a novel tool by which to study the mechanism of TREK2 activation.
Assuntos
Cromonas/farmacologia , Canais de Potássio de Domínios Poros em Tandem/química , Sítios de Ligação , Linhagem Celular Tumoral , Cromonas/química , Cristalografia por Raios X , Humanos , Manejo da Dor , Medição da Dor , Técnicas de Patch-Clamp , Ligação Proteica , Relação Estrutura-Atividade , Tetra-Hidronaftalenos/química , Tetrazóis/química , Tálio/químicaRESUMO
Antibody-drug conjugates (ADCs) are a growing class of therapeutics that harness the specificity of antibodies and the cell-killing potency of small-molecule drugs. Beyond cytotoxics, there are few examples of the application of an ADC approach to difficult drug discovery targets. Here, we present the initial development of a non-internalising ADC, with a view to selectively inhibiting an extracellular protein. Employing the wellinvestigated matrix metalloproteinase-9 (MMP-9) as our model, we adapted a broad-spectrum, nonselective MMP inhibitor for conjugation and linked this to a MMP-9-targeting antibody. The resulting ADC fully inhibits MMP-9, and ELISA results suggest antibody targeting can direct a nonselective inhibitor.
Assuntos
Anticorpos Monoclonais Murinos/imunologia , Ácidos Hidroxâmicos/química , Imunoconjugados/imunologia , Metaloproteinase 9 da Matriz/imunologia , Inibidores de Proteases/química , Pirazinas/química , Animais , Anticorpos Monoclonais Murinos/química , Anticorpos Monoclonais Murinos/metabolismo , Linhagem Celular , Ensaios Enzimáticos , Fluorometria , Humanos , Ácidos Hidroxâmicos/metabolismo , Imunoconjugados/química , Imunoconjugados/metabolismo , Metaloproteinase 9 da Matriz/metabolismo , Camundongos , Inibidores de Proteases/metabolismo , Ligação Proteica , Pirazinas/metabolismo , Sulfonamidas/química , Sulfonamidas/metabolismoRESUMO
Focussed studies on imidazopyridine inhibitors of Plasmodium falciparum cyclic GMP-dependent protein kinase (PfPKG) have significantly advanced the series towards desirable in vitro property space. LLE-based approaches towards combining improvements in cell potency, key physicochemical parameters and structural novelty are described, and a structure-based design hypothesis relating to substituent regiochemistry has directed efforts towards key examples with well-balanced potency, ADME and kinase selectivity profiles.
Assuntos
Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Imidazóis/química , Malária/tratamento farmacológico , Plasmodium falciparum/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Piridinas/química , Compostos Bicíclicos Heterocíclicos com Pontes/química , Humanos , Malária/enzimologia , Malária/parasitologia , Modelos Moleculares , Simulação de Acoplamento Molecular , Plasmodium falciparum/enzimologia , Conformação Proteica , Inibidores de Proteínas Quinases/químicaRESUMO
Development of a class of bicyclic inhibitors of the Plasmodium falciparum cyclic GMP-dependent protein kinase (PfPKG), starting from known compounds with activity against a related parasite PKG orthologue, is reported. Examination of key sub-structural elements led to new compounds with good levels of inhibitory activity against the recombinant kinase and in vitro activity against the parasite. Key examples were shown to possess encouraging in vitro ADME properties, and computational analysis provided valuable insight into the origins of the observed activity profiles.
Assuntos
Antimaláricos/farmacologia , Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Imidazóis/farmacologia , Plasmodium falciparum/efeitos dos fármacos , Inibidores de Proteínas Quinases/farmacologia , Piridinas/farmacologia , Antimaláricos/síntese química , Antimaláricos/química , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Relação Dose-Resposta a Droga , Imidazóis/síntese química , Imidazóis/química , Ligantes , Estrutura Molecular , Testes de Sensibilidade Parasitária , Plasmodium falciparum/enzimologia , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/química , Piridinas/síntese química , Piridinas/química , Relação Estrutura-AtividadeRESUMO
A series of trisubstituted thiazoles have been identified as potent inhibitors of Plasmodium falciparum (Pf) cGMP-dependent protein kinase (PfPKG) through template hopping from known Eimeria PKG (EtPKG) inhibitors. The thiazole series has yielded compounds with improved potency, kinase selectivity and good in vitro ADME properties. These compounds could be useful tools in the development of new anti-malarial drugs in the fight against drug resistant malaria.
Assuntos
Antimaláricos/farmacologia , Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Plasmodium falciparum/enzimologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas de Protozoários/antagonistas & inibidores , Tiazóis/farmacologia , Alquilação , Antimaláricos/química , Humanos , Oxirredução , Inibidores de Proteínas Quinases/química , Relação Estrutura-Atividade , Tiazóis/químicaRESUMO
Two-pore domain potassium channels (K2Ps) are characterized by their four transmembrane domain and two-pore topology. They carry background (or leak) potassium current in a variety of cell types. Despite a number of important roles there is currently a lack of pharmacological tools with which to further probe K2P function. We have developed a cell-based thallium flux assay, using baculovirus delivered TASK3 (TWIK-related acid-sensitive K+ channel 3, KCNK9, K2P9.1) with the aim of identifying novel, selective TASK3 activators. After screening a library of 1000 compounds, including drug-like and FDA approved molecules, we identified Terbinafine as an activator of TASK3. In a thallium flux assay a pEC50 of 6.2 ( ±0.12) was observed. When Terbinafine was screened against TASK2, TREK2, THIK1, TWIK1 and TRESK no activation was observed in thallium flux assays. Several analogues of Terbinafine were also purchased and structure activity relationships examined. To confirm Terbinafine's activation of TASK3 whole cell patch clamp electrophysiology was carried out and clear potentiation observed in both the wild type channel and the pathophysiological, Birk-Barel syndrome associated, G236R TASK3 mutant. No activity at TASK1 was observed in electrophysiology studies. In conclusion, we have identified the first selective activator of the two-pore domain potassium channel TASK3.
Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Ativação do Canal Iônico/fisiologia , Naftalenos/administração & dosagem , Naftalenos/química , Canais de Potássio de Domínios Poros em Tandem/agonistas , Canais de Potássio de Domínios Poros em Tandem/metabolismo , Potássio/metabolismo , Ativação do Canal Iônico/efeitos dos fármacos , Porosidade , Potássio/química , Domínios Proteicos , Relação Estrutura-Atividade , TerbinafinaRESUMO
Targeted protein degradation (TPD) is a rapidly expanding field, with various PROTACs (proteolysis-targeting chimeras) in clinical trials and molecular glues such as immunomodulatory imide drugs (IMiDs) already well established in the treatment of certain blood cancers. Many current approaches are focused on oncology targets, leaving numerous potential applications underexplored. Targeting proteins for degradation offers a novel therapeutic route for targets whose inhibition remains challenging, such as protein aggregates in neurodegenerative diseases. This mini review focuses on the prospect of utilizing TPD for neurodegenerative disease targets, particularly PROTAC and molecular glue formats and opportunities for novel CNS E3 ligases. Some key challenges of utilizing such modalities including molecular design of degrader molecules, drug delivery and blood brain barrier penetrance will be discussed.
RESUMO
The structural diversity and SAR in a series of imidazopyridazine inhibitors of Plasmodium falciparum calcium dependent protein kinase 1 (PfCDPK1) has been explored and extended. The opportunity to further improve key ADME parameters by means of lowering logD was identified, and this was achieved by replacement of a six-membered (hetero)aromatic linker with a pyrazole. A short SAR study has delivered key examples with useful in vitro activity and ADME profiles, good selectivity against a human kinase panel and improved levels of lipophilic ligand efficiency. These new analogues thus provide a credible additional route to further development of the series.
Assuntos
Antimaláricos/química , Antimaláricos/farmacologia , Plasmodium falciparum/enzimologia , Proteínas de Protozoários/antagonistas & inibidores , Piridazinas/química , Piridazinas/farmacologia , Humanos , Malária Falciparum/tratamento farmacológico , Malária Falciparum/parasitologia , Plasmodium falciparum/efeitos dos fármacos , Proteínas Quinases/metabolismo , Proteínas de Protozoários/metabolismoRESUMO
A series of imidazopyridazines which are potent inhibitors of Plasmodium falciparum calcium-dependent protein kinase 1 (PfCDPK1) was identified from a high-throughput screen against the isolated enzyme. Subsequent exploration of the SAR and optimisation has yielded leading members which show promising in vitro anti-parasite activity along with good in vitro ADME and selectivity against human kinases. Initial in vivo testing has revealed good oral bioavailability in a mouse PK study and modest in vivo efficacy in a Plasmodium berghei mouse model of malaria.
Assuntos
Antimaláricos/farmacologia , Malária/tratamento farmacológico , Plasmodium falciparum/enzimologia , Inibidores de Proteínas Quinases/farmacologia , Proteínas de Protozoários/antagonistas & inibidores , Piridazinas/farmacologia , Animais , Antimaláricos/administração & dosagem , Antimaláricos/química , Antimaláricos/uso terapêutico , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Ensaios de Triagem em Larga Escala , Malária/parasitologia , Camundongos , Modelos Moleculares , Estrutura Molecular , Testes de Sensibilidade Parasitária , Plasmodium falciparum/efeitos dos fármacos , Inibidores de Proteínas Quinases/administração & dosagem , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/uso terapêutico , Proteínas Quinases/metabolismo , Proteínas de Protozoários/metabolismo , Piridazinas/administração & dosagem , Piridazinas/química , Relação Estrutura-AtividadeRESUMO
Arylsulfonamides have been found to react with cyclopropane diesters under simple base treatment to give α-arylated pyrrolidinones. This one-pot process comprises three steps: nucleophilic ring-opening of the cyclopropane, reaction of the resulting enolate in a Smiles-Truce aryl transfer, and lactam formation. The reaction represents a new, operationally simple approach to biologically active pyrrolidinones and expands Smiles-Truce arylation methods to encompass sp3 electrophilic centers in cascade processes.
RESUMO
Diarylamines are obtained directly from sulfinamides through a novel rearrangement sequence. The transformation is transition metal-free and proceeds under mild conditions, providing facile access to highly sterically hindered diarylamines that are otherwise inaccessible by traditional SNAr chemistry. The reaction highlights the distinct reactivity of the sulfinamide group in Smiles rearrangements versus that of the more common sulfonamides.
RESUMO
Two classes of trisubstituted pyrimidines related to PI-103 1 have been prepared and their inhibitory activities against phosphatidylinositol 3-kinase (PI3K) p110α were determined. From those with direct 6-aryl substitution compound 11a was the most potent inhibitor with an IC50 value of 62 nM, and showed similar activity against other class 1a PI3K isoforms tested, p110ß and p110γ. When a linking chain was introduced, as in the second exemplified class, compound 15f inhibited p110α with IC50 142 nM, and showed greater selectivity towards p110α. Compounds of both classes showed promising inhibition of cellular proliferation in IGROV-1 ovarian cancer cells. Among compounds designed to replace the 3-phenolic motif with structural isosteres, analogues incorporating a 4-indazolyl group possessed enzyme and cellular activities comparable to the parent phenols.
Assuntos
Morfolinas/química , Fenóis/química , Inibidores de Fosfoinositídeo-3 Quinase , Inibidores de Proteínas Quinases/química , Pirimidinas/química , Animais , Camundongos , Microssomos Hepáticos/metabolismo , Morfolinas/síntese química , Morfolinas/farmacologia , Fenóis/síntese química , Fenóis/farmacologia , Fosfatidilinositol 3-Quinase/metabolismo , Isoformas de Proteínas/antagonistas & inibidores , Isoformas de Proteínas/metabolismo , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/farmacologia , Pirimidinas/síntese química , Pirimidinas/farmacologiaRESUMO
Two-pore domain potassium (K2P) channels carry background (or leak) potassium current and play a key role in regulating resting membrane potential and cellular excitability. Accumulating evidence points to a role for K2Ps in human pathophysiologies, most notably in pain and migraine, making them attractive targets for therapeutic intervention. However, there remains a lack of selective pharmacological tools. The aim of this work was to apply a "target class" approach to investigate the K2P superfamily and identify novel activators across all the described subclasses of K2P channels. Target class drug discovery allows for the leveraging of accumulated knowledge and maximizing synergies across a family of targets and serves as an additional approach to standard target-based screening. A common assay platform using baculovirus (BacMam) to transiently express K2P channels in mammalian cells and a thallium flux assay to determine channel activity was developed, allowing the simultaneous screening of multiple targets. Importantly, this system, by allowing precise titration of channel function, allows optimization to facilitate the identification of activators. A representative set of channels (THIK-1, TWIK-1, TREK-2, TASK-3, and TASK-2) were screened against a library of Food and Drug Administration (FDA)-approved compounds and the LifeArc Index Set. Activators were then analyzed in concentration-response format across all channels to assess selectivity. Using the target class approach to investigate the K2P channels has enabled us to determine which of the K2Ps are amenable to small-molecule activation, de-risk multiple channels from a technical point of view, and identify a diverse range of previously undescribed pharmacology.
Assuntos
Ensaios de Triagem em Larga Escala , Canais de Potássio de Domínios Poros em Tandem/genética , Bibliotecas de Moléculas Pequenas/farmacologia , Baculoviridae/genética , Baculoviridae/metabolismo , Linhagem Celular Tumoral , Clonagem Molecular , Descoberta de Drogas/métodos , Células Epiteliais/citologia , Células Epiteliais/efeitos dos fármacos , Células Epiteliais/metabolismo , Expressão Gênica , Vetores Genéticos/química , Vetores Genéticos/metabolismo , Humanos , Transporte de Íons , Potássio/metabolismo , Canais de Potássio de Domínios Poros em Tandem/agonistas , Canais de Potássio de Domínios Poros em Tandem/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Tálio/metabolismoRESUMO
Co-crystallisation of the imidazo[1,2-a]pyrazine derivative 15 (3-chloro-N-(4-morpholinophenyl)-6-(pyridin-3-yl)imidazo[1,2-a]pyrazin-8-amine) with Aurora-A provided an insight into the interactions of this class of compound with Aurora kinases. This led to the design and synthesis of potent Aurora-A inhibitors demonstrating up to 70-fold selectivity in cell-based Aurora kinase pharmacodynamic biomarker assays.
Assuntos
Antineoplásicos/química , Antineoplásicos/farmacologia , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Pirazinas/química , Pirazinas/farmacologia , Antineoplásicos/síntese química , Aurora Quinases , Linhagem Celular Tumoral , Cristalografia por Raios X , Humanos , Modelos Moleculares , Neoplasias/tratamento farmacológico , Inibidores de Proteínas Quinases/síntese química , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/metabolismo , Pirazinas/síntese química , Relação Estrutura-AtividadeRESUMO
The single-celled apicomplexan parasite Plasmodium falciparum is responsible for the majority of deaths due to malaria each year. The selection of drug resistance has been a recurring theme over the decades with each new drug that is developed. It is therefore crucial that future generations of drugs are explored to tackle this major public health problem. Cyclic GMP (cGMP) signaling is one of the biochemical pathways that is being explored as a potential target for new antimalarial drugs. It has been shown that this pathway is essential for all of the key developmental stages of the complex malaria parasite life cycle. This gives hope that targeting cGMP signaling might give rise to drugs that treat disease, block its transmission and even prevent the establishment of infection. Here we review previous work that has been carried out to develop and optimize inhibitors of the cGMP-dependent protein kinase (PKG) which is a critical regulator of the malaria parasite life cycle.
RESUMO
A high-throughput screening campaign identified a number of imidazopyridazines as novel inhibitors of the malarial kinase PfPK7. Further synthetic chemistry efforts enabled the preparation of a number of analogues with promising in vitro potencies. Although these compounds show likely broad spectrum inhibitory activity, they represent a useful starting point for further chemical optimisation.
Assuntos
Antimaláricos/síntese química , Antimaláricos/farmacologia , Imidazóis/síntese química , Imidazóis/farmacologia , Quinases de Proteína Quinase Ativadas por Mitógeno/antagonistas & inibidores , Plasmodium falciparum/enzimologia , Proteínas de Protozoários/antagonistas & inibidores , Piridazinas/síntese química , Piridazinas/farmacologia , Animais , Antimaláricos/química , Técnicas de Química Combinatória , Desenho de Fármacos , Humanos , Imidazóis/química , Concentração Inibidora 50 , Células KB , Estrutura Molecular , Plasmodium falciparum/efeitos dos fármacos , Piridazinas/química , Relação Estrutura-AtividadeRESUMO
To combat drug resistance, new chemical entities are urgently required for use in next generation anti-malarial combinations. We report here the results of a medicinal chemistry programme focused on an imidazopyridine series targeting the Plasmodium falciparum cyclic GMP-dependent protein kinase (PfPKG). The most potent compound (ML10) has an IC50 of 160 pM in a PfPKG kinase assay and inhibits P. falciparum blood stage proliferation in vitro with an EC50 of 2.1 nM. Oral dosing renders blood stage parasitaemia undetectable in vivo using a P. falciparum SCID mouse model. The series targets both merozoite egress and erythrocyte invasion, but crucially, also blocks transmission of mature P. falciparum gametocytes to Anopheles stephensi mosquitoes. A co-crystal structure of PvPKG bound to ML10, reveals intimate molecular contacts that explain the high levels of potency and selectivity we have measured. The properties of this series warrant consideration for further development to produce an antimalarial drug.Protein kinases are promising drug targets for treatment of malaria. Here, starting with a medicinal chemistry approach, Baker et al. generate an imidazopyridine that selectively targets Plasmodium falciparum PKG, inhibits blood stage parasite growth in vitro and in mice and blocks transmission to mosquitoes.
Assuntos
Proteínas Quinases Dependentes de GMP Cíclico/antagonistas & inibidores , Imidazóis/uso terapêutico , Malária/enzimologia , Malária/transmissão , Piridinas/uso terapêutico , Animais , Linhagem Celular , Cristalografia por Raios X , Culicidae , Proteínas Quinases Dependentes de GMP Cíclico/química , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Modelos Animais de Doenças , Feminino , Humanos , Imidazóis/farmacologia , Estágios do Ciclo de Vida/efeitos dos fármacos , Malária/tratamento farmacológico , Camundongos Endogâmicos BALB C , Modelos Moleculares , Plasmodium chabaudi/efeitos dos fármacos , Plasmodium falciparum/efeitos dos fármacos , Plasmodium falciparum/crescimento & desenvolvimento , Inibidores de Proteínas Quinases/farmacologia , Inibidores de Proteínas Quinases/uso terapêutico , Piridinas/farmacologia , Resultado do TratamentoRESUMO
Rhomboids are evolutionarily conserved serine proteases that cleave transmembrane proteins within the membrane. The increasing number of known rhomboid functions in prokaryotes and eukaryotes makes them attractive drug targets. Here, we describe structures of the Escherichia coli rhomboid GlpG in complex with ß-lactam inhibitors. The inhibitors form a single bond to the catalytic serine and the carbonyl oxygen of the inhibitor faces away from the oxyanion hole. The hydrophobic N-substituent of ß-lactam inhibitors points into a cavity within the enzyme, providing a structural explanation for the specificity of ß-lactams on rhomboid proteases. This same cavity probably represents the S2' substrate binding site of GlpG. We suggest that the structural changes in ß-lactam inhibitor binding reflect the state of the enzyme at an initial stage of substrate binding to the active site. The structural insights from these enzyme-inhibitor complexes provide a starting point for structure-based design for rhomboid inhibitors.