RESUMEN

Fifteen compounds were isolated from the 70% EtOH extract of leaves of Chinese hawthorn(Crataegus pinnatifida var. major) by various purification steps, and their structures were determined as 2α,3α,12ß,19α,-tetrahydroxyursan-13ß,28-olide(1),euscaphic acid(2), tormentic acid(3), ursolic acid(4), pomolic acid(5), corosolic acid(6), maslinic acid(7), linalyl rutinoside(8),(Z)-3-hexenyl ß-D-glucoside(9),(3S, 6S)-cis-linalool-3,7-oxide-ß-D-glucopyranoside(10), pisumionoside(11), icariside B6(12), byzantionoside B(13),(6R,7E,9R)-9-Hydroxy-4,7-megastigmadien-3-one 9-O-ß-D-glucopyranoside(14) and(6S,7E,9R)-6,9-dihydroxy-4,7-megastigmadien-3-one 9-O-ß-D-glucopyranoside(15) mainly based on the mass spectrum(MS) and nuclear magnetic resonance(NMR) spectroscopic techniques, of which compound 1 was a new pentacyclic triterpene, and compounds 2, 5, 6, 8, 10, 13 and 15 were isolated form this plant for the first time.

Asunto(s)

Crataegus , China , Estructura Molecular , Hojas de la Planta , Terpenos , Triterpenos

RESUMEN

A phytochemical study on the leaves of Crataegus pinnatifida Bge. var. major N.E.Br. was carried out, which finally led to the isolation of nineteen phenolic compounds (1-19). The structures of all compounds were established mainly by NMR and MS spectroscopic analysis as well as the necessary ECD experimental evidence, of which compounds 1-4 (crataegunins A-D) were identified as new phenylpropanoid-substituted epicatechins. HepG2 cells were induced by oleic acid and palmitic acid to establish the model of lipid metabolism disorder. All isolated compounds were used to intervene in the model, and the contents of triglyceride (TG) and total cholesterol (TC) were detected. Compound 2 could significantly reduce the content of TG, while compounds 2 and 11 both have good activity in reducing TC content.

Asunto(s)

Crataegus/química , Fenoles/farmacología , Hojas de la Planta/química , Triglicéridos/antagonistas & inhibidores , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Células Hep G2 , Humanos , Estructura Molecular , Fenoles/química , Fenoles/aislamiento & purificación , Relación Estructura-Actividad , Triglicéridos/análisis

RESUMEN

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

RESUMEN

There is an urgent need for new antibiotics against Gram-negative pathogens that are resistant to carbapenem and third-generation cephalosporins, against which antibiotics of last resort have lost most of their efficacy. Here we describe a class of synthetic antibiotics inspired by scaffolds derived from natural products. These chimeric antibiotics contain a ß-hairpin peptide macrocycle linked to the macrocycle found in the polymyxin and colistin family of natural products. They are bactericidal and have a mechanism of action that involves binding to both lipopolysaccharide and the main component (BamA) of the ß-barrel folding complex (BAM) that is required for the folding and insertion of ß-barrel proteins into the outer membrane of Gram-negative bacteria. Extensively optimized derivatives show potent activity against multidrug-resistant pathogens, including all of the Gram-negative members of the ESKAPE pathogens1. These derivatives also show favourable drug properties and overcome colistin resistance, both in vitro and in vivo. The lead candidate is currently in preclinical toxicology studies that-if successful-will allow progress into clinical studies that have the potential to address life-threatening infections by the Gram-negative pathogens, and thus to resolve a considerable unmet medical need.

Asunto(s)

Antibacterianos/química , Antibacterianos/farmacología , Farmacorresistencia Microbiana , Bacterias Gramnegativas/efectos de los fármacos , Peptidomiméticos/química , Peptidomiméticos/farmacología , Animales , Antibacterianos/efectos adversos , Proteínas de la Membrana Bacteriana Externa/química , Proteínas de la Membrana Bacteriana Externa/genética , Productos Biológicos/química , Descubrimiento de Drogas , Farmacorresistencia Microbiana/efectos de los fármacos , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Fluorescencia , Bacterias Gramnegativas/genética , Bacterias Gramnegativas/patogenicidad , Humanos , Lipopolisacáridos/química , Compuestos Macrocíclicos/efectos adversos , Compuestos Macrocíclicos/química , Compuestos Macrocíclicos/farmacología , Masculino , Ratones , Pruebas de Sensibilidad Microbiana , Viabilidad Microbiana/efectos de los fármacos , Microscopía Electrónica de Transmisión , Modelos Moleculares , Mutación , Peptidomiméticos/efectos adversos , Etiquetas de Fotoafinidad

RESUMEN

The histone acetyl reader bromodomain-containing protein 4 (BRD4) is an important regulator of chromatin structure and transcription, yet factors modulating its activity have remained elusive. Here we describe two complementary screens for genetic and physical interactors of BRD4, which converge on the folate pathway enzyme MTHFD1 (methylenetetrahydrofolate dehydrogenase, cyclohydrolase and formyltetrahydrofolate synthetase 1). We show that a fraction of MTHFD1 resides in the nucleus, where it is recruited to distinct genomic loci by direct interaction with BRD4. Inhibition of either BRD4 or MTHFD1 results in similar changes in nuclear metabolite composition and gene expression; pharmacological inhibitors of the two pathways synergize to impair cancer cell viability in vitro and in vivo. Our finding that MTHFD1 and other metabolic enzymes are chromatin associated suggests a direct role for nuclear metabolism in the control of gene expression.

Asunto(s)

Ácido Fólico/metabolismo , Regulación de la Expresión Génica , Metilenotetrahidrofolato Deshidrogenasa (NADP)/metabolismo , Antígenos de Histocompatibilidad Menor/metabolismo , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Proteínas de Ciclo Celular , Línea Celular Tumoral , Núcleo Celular/metabolismo , Cromatina/genética , Técnicas de Inactivación de Genes , Humanos , Mutación con Pérdida de Función , Unión Proteica , Mapeo de Interacción de Proteínas , Mapas de Interacción de Proteínas , Transporte de Proteínas , Transducción de Señal , Transcripción Genética

RESUMEN

The MYC oncoprotein binds to promoter-proximal regions of virtually all transcribed genes and enhances RNA polymerase II (Pol II) function, but its precise mode of action is poorly understood. Using mass spectrometry of both MYC and Pol II complexes, we show here that MYC controls the assembly of Pol II with a small set of transcription elongation factors that includes SPT5, a subunit of the elongation factor DSIF. MYC directly binds SPT5, recruits SPT5 to promoters, and enables the CDK7-dependent transfer of SPT5 onto Pol II. Consistent with known functions of SPT5, MYC is required for fast and processive transcription elongation. Intriguingly, the high levels of MYC that are expressed in tumors sequester SPT5 into non-functional complexes, thereby decreasing the expression of growth-suppressive genes. Altogether, these results argue that MYC controls the productive assembly of processive Pol II elongation complexes and provide insight into how oncogenic levels of MYC permit uncontrolled cellular growth.

Asunto(s)

Proteínas Nucleares/genética , Proteínas Proto-Oncogénicas c-myc/genética , ARN Polimerasa II/genética , Transcripción Genética , Factores de Elongación Transcripcional/genética , Línea Celular Tumoral , Proliferación Celular/genética , Quinasas Ciclina-Dependientes/genética , Chaperonas de Histonas/genética , Humanos , Neoplasias/genética , Regiones Promotoras Genéticas , Quinasa Activadora de Quinasas Ciclina-Dependientes

RESUMEN

With the increasing resistance of many Gram-negative bacteria to existing classes of antibiotics, identifying new paradigms in antimicrobial discovery is an important research priority. Of special interest are the proteins required for the biogenesis of the asymmetric Gram-negative bacterial outer membrane (OM). Seven Lpt proteins (LptA to LptG) associate in most Gram-negative bacteria to form a macromolecular complex spanning the entire envelope, which transports lipopolysaccharide (LPS) molecules from their site of assembly at the inner membrane to the cell surface, powered by adenosine 5'-triphosphate hydrolysis in the cytoplasm. The periplasmic protein LptA comprises the protein bridge across the periplasm, which connects LptB2FGC at the inner membrane to LptD/E anchored in the OM. We show here that the naturally occurring, insect-derived antimicrobial peptide thanatin targets LptA and LptD in the network of periplasmic protein-protein interactions required to assemble the Lpt complex, leading to the inhibition of LPS transport and OM biogenesis in Escherichia coli.

Asunto(s)

Péptidos Catiónicos Antimicrobianos/farmacología , Proteínas de la Membrana Bacteriana Externa/metabolismo , Proteínas de Escherichia coli/metabolismo , Escherichia coli/metabolismo , Lipopolisacáridos/metabolismo , Proteínas de la Membrana Bacteriana Externa/química , Proteínas de la Membrana Bacteriana Externa/genética , Transporte Biológico Activo , Escherichia coli/efectos de los fármacos , Escherichia coli/crecimiento & desarrollo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/genética , Modelos Moleculares , Conformación Proteica

RESUMEN

The globus pallidus is a central nucleus in the basal ganglia motor control circuit. Morphological studies have revealed the expression of adenosine A2A receptors in the globus pallidus. To determine the modulation of adenosine A2A receptors on the activity of pallidal neurons in both normal and parkinsonian rats, in vivo electrophysiological and behavioral tests were performed in the present study. The extracellular single unit recordings showed that micro-pressure administration of adenosine A2A receptor agonist, CGS21680, regulated the pallidal firing activity. GABAergic neurotransmission was involved in CGS21680-induced modulation of pallidal neurons via a PKA pathway. Furthermore, application of two adenosine A2A receptor antagonists, KW6002 or SCH442416, mainly increased the spontaneous firing of pallidal neurons, suggesting that endogenous adenosine system modulates the activity of pallidal neurons through adenosine A2A receptors. Finally, elevated body swing test (EBST) showed that intrapallidal microinjection of adenosine A2A receptor agonist/antagonist induced ipsilateral/contralateral-biased swing, respectively. In addition, the electrophysiological and behavioral findings also revealed that activation of dopamine D2 receptors by quinpirole strengthened KW6002/SCH442416-induced excitation of pallidal activity. Co-application of quinpirole with KW6002 or SCH442416 alleviated biased swing in hemi-parkinsonian rats. Based on the present findings, we concluded that pallidal adenosine A2A receptors may be potentially useful in the treatment of Parkinson's disease.

RESUMEN

A series of analogues based on serine as lead structure were designed, and their agonist activities were evaluated at recombinant NMDA receptor subtypes (GluN1/2A-D) using two-electrode voltage-clamp (TEVC) electrophysiology. Pronounced variation in subunit-selectivity, potency, and agonist efficacy was observed in a manner that was dependent on the GluN2 subunit in the NMDA receptor. In particular, compounds 15a and 16a are potent GluN2C-specific superagonists at the GluN1 subunit with agonist efficacies of 398% and 308% compared to glycine. This study demonstrates that subunit-selectivity among glycine site NMDA receptor agonists can be achieved and suggests that glycine-site agonists can be developed as pharmacological tool compounds to study GluN2C-specific effects in NMDA receptor-mediated neurotransmission.

Asunto(s)

Agonistas de Aminoácidos Excitadores/farmacología , Receptores de N-Metil-D-Aspartato/agonistas , Animales , Sitios de Unión , Relación Dosis-Respuesta a Droga , Agonistas de Aminoácidos Excitadores/química , Glicina/metabolismo , Glicina/farmacología , Potenciales de la Membrana/efectos de los fármacos , Potenciales de la Membrana/fisiología , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Oocitos , Técnicas de Placa-Clamp , Unión Proteica , Multimerización de Proteína , Receptores de N-Metil-D-Aspartato/metabolismo , Proteínas Recombinantes/metabolismo , Estereoisomerismo , Xenopus laevis

RESUMEN

A series of analogues of the (S)-2-Amino-3-(3-hydroxy-5-methyl-isoxazol-4-yl)propionic acid (AMPA) receptor agonist BnTetAMPA (5b) were synthesized and characterized pharmacologically in radioligand binding assays at native and cloned AMPA receptors and functionally by two-electrode voltage clamp electrophysiology at the four homomeric AMPA receptors expressed in Xenopus laevis oocytes. The analogues 6 and 7 exhibit very different pharmacological profiles with binding affinity preference for the subtypes GluA1 and GluA3, respectively. X-ray crystal structures of three ligands (6, 7, and 8) in complex with the agonist binding domain (ABD) of GluA2 show that they induce full domain closure despite their low agonist efficacies. Trp767 in GluA2 ABD could be an important determinant for partial agonism of this compound series at AMPA receptors, since agonist efficacy also correlated with the location of the Trp767 side chain.

Asunto(s)

Alanina/análogos & derivados , Isoxazoles/farmacología , Receptores AMPA/agonistas , Alanina/síntesis química , Alanina/química , Alanina/farmacología , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Cristalografía por Rayos X , Relación Dosis-Respuesta a Droga , Células HEK293 , Humanos , Isoxazoles/síntesis química , Isoxazoles/química , Modelos Moleculares , Estructura Molecular , Ratas , Receptores AMPA/metabolismo , Relación Estructura-Actividad

RESUMEN

[Sar9, Met(O2)11] termed Substance P (SP), is an effective and selective agonist for the neurokinin­1 (NK­1) receptors, which are synthetic peptides, similar in structure to SP. SP is an important neurotransmitter or neuromodulator mediated by neurokinin receptors, namely the SP receptor in the central nervous system. The excitatory effects induced by SP may be selectively inhibited by a neurokinin­1 receptor antagonist, such as SR140333B. It has been proposed that Parkinson's disease (PD) is primarily caused by the loss of trophic peptidergic neurotransmitter, possibly SP, which may lead to the degeneration of neurons. In previous studies, 1­methyl­4­phenylpyridinium (MPP+) has been frequently utilized to establish animal or cell models of PD. In the present study, to further investigate the effects of SP in PD, MPP+ was employed to investigate the promising anti­apoptotic effects of SP, and examine the underlying mechanisms of the pathology in the MES23.5 dopaminergic cell line. The results indicated that MPP+­triggered apoptosis was prevented by treatment with SP. SP treatment also decreased the MPP+­triggered Ca2+ influx, caspase­3 re­activity, reactive oxygen species production and mitochondrial membrane potential decrease. Treatment with MPP+ also induced phosphorylation of c­Jun N­terminal kinase and p38 mitogen­activated protein kinase. In addition, treatment with SP inhibited the MPP+­triggered neurotoxicity in MES23.5 cells. However, no changes were observed in SR140333B+SP+MPP+­treated MES23.5 cell lines. In conclusion, SP could protect the cells from MPP+­induced cytotoxicity by inhibiting the apoptosis via NK-1 receptors.

Asunto(s)

1-Metil-4-fenilpiridinio/toxicidad , Apoptosis/efectos de los fármacos , Fármacos Neuroprotectores/farmacología , Receptores de Neuroquinina-1/metabolismo , Sustancia P/farmacología , Animales , Calcio/metabolismo , Línea Celular , Supervivencia Celular/efectos de los fármacos , Fragmentación del ADN/efectos de los fármacos , Proteínas Quinasas JNK Activadas por Mitógenos/metabolismo , Potencial de la Membrana Mitocondrial/efectos de los fármacos , Ratones , Mitocondrias/metabolismo , Antagonistas del Receptor de Neuroquinina-1/farmacología , Fosforilación/efectos de los fármacos , Ratas , Especies Reactivas de Oxígeno/metabolismo , Receptores de Neuroquinina-1/química , Tropanos/farmacología , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo

RESUMEN

OBJECTIVE: To study the chemical compositions of Eucommia ulmoides. METHODS: The compounds were isolated and purified from Eucommia ulmoides by silica gel column chromatography, Sephadex LH-20, MPLC packed with MCI gel and semi-preparative HPLC. The structures of these compounds were established on the basis of spectral analyses (1H-NMR, 13C-NMR and MS). RESULTS: Thirteen compounds were obtained,and their structures were identified as betulin (1), syringin (2), pervoside A (3), glucosyringic acid (4), vanillic acid-beta-glucoside (5), geniposide acid (6), aucubin (7), geniposide (8), pinoresinol-4,4'-di-O-beta-D-glucopyranoside (9), syringaresinol di-O-beta-D-glucopyranoside (10), medioresinol di-O-beta-D-glucopyranoside (11), sucrose (12), and ethyl beta-glucopyranoside (13) on the basis of physical characteristics and spectral data. CONCLUSION: Compounds 3 - 5, 12 and 13 are isolated from this plant for the first itme.

Asunto(s)

Medicamentos Herbarios Chinos/química , Eucommiaceae/química , Plantas Medicinales/química , Benzoatos/química , Benzoatos/aislamiento & purificación , Cromatografía Líquida de Alta Presión/métodos , Ácidos Cumáricos/química , Ácidos Cumáricos/aislamiento & purificación , Medicamentos Herbarios Chinos/aislamiento & purificación , Glucósidos/química , Glucósidos/aislamiento & purificación , Estructura Molecular , Corteza de la Planta/química

RESUMEN

Three new labdane diterpenoids, calomacrins A-C (1-3), and a new diaryl butyrolactone-type lignan, calomacrol A (8), as well as four known labdane diterpenoids and six known lignans, were isolated from the twigs and leaves of Calocedrus macrolepis. Structures of the new compounds were elucidated on the basis of their spectroscopic methods, including 1D and 2D NMR techniques. Compounds 3-14 were evaluated for cytotoxicity against HL-60, SMMC-7721, A-549, MCF-7, and SW480 cell lines.

Asunto(s)

4-Butirolactona/análogos & derivados , Antineoplásicos Fitogénicos/aislamiento & purificación , Benzodioxoles/aislamiento & purificación , Cupressaceae/química , Diterpenos/aislamiento & purificación , 4-Butirolactona/química , 4-Butirolactona/aislamiento & purificación , Antineoplásicos Fitogénicos/química , Benzodioxoles/química , Diterpenos/química , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Células MCF-7