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1.
Microb Pathog ; 179: 106121, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-37086911

RESUMEN

Staphylococcus aureus is a common disease-causing bacterium that has developed resistances to a wide variety of antibiotics. This increasing antibiotic resistance has made management of these infections difficult. A better understanding of the general differences among clinical S. aureus strains beyond the well characterized resistance mechanisms may help in identifying new anti-microbial targets. This study aimed to identify and compare the general differences in protein profiles among clinical strains of S. aureus sensitive and resistant to methicillin. The proteomic profiles of five methicillin sensitive (MSSA) and five methicillin resistant (MRSA) S. aureus strains were analyzed by ultra-performance liquid chromatography-mass spectrometry. Protein identification was done using Progenesis QI for Proteomics and the UniProt S. aureus database. Proteins that play roles in virulence, metabolism, and protein synthesis were found to be present at different abundances between MSSA and MRSA (Data available via ProteomeXchange with identifier PXD021629). This study shows differences in protein profiles between antibiotic sensitive and antibiotic resistant clinical strains of S. aureus that may affect the resistance mechanism. Further research on these differences may identify new drug targets against methicillin resistant S. aureus strains.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Humanos , Meticilina , Resistencia a la Meticilina , Staphylococcus aureus , Proteómica , Antibacterianos/farmacología , Infecciones Estafilocócicas/microbiología , Pruebas de Sensibilidad Microbiana
2.
Sci Rep ; 12(1): 16159, 2022 09 28.
Artículo en Inglés | MEDLINE | ID: mdl-36171234

RESUMEN

Androgen receptor variant 7 (AR-V7) is an important biomarker to guide treatment options for castration-resistant prostate cancer (CRPC) patients. Its detectability in circulating tumour cells (CTCs) opens non-invasive diagnostic avenues. While detectable at the transcript level, AR-V7 protein detection in CTCs may add additional information and clinical relevance. The aim of this study was to compare commercially available anti-AR-V7 antibodies and establish reliable AR-V7 immunocytostaining applicable to CTCs from prostate cancer (PCa) patients. We compared seven AR-V7 antibodies by western blotting and immmunocytostaining using a set of PCa cell lines with known AR/AR-V7 status. The emerging best antibody was validated for detection of CRPC patient CTCs enriched by negative depletion of leucocytes. The anti-AR-V7 antibody, clone E308L emerged as the best antibody in regard to signal to noise ratio with a specific nuclear signal. Moreover, this antibody detects CRPC CTCs more efficiently compared to an antibody previously shown to detect AR-V7 CTCs. We have determined the best antibody for AR-V7 detection of CTCs, which will open future studies to correlate AR-V7 subcellular localization and potential co-localization with other proteins and cellular structures to patient outcomes.


Asunto(s)
Células Neoplásicas Circulantes , Neoplasias de la Próstata Resistentes a la Castración , Recuento de Células , Humanos , Masculino , Células Neoplásicas Circulantes/patología , Neoplasias de la Próstata Resistentes a la Castración/diagnóstico , Neoplasias de la Próstata Resistentes a la Castración/tratamiento farmacológico , Neoplasias de la Próstata Resistentes a la Castración/genética , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Receptores Androgénicos/genética , Receptores Androgénicos/metabolismo
3.
Infect Dis (Lond) ; 54(7): 497-507, 2022 07.
Artículo en Inglés | MEDLINE | ID: mdl-35277120

RESUMEN

BACKGROUND: Staphylococcus aureus is a common cause of infectious diseases in humans. It has become resistant to many antibacterial agents making management of infections difficult. A better understanding of differences among S. aureus strains that are sensitive and resistant to antibiotics may offer insights into the resistant phenotype and identify new antimicrobial targets. This study aimed at comparing general differences in lipid profiles among clinical strains of S. aureus sensitive and resistant to antibiotics. The cell wall thickness and cell surface charge were also compared. METHODS: Five methicillin sensitive (MSSA) and five methicillin resistant (MRSA) S. aureus strains were compared both individually and as MSSA and MRSA groups in the absence of antibiotics. Lipids were compared by ultra-performance liquid chromatography-mass spectrometry, cell wall thickness was compared by scanning transmission electron microscopy and whole-cell surface charge was compared using a cytochrome c binding assay. RESULTS: Twenty-two lipid species were identified in all ten strains of S. aureus. The abundance of three lipid species (two lysyl-phosphatidylglycerol and one diglycosyldiacylglycerol) were found to be different between MSSA and MRSA. Differences in cell wall thickness were identified between strains but not between MSSA and MRSA. No difference in whole-cell surface charge was observed between MSSA and MRSA. CONCLUSION: This study shows differences in membrane lipids between antibiotic sensitive and antibiotic resistant clinical strains of S aureus that may affect resistance mechanisms related to cell membrane structure and fluidity. Further research on these differences may identify new drug targets against resistant strains.


Asunto(s)
Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Antibacterianos/farmacología , Humanos , Lipidómica , Lípidos , Meticilina , Staphylococcus aureus Resistente a Meticilina/genética , Pruebas de Sensibilidad Microbiana , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/genética
4.
Molecules ; 26(23)2021 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-34885848

RESUMEN

Phospholipase A2 (PLA2) enzymes were first recognized as an enzyme activity class in 1961. The secreted (sPLA2) enzymes were the first of the five major classes of human PLA2s to be identified and now number nine catalytically-active structurally homologous proteins. The best-studied of these, group IIA sPLA2, has a clear role in the physiological response to infection and minor injury and acts as an amplifier of pathological inflammation. The enzyme has been a target for anti-inflammatory drug development in multiple disorders where chronic inflammation is a driver of pathology since its cloning in 1989. Despite intensive effort, no clinically approved medicines targeting the enzyme activity have yet been developed. This review catalogues the major discoveries in the human group IIA sPLA2 field, focusing on features of enzyme function that may explain this lack of success and discusses future research that may assist in realizing the potential benefit of targeting this enzyme. Functionally-selective inhibitors together with isoform-selective inhibitors are necessary to limit the apparent toxicity of previous drugs. There is also a need to define the relevance of the catalytic function of hGIIA to human inflammatory pathology relative to its recently-discovered catalysis-independent function.


Asunto(s)
Fosfolipasas A2 Grupo II/metabolismo , Desarrollo de Medicamentos , Fosfolipasas A2 Grupo II/antagonistas & inhibidores , Fosfolipasas A2 Grupo II/farmacología , Humanos , Neoplasias/diagnóstico , Neoplasias/enzimología , Pronóstico
5.
Exp Eye Res ; 202: 108317, 2021 01.
Artículo en Inglés | MEDLINE | ID: mdl-33130031

RESUMEN

Here we describe a modified method for harvesting tens-of-millions of human lens epithelial-like cells from differentiated pluripotent stem cell cultures. To assess the utility of this method, we analysed the lens cell population via: light microscopy; single cell RNA-sequencing and gene ontology analyses; formation of light-focusing micro-lenses; mass spectrometry; and electron microscopy. Both individually and collectively, the data indicate this simplified harvesting method provides a large-scale source of stem cell-derived lens cells and micro-lenses for investigating human lens and cataract formation.


Asunto(s)
Separación Celular/métodos , Células Epiteliales/citología , Cristalino/citología , Células Madre Pluripotentes/citología , Diferenciación Celular , Células Epiteliales/metabolismo , Humanos , Cristalino/metabolismo , Espectrometría de Masas , Microscopía , Microscopía Electrónica , Células Madre Pluripotentes/metabolismo , Receptores Huérfanos Similares al Receptor Tirosina Quinasa/metabolismo , Análisis de Secuencia de ARN
6.
J Clin Med ; 9(7)2020 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-32650561

RESUMEN

Non-erosive reflux disease (NERD) and esophageal adenocarcinoma (EAC) are often regarded as bookends in the gastroesophageal reflux disease spectrum. However, there is limited clinical evidence to support this disease paradigm while the underlying mechanisms of disease progression remain unclear. In this study, we used 16S rRNA sequencing and mass-spectrometer-based proteomics to characterize the esophageal microbiota and host mucosa proteome, respectively. A total of 70 participants from four patient groups (NERD, reflux esophagitis, Barrett's esophagus, and EAC) and a control group were analyzed. Our results showed a unique NERD microbiota composition, distinct to control and other groups. We speculate that an increase in sulfate-reducing Proteobacteria and Bacteroidetes along with hydrogen producer Dorea are associated with a mechanistic role in visceral hypersensitivity. We also observed a distinct EAC microbiota consisting of a high abundance of lactic acid-producing bacteria (Staphylococcus, Lactobacillus, Bifidobacterium, and Streptococcus), which may contribute towards carcinogenesis through dysregulated lactate metabolism. This study suggests the close relationship between esophageal mucosal microbiota and the appearance of pathologies of this organ.

7.
ACS Comb Sci ; 22(5): 255-267, 2020 05 11.
Artículo en Inglés | MEDLINE | ID: mdl-32283009

RESUMEN

Through a screen of over one hundred and 30 permutations of reaction temperatures, solvents, carbodiimide resins, and carbodiimide molar equivalences, in the presence, absence, or combination of diisopropylamine and benzotriazole additives, a convenient and first reported carbodiimide polymer-assisted flow approach to effect amide coupling and lactamization was developed. The protocol entails injecting a single solution (1:9 dimethylformamide: dichloromethane) containing a carboxylic acid and an amine or linear peptide sequence into a continuous stream of dichloromethane. The protocol remained viable in the absence of base, did not require carboxylate preactivation which, and in concert with minimal workup requirements, enabled the isolation of products in high yields. Compared to the utilization of untethered carbodiimide reagents, the flow procedure was also observed to provide a degree of racemization safety.


Asunto(s)
Amidas/química , Amidas/síntesis química , Carbodiimidas/química , Microondas , Estructura Molecular
8.
J Biol Inorg Chem ; 25(3): 429-440, 2020 05.
Artículo en Inglés | MEDLINE | ID: mdl-32219553

RESUMEN

The binding interactions of a series of square-planar platinum(II)-phenanthroline complexes of the type [Pt(PL)(AL)]2+ [where PL = variously methyl-substituted 1,10-phenanthroline (phen) and AL = ethane-1,2-diamine (en)] were assessed with a G-quadruplex DNA (5'-TTG GGG GT-3', G4DNA) and a double-stranded DNA (5'-CGC GAA TTC GCG-3', dsDNA) sequence by ESI-MS. The results indicate a strong correlation between G4DNA affinity and increasing phenanthroline methyl substitution. Circular dichroism (CD) spectroscopy and molecular docking studies also support the finding that increased substitution of the phenanthroline ligand increased selectivity for G4DNA. ESI-MS was used to probe the interaction of a range of square-planar Pt(II)-phenanthroline complexes with double-stranded and G-quadruplex DNA.


Asunto(s)
Complejos de Coordinación/química , ADN/química , Teoría Funcional de la Densidad , Simulación del Acoplamiento Molecular , Fenantrolinas/química , Platino (Metal)/química , Dicroismo Circular , ADN/aislamiento & purificación , G-Cuádruplex , Estructura Molecular , Espectrometría de Masa por Ionización de Electrospray
9.
Anal Biochem ; 573: 51-66, 2019 05 15.
Artículo en Inglés | MEDLINE | ID: mdl-30796906

RESUMEN

Glyoxal (GO) and methylglyoxal (MGO) are two important biomarkers in diabetes. Analytical methods for determination of GO and MGO in serum samples are either HPLC with UV-Vis (low sensitivity) or MS/MS (expensive) detection. These disadvantages have hampered the introduction of these biomarkers as a routine analyte for diabetes diagnostics into the clinical laboratory. In this study, we introduce a UHPLC method with fluorescence detection for the measurement of GO and MGO in serum samples by pre-column derivatization at neutral pH with 5, 6-diamino-2,4-dihydroxypyrimidine sulfate (DDP) to form lumazines. The method was validated as per FDA guidelines. Using this method, we have determined GO and MGO in a variety of animal serum samples, and for example, determined the GO and MGO concentration in adult bovine serum to be 852 ±â€¯27 and 192 ±â€¯10 nmol/L, respectively. In human serum, GO and MGO levels in non-diabetic subjects (n = 14) were determined to be 154 ±â€¯88 and 98 ±â€¯27 nmol/L, and in serum samples from subjects with diabetes (n = 14) 244 ±â€¯137 and 190 ±â€¯68 nmol/L, respectively. In addition, interference studies showed that physiological serum components did not lead to an artificial increase in the levels of GO and MGO.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Colorantes Fluorescentes/química , Glioxal/sangre , Piruvaldehído/sangre , Anciano , Anciano de 80 o más Años , Animales , Calibración , Cromatografía Líquida de Alta Presión/normas , Diabetes Mellitus/patología , Femenino , Glioxal/química , Glioxal/normas , Humanos , Concentración de Iones de Hidrógeno , Límite de Detección , Masculino , Espectrometría de Masas , Persona de Mediana Edad , Pteridinas/química , Piruvaldehído/química , Piruvaldehído/normas , Reproducibilidad de los Resultados
10.
Development ; 145(1)2018 01 09.
Artículo en Inglés | MEDLINE | ID: mdl-29217756

RESUMEN

Cataracts cause vision loss and blindness by impairing the ability of the ocular lens to focus light onto the retina. Various cataract risk factors have been identified, including drug treatments, age, smoking and diabetes. However, the molecular events responsible for these different forms of cataract are ill-defined, and the advent of modern cataract surgery in the 1960s virtually eliminated access to human lenses for research. Here, we demonstrate large-scale production of light-focusing human micro-lenses from spheroidal masses of human lens epithelial cells purified from differentiating pluripotent stem cells. The purified lens cells and micro-lenses display similar morphology, cellular arrangement, mRNA expression and protein expression to human lens cells and lenses. Exposing the micro-lenses to the emergent cystic fibrosis drug Vx-770 reduces micro-lens transparency and focusing ability. These human micro-lenses provide a powerful and large-scale platform for defining molecular disease mechanisms caused by cataract risk factors, for anti-cataract drug screening and for clinically relevant toxicity assays.


Asunto(s)
Aminofenoles/efectos adversos , Catarata/inducido químicamente , Catarata/metabolismo , Cristalino/metabolismo , Modelos Biológicos , Células Madre Pluripotentes/metabolismo , Quinolonas/efectos adversos , Aminofenoles/farmacología , Catarata/patología , Humanos , Cristalino/patología , Células Madre Pluripotentes/patología , Quinolonas/farmacología
11.
Anal Chem ; 89(22): 12276-12283, 2017 11 21.
Artículo en Inglés | MEDLINE | ID: mdl-29057649

RESUMEN

Measurement of dopamine (DA) release in the retina allows the interrogation of the complex neural circuits within this tissue. A number of previous methods have been used to quantify this neuromodulator, the most common of which is HPLC with electrochemical detection (HPLC-ECD). However, this technique can produce significant concentration uncertainties. In this present study, we report a sensitive and accurate UHPLC-MS/MS method for the quantification of DA and its primary metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in mouse retina. Internal standards DA-d4 and DOPAC-d5 result in standard curve linearity for DA from 0.05-100 ng/mL (LOD = 6 pg/mL) and DOPAC from 0.5-100 ng/mL (LOD = 162 pg/mL). A systematic study of tissue extraction conditions reveals that the use of formic acid (1%), in place of the more commonly used perchloric acid, combined with 0.5 mM ascorbic acid prevents significant oxidation of the analytes. When the method is applied to mouse retinae a significant increase in the DOPAC/DA ratio is observed following in vivo light stimulation. We additionally examined the effect of anesthesia on DA and DOPAC levels in the retina in vivo and find that basal dark-adapted concentrations are not affected. Light caused a similar increase in DOPAC/DA ratio but interindividual variation was significantly reduced. Together, we systematically describe the ideal conditions to accurately and reliably measure DA turnover in the mammalian retina.


Asunto(s)
Dopamina/análisis , Técnicas Electroquímicas , Retina/química , Animales , Cromatografía Líquida de Alta Presión , Dopamina/metabolismo , Femenino , Masculino , Ratones , Ratones Endogámicos C57BL , Estructura Molecular , Retina/metabolismo , Espectrometría de Masas en Tándem
12.
ChemMedChem ; 12(2): 130-145, 2017 01 20.
Artículo en Inglés | MEDLINE | ID: mdl-27921386

RESUMEN

A series of 28 norcantharidin (NorC)-inspired analogues were accessed via a robust two-step Ugi intramolecular Diels-Alder (IMDA) sequence. Four analogues displayed whole-cell cytotoxicity equipotent to that of NorC and cisplatin against a number of cancer cell lines and a normal breast cell line (MCF10A). Notably, (3S,3aS,6R)-2-benzyl-7-methyl-N-(naphthalen-2-yl)-1-oxo-1,2,3,6-tetrahydro-3a,6-epoxyisoindole-3-carboxamide (trans-27) displayed superior whole-cell activity against breast (MCF-7, GI50 =2.9 µm) and colon (HT29, GI50 =6.4 µm) cancer cell lines relative to the control (cisplatin), which elicited respective GI50 values of 6.5 and 11.3 µm against the aforementioned cell lines. This analogue also displayed improved activity relative to NorC across the breast (MCF-7, GI50 =2.9 µm; NorC GI50 =7.5 µm), ovarian (A2780, GI50 =2.2 µm; NorC GI50 =4.4 µm), and neuroblastoma (BE2-C, GI50 =2.2 µm; NorC GI50 =3.7 µm) cancer cell lines. Structure-activity relationship (SAR) investigations demonstrated that retention of sp2 hybridized connections within the tetrahydroepoxyisoindole carboxamide scaffold is crucial, as aromatization to a phenolic functionality decreased activity, whereas removal of a single olefin bond abolished cytotoxicity. Nonetheless, with respect to the latter, use of crotonic acid as opposed 2-butynoic acid in the Ugi-IMDA sequence imparted a significant improvement to diastereoselectivity, with the cis/trans isomer ratio shifting from ≈1:1.2 to ≈0.5:9.5.


Asunto(s)
Amidas/química , Antineoplásicos/química , Compuestos Bicíclicos Heterocíclicos con Puentes/química , Antineoplásicos/síntesis química , Antineoplásicos/toxicidad , Compuestos Bicíclicos Heterocíclicos con Puentes/síntesis química , Compuestos Bicíclicos Heterocíclicos con Puentes/toxicidad , Línea Celular Tumoral , Cristalografía por Rayos X , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Isoindoles/química , Isomerismo , Conformación Molecular , Relación Estructura-Actividad
13.
Dalton Trans ; 45(23): 9407-11, 2016 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-27227419

RESUMEN

We present the synthesis and characterization of a unique, slightly distorted square prismatic, box-like coordination cage of type [Cu6Dy8L8(MeOH)8(H2O)6](NO3)12·χsolvent obtained via the supramolecular assembly between a non-centrosymmetric Dy(iii) metalloligand and Cu(ii) nitrate. Magnetic susceptibility measurements indicate that the complex behaves as a single-molecule magnet.

14.
Food Funct ; 6(3): 910-9, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25629927

RESUMEN

Chronic inflammation is a contributing factor in many age-related diseases. In a previous study, we have shown that Sri Lankan cinnamon (C. zeylanicum) was one of the most potent anti-inflammatory foods out of 115 foods tested. However, knowledge about the exact nature of the anti-inflammatory compounds and their distribution in the two major cinnamon species used for human consumption is limited. The aim of this investigation was to determine the anti-inflammatory activity of C. zeylanicum and C. cassia and elucidate their main phytochemical compounds. When extracts were tested in LPS and IFN-γ activated RAW 264.7 macrophages, most of the anti-inflammatory activity, measured by down-regulation of nitric oxide and TNF-α production, was observed in the organic extracts. The most abundant compounds in these extracts were E-cinnamaldehyde and o-methoxycinnamaldehyde. The highest concentration of E-cinnamaldehyde was found in the DCM extract of C. zeylanicum or C. cassia (31 and 34 mg g(-1) of cinnamon, respectively). When these and other constituents were tested for their anti-inflammatory activity in RAW 264.7 and J774A.1 macrophages, the most potent compounds were E-cinnamaldehyde and o-methoxycinnamaldehyde, which exhibited IC50 values for NO with RAW 264.7 cells of 55 ± 9 µM (7.3 ± 1.2 µg mL(-1)) and 35 ± 9 µM (5.7 ± 1.5 µg mL(-1)), respectively; and IC50 values for TNF-α of 63 ± 9 µM (8.3 ± 1.2 µg mL(-1)) and 78 ± 16 µM (12.6 ± 2.6 µg mL(-1)), respectively. If therapeutic concentrations can be achieved in target tissues, cinnamon and its components may be useful in the treatment of age-related inflammatory conditions.


Asunto(s)
Acroleína/análogos & derivados , Antiinflamatorios no Esteroideos/aislamiento & purificación , Cinnamomum aromaticum/química , Cinnamomum zeylanicum/química , Suplementos Dietéticos , Macrófagos/metabolismo , Acroleína/análisis , Acroleína/química , Acroleína/aislamiento & purificación , Acroleína/metabolismo , Animales , Antiinflamatorios no Esteroideos/análisis , Antiinflamatorios no Esteroideos/química , Antiinflamatorios no Esteroideos/metabolismo , Línea Celular , Cinnamomum aromaticum/crecimiento & desarrollo , Suplementos Dietéticos/análisis , Etnofarmacología , Activación de Macrófagos , Macrófagos/inmunología , Medicina Tradicional , Ratones , Estructura Molecular , Óxido Nítrico/antagonistas & inhibidores , Óxido Nítrico/metabolismo , Corteza de la Planta/química , Corteza de la Planta/crecimiento & desarrollo , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Extractos Vegetales/metabolismo , Sri Lanka , Estereoisomerismo , Factor de Necrosis Tumoral alfa/antagonistas & inhibidores , Factor de Necrosis Tumoral alfa/metabolismo
15.
Acta Biomater ; 14: 33-42, 2015 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-25484333

RESUMEN

A novel water-dispersible conducting polymer analogous to poly(3,4-dioxythiophene):polystyrene sulfonate (PEDOT:PSS) has been chemically synthesized in a single reaction in high yield. PEDOT:DS, a new member of the polythiophene family, is composed of a complex between PEDOT and the sulfonated polysaccharide polyanion dextran sulfate. Drop-cast films of aqueous suspensions of the material display a native conductivity of up to 7 ± 1 S cm(-1), increasing to 20 ± 2 S cm(-1) after treatment with ethylene glycol and thermal annealing. Mass ratios of the precursors NaDS and EDOT were varied from 5:1 to 2:1 and a decrease in the NaDS:EDOT ratio produces tougher, less hygroscopic films of higher conductivity. Ultraviolet-visible spectroelectrochemistry yields spectra typical of PEDOT complexes. Cyclic voltammetry reveals that PEDOT:DS is electrochemically active from -1.0 to 0.8 V vs. Ag/Ag(+) in acetonitrile, with similar characteristics to PEDOT:PSS. Water dispersions of PEDOT:DS are successfully processed by drop casting, spray coating, inkjet printing and extrusion printing. Furthermore, laser etching of dried films allows the creation of patterns with excellent definition. To assess the cytotoxicity of PEDOT:DS, L-929 cells were cultured with a polymer complex concentration range of 0.002 to 0.2 g l(-1) in cell culture medium. No significant difference is found between the proliferation rates of L-929 cells exposed to PEDOT:DS and those in plain medium after 96h. However, PEDOT:PSS shows around 25% less cell growth after 4 days, even at the lowest concentration. Taken together, these results suggest PEDOT:DS has exceptional potential as an electromaterial for the biointerface.


Asunto(s)
Biopolímeros/farmacología , Compuestos Bicíclicos Heterocíclicos con Puentes/farmacología , Sulfato de Dextran/farmacología , Conductividad Eléctrica , Compuestos Orgánicos/farmacología , Polímeros/farmacología , Animales , Compuestos Bicíclicos Heterocíclicos con Puentes/síntesis química , Compuestos Bicíclicos Heterocíclicos con Puentes/química , Línea Celular , Proliferación Celular/efectos de los fármacos , Sulfato de Dextran/síntesis química , Sulfato de Dextran/química , Técnicas Electroquímicas , Ratones , Microscopía Electrónica de Rastreo , Oxidación-Reducción , Tamaño de la Partícula , Polímeros/síntesis química , Polímeros/química , Análisis Espectral , Temperatura
16.
Org Biomol Chem ; 12(47): 9562-71, 2014 Dec 21.
Artículo en Inglés | MEDLINE | ID: mdl-25333944

RESUMEN

Suzuki cross-couplings of 5-formyl-2-furanylboronic acid with activated or neutral aryl bromides were performed under continuous flow conditions in the presence of (Bu)4N(+)F(-) and the immobilised t-butyl based palladium catalyst CatCart™ FC1032™. Deactivated aryl bromides and activated aryl chlorides were cross-coupled with 5-formyl-2-furanylboronic in the presence of (Bu)4N(+)OAc(-) using the bis-triphenylphosphine CatCart™ PdCl2(PPh3)2-DVB. Initial evidence indicates the latter method may serve as a universal approach to conduct Suzuki cross-couplings with the protocol successfully employed in the synthesis of the current gold standard Hedgehog pathway inhibitor LDE225.


Asunto(s)
Compuestos de Bifenilo/síntesis química , Bromuros/química , Furanos/química , Paladio/química , Piridinas/síntesis química , Ácidos Borónicos/síntesis química , Ácidos Borónicos/química , Bromuros/síntesis química , Catálisis , Furanos/síntesis química , Modelos Moleculares
17.
Phys Chem Chem Phys ; 14(48): 16719-30, 2012 Dec 28.
Artículo en Inglés | MEDLINE | ID: mdl-23138779

RESUMEN

The phenylperoxyl radical has long been accepted as a critical intermediate in the oxidation of benzene and an archetype for arylperoxyl radicals in combustion and atmospheric chemistry. Despite being central to many contemporary mechanisms underpinning these chemistries, reports of the direct detection or isolation of phenylperoxyl radicals are rare and there is little experimental evidence connecting this intermediate with expected product channels. We have prepared and isolated two charge-tagged phenyl radical models in the gas phase [i.e., 4-(N,N,N-trimethylammonium)phenyl radical cation and 4-carboxylatophenyl radical anion] and observed their reactions with dioxygen by ion-trap mass spectrometry. Measured reaction rates show good agreement with prior reports for the neutral system (k(2)[(Me(3)N(+))C(6)H(4)˙ + O(2)] = 2.8 × 10(-11) cm(3) molecule(-1) s(-1), Φ = 4.9%; k(2)[((-)O(2)C)C(6)H(4)˙ + O(2)] = 5.4 × 10(-11) cm(3) molecule(-1) s(-1), Φ = 9.2%) and the resulting mass spectra provide unequivocal evidence for the formation of phenylperoxyl radicals. Collisional activation of isolated phenylperoxyl radicals reveals unimolecular decomposition by three pathways: (i) loss of dioxygen to reform the initial phenyl radical; (ii) loss of atomic oxygen yielding a phenoxyl radical; and (iii) ejection of the formyl radical to give cyclopentadienone. Stable isotope labeling confirms these assignments. Quantum chemical calculations for both charge-tagged and neutral phenylperoxyl radicals confirm that loss of formyl radical is accessible both thermodynamically and entropically and competitive with direct loss of both hydrogen atom and carbon dioxide.

18.
J Phys Chem A ; 114(3): 1446-56, 2010 Jan 28.
Artículo en Inglés | MEDLINE | ID: mdl-20039627

RESUMEN

Alkylperoxyl radicals are intermediates in the oxidation of hydrocarbons. The reactive nature of these intermediates, however, has made them elusive to direct observation and isolation. We have employed ion trap mass spectrometry to synthesize and characterize 4-carboxylatocyclohexyl radical anions (*C(6)H(10)-CO(2)(-)) and observe their reactivity in the presence of dioxygen. The resulting reaction is facile (k = 1.8 x 10(-10) cm(3) molecule(-1) s(-1) or 30% of calculated collision rate) and results in (i) the addition of O(2) to form stabilized 4-carboxylatocyclohexylperoxyl radical anions (*OO-C(6)H(10)-CO(2)(-)), providing the first direct observation of a cyclohexylperoxyl radical, and (ii) elimination of HO(2)* and HO* radicals consistent with recent laser-induced fluorescence studies of the reaction of neutral cyclohexyl radicals with O(2). Electronic structure calculations at the B3LYP/6-31+G(d) level of theory reveal viable pathways for the observed reactions showing that formation of the peroxyl radical is exothermic by 37 kcal mol(-1) with subsequent transition states as low as -6.6 kcal mol(-1) (formation of HO(2)*) and -9.1 kcal mol(-1) (formation of HO*) with respect to the entrance channel. The combined computational and experimental data suggest that the structures of the reaction products correspond to cyclohexenes and epoxides from HO(2)* and HO* loss, respectively, while alternative pathways leading to cyclohexanone or ring-opened isomers are not observed. Activation of the charged peroxyl radical *OO-C(6)H(10)-CO(2)(-) by collision induced dissociation also results in the loss of HO(2)* and HO* radicals confirming that these products are directly connected to the peroxyl radical intermediate.

19.
Dalton Trans ; (3): 504-13, 2009 Jan 21.
Artículo en Inglés | MEDLINE | ID: mdl-19122908

RESUMEN

Electrospray ionisation mass spectrometry, absorption spectrophotometry and circular dichroism spectroscopy were used to investigate the binding of a series of nickel complexes with the general formula [Ni(phen)2L]2+ (L = phen, dpq, dpqC and dppz) to a double stranded DNA hexadecamer. In addition, the binding of the complexes to pUC9 negatively supercoiled plasmid DNA was examined using gel electrophoresis, and their ability to inhibit DNA transcription was measured. Each of the above techniques showed that DNA binding strengthened as the size of the unique ligand L was increased. Comparison of the above results with those obtained previously, and presented here for the first time for the analogous series of ruthenium complexes [Ru(phen)2L]2+, showed that changing the metal ion from nickel to ruthenium consistently resulted in significant increases in DNA binding affinity.


Asunto(s)
ADN/química , Metales/química , Química/métodos , Dicroismo Circular , Cristalografía por Rayos X/métodos , Iones , Cinética , Espectrometría de Masas/métodos , Modelos Químicos , Estructura Molecular , Níquel/química , Rutenio/química , Espectrometría de Masa por Ionización de Electrospray/métodos , Espectrofotometría/métodos , Transcripción Genética
20.
Anal Chem ; 80(1): 303-11, 2008 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-18062677

RESUMEN

Ions formed from lipids during electrospray ionization of crude lipid extracts have been mass-selected within a quadrupole linear ion trap mass spectrometer and allowed to react with ozone vapor. Gas-phase ion-molecule reactions between unsaturated lipid ions and ozone are found to yield two primary product ions for each carbon-carbon double bond within the molecule. The mass-to-charge ratios of these chemically induced fragments are diagnostic of the position of unsaturation within the precursor ion. This novel analytical technique, dubbed ozone-induced dissociation (OzID), can be applied both in series and in parallel with conventional collision-induced dissociation (CID) to provide near-complete structural assignment of unknown lipids within complex mixtures without prior fractionation or derivatization. In this study, OzID is applied to a suite of complex lipid extracts from sources including human lens, bovine kidney, and commercial olive oil, thus demonstrating the technique to be applicable to a broad range of lipid classes including both neutral and acidic glycerophospholipids, sphingomyelins, and triacylglycerols. Gas-phase ozonolysis reactions are also observed with different types of precursor ions including [M+H]+, [M+Li]+, [M+Na]+, and [M-H]-: in each case yielding fragmentation data that allow double bond position to be unambiguously assigned. Within the human lens lipid extract, three sphingomyelin regioisomers, namely SM(d18:0/15Z-24:1), SM(d18:0/17Z-24:1), and SM(d18:0/19Z-24:1), and a novel phosphatidylethanolamine alkyl ether, GPEtn(11Z-18:1e/9Z-18:1), are identified using a combination of CID and OzID. These discoveries demonstrate that lipid identification based on CID alone belies the natural structural diversity in lipid biochemistry and illustrate the potential of OzID as a complementary approach within automated, high-throughput lipid analysis protocols.


Asunto(s)
Aniones/química , Cationes/química , Lípidos/química , Ozono/química , Espectrometría de Masa por Ionización de Electrospray , Animales , Bovinos , Glicerofosfolípidos/análisis , Glicerofosfolípidos/química , Humanos , Riñón/química , Cinética , Cristalino/química , Lípidos/análisis , Fosfatidilcolinas/análisis , Fosfatidilcolinas/química , Triglicéridos/análisis , Volatilización
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