Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Resultados 1 - 20 de 169
Filtrar
1.
J Immunol ; 205(8): 2077-2090, 2020 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-32929040

RESUMEN

Previously, we discovered that influenza-generated CD4 effectors must recognize cognate Ag at a defined effector checkpoint to become memory cells. Ag recognition was also required for efficient protection against lethal influenza infection. To extend these findings, we investigated if vaccine-generated effectors would have the same requirement. We compared live infection with influenza to an inactivated whole influenza vaccine. Live infection provided strong, long-lasting Ag presentation that persisted through the effector phase. It stimulated effector generation, long-lived CD4 memory generation, and robust generation of Ab-producing B cells. In contrast, immunization with an inactivated virus vaccine, even when enhanced by additional Ag-pulsed APC, presented Ag for 3 d or less and generated few CD4 memory cells or long-lived Ab-producing B cells. To test if checkpoint Ag addition would enhance this vaccine response, we immunized mice with inactivated vaccine and injected Ag-pulsed activated APC at the predicted effector checkpoint to provide Ag presentation to the effector CD4 T cells. This enhanced generation of CD4 memory, especially tissue-resident memory in the lung, long-lived bone marrow Ab-secreting cells, and influenza-specific IgG Ab. All responses increased as we increased the density of peptide Ag on the APC to high levels. This suggests that CD4 effectors induced by inactivated vaccine require high levels of cognate Ag recognition at the effector checkpoint to most efficiently become memory cells. Thus, we suggest that nonlive vaccines will need to provide high levels of Ag recognition throughout the effector checkpoint to optimize CD4 memory generation.


Asunto(s)
Anticuerpos Antivirales/inmunología , Formación de Anticuerpos , Antígenos Virales/inmunología , Linfocitos T CD4-Positivos/inmunología , Memoria Inmunológica , Vacunas contra la Influenza/inmunología , Pulmón/inmunología , Animales , Anticuerpos Antivirales/genética , Antígenos Virales/genética , Femenino , Vacunas contra la Influenza/genética , Masculino , Ratones Endogámicos BALB C , Ratones Transgénicos , omegacloroacetofenona
2.
Nanomedicine ; 21: 102076, 2019 10.
Artículo en Inglés | MEDLINE | ID: mdl-31394261

RESUMEN

Pretargeting is an increasingly explored strategy to improve nanoparticle targeting, in which pretargeting molecules that bind both selected epitopes on target cells and nanocarriers are first administered, followed by the drug-loaded nanocarriers. Bispecific antibodies (bsAb) represent a promising class of pretargeting molecules, but how different bsAb formats may impact the efficiency of pretargeting remains poorly understood, in particular Fab valency and Fc receptor (FcR)-binding of bsAb. We found the tetravalent bsAb markedly enhanced PEGylated nanoparticle binding to target HER2+ cells relative to the bivalent bsAb in vitro. Pretargeting with tetravalent bsAb with abrogated FcR binding increased tumor accumulation of PEGylated liposomal doxorubicin (PLD) 3-fold compared to passively targeted PLD alone, and 5-fold vs pretargeting with tetravalent bsAb with normal FcR binding in vivo. Our work demonstrates that multivalency and elimination of FcRn recycling are both important features of pretargeting molecules, and further supports pretargeting as a promising nanoparticle delivery strategy.


Asunto(s)
Anticuerpos Biespecíficos , Antineoplásicos Inmunológicos , Portadores de Fármacos , Neoplasias Experimentales , Polietilenglicoles , Receptor ErbB-2/antagonistas & inhibidores , Animales , Anticuerpos Biespecíficos/química , Anticuerpos Biespecíficos/farmacología , Antineoplásicos Inmunológicos/química , Antineoplásicos Inmunológicos/farmacología , Línea Celular Tumoral , Portadores de Fármacos/química , Portadores de Fármacos/farmacología , Femenino , Humanos , Ratones Desnudos , Neoplasias Experimentales/tratamiento farmacológico , Neoplasias Experimentales/metabolismo , Neoplasias Experimentales/patología , Polietilenglicoles/química , Polietilenglicoles/farmacología , Ensayos Antitumor por Modelo de Xenoinjerto , omegacloroacetofenona
3.
Immunopharmacol Immunotoxicol ; 41(2): 277-284, 2019 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-31084401

RESUMEN

Objectives: Gouty arthritis is caused by the deposition of monosodium urate (MSU) crystals in joints, which is associated with the rise of serum urate content. This study aims to investigate the therapeutic effect of Madecassoside on gouty arthritis and hyperuricemia. Methods: DBA/1 mice were intradermally injected with MSU to stimulate joint inflammation or intraperitoneally injected with MSU to trigger peritonitis. Moreover, ICR mice were exposed to potassium oxonate to stimulate hyperuricemia. Results: Madecassoside repressed MSU-triggered pad swelling, joint 99mTc uptake, and joint inflammation in DBA/1 mice with gouty arthritis. Neutrophil infiltration and IL-1ß & IL-6 & MCP-1 secretion was also alleviated in lavage fluids from DBA/1 mice with peritonitis due to Madecassoside treatment. Furthermore, Madecassoside decreased MSU-induced neutrophil cytosolic factor 1, caspase-1 and NLRP3 expression in mice with peritoneal inflammation. In hyperuricemic mice, Madecassoside improved renal dysfunction. Serum uric acid, BUN, and creatinine were down-regulated by Madecassoside. Conclusion: These findings indicate that Madecassoside has potential to ameliorate inflammation in both acute gouty arthritis model and peritonitis model, probably via regulating IL-1ß and NLRP3 expression. Practical point: Madecassoside also exhibited a urate-lowering effect and a renal protective effect in hyperuricemic mice.


Asunto(s)
Antiinflamatorios/farmacología , Artritis Gotosa/tratamiento farmacológico , Hiperuricemia/tratamiento farmacológico , Proteína con Dominio Pirina 3 de la Familia NLR/inmunología , Triterpenos/farmacología , Animales , Artritis Gotosa/inducido químicamente , Artritis Gotosa/inmunología , Citocinas/inmunología , Hiperuricemia/inducido químicamente , Hiperuricemia/inmunología , Hiperuricemia/patología , Inflamación/inducido químicamente , Inflamación/tratamiento farmacológico , Inflamación/inmunología , Inflamación/patología , Masculino , Ratones Endogámicos ICR , Infiltración Neutrófila/efectos de los fármacos , Neutrófilos/inmunología , Neutrófilos/patología , Peritonitis/inducido químicamente , Peritonitis/inmunología , Peritonitis/patología , Ácido Úrico/toxicidad , omegacloroacetofenona
4.
J Cell Biochem ; 118(10): 3249-3259, 2017 10.
Artículo en Inglés | MEDLINE | ID: mdl-28262979

RESUMEN

Saturated fatty acids (SFA) and their toxic metabolites contribute to hepatocyte lipotoxicity in nonalcoholic steatohepatitis (NASH). We previously reported that hepatocytes, under lipotoxic stress, express the potent macrophage chemotactic ligand C-X-C motif chemokine 10 (CXCL10), and release CXCL10-enriched extracellular vesicles (EV) by a mixed lineage kinase (MLK) 3-dependent mechanism. In the current study, we sought to examine the signaling pathway responsible for CXCL10 induction during hepatocyte lipotoxicity. Here, we demonstrate a role for signal transducer and activator of transcription (STAT) 1 in regulating CXCL10 expression. Huh7 and HepG2 cells were treated with lysophosphatidylcholine (LPC), the toxic metabolite of the SFA palmitate. In LPC-treated hepatocytes, CXCL10 induction is mediated by a mitogen activated protein kinase (MAPK) signaling cascade consisting of a relay kinase module of MLK3, MKK3/6, and p38. P38 in turn induces STAT1 Ser727 phosphorylation and CXCL10 upregulation in hepatocytes, which is reduced by genetic or pharmacological inhibition of this MAPK signaling cascade. The binding and activity of STAT1 at the CXCL10 gene promoter were identified by chromatin immunoprecipitation and luciferase gene expression assays. Promoter activation was attenuated by MLK3/STAT1 inhibition or by deletion of the consensus STAT1 binding sites within the CXCL10 promoter. In lipotoxic hepatocytes, MLK3 activates a MAPK signaling cascade, resulting in the activating phosphorylation of STAT1, and CXCL10 transcriptional upregulation. Hence, this kinase relay module and/or STAT1 inhibition may serve as a therapeutic target to reduce CXCL10 release, thereby attenuating NASH pathogenesis. J. Cell. Biochem. 118: 3249-3259, 2017. © 2017 Wiley Periodicals, Inc.


Asunto(s)
Quimiocina CXCL10/metabolismo , Hepatocitos/metabolismo , Quinasas Quinasa Quinasa PAM/metabolismo , Enfermedad del Hígado Graso no Alcohólico/metabolismo , Factor de Transcripción STAT1/metabolismo , Células Hep G2 , Hepatocitos/patología , Humanos , Lisofosfatidilcolinas/toxicidad , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Enfermedad del Hígado Graso no Alcohólico/inducido químicamente , Enfermedad del Hígado Graso no Alcohólico/patología , Ácido Palmítico/toxicidad , omegacloroacetofenona , Proteina Quinasa Quinasa Quinasa 11 Activada por Mitógeno
5.
Environ Sci Technol ; 50(4): 1868-76, 2016 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-26814150

RESUMEN

Increasing recognition that abiotic natural attenuation (NA) of chlorinated solvents can be important has created demand for improved methods to characterize the redox properties of the aquifer materials that are responsible for abiotic NA. This study explores one promising approach: using chemical reactivity probes (CRPs) to characterize the thermodynamic and kinetic aspects of contaminant reduction by reducing iron minerals. Assays of thermodynamic CRPs were developed to determine the reduction potentials (ECRP) of suspended minerals by spectrophotometric determination of equilibrium CRP speciation and calculations using the Nernst equation. ECRP varied as expected with mineral type, mineral loading, and Fe(II) concentration. Comparison of ECRP with reduction potentials measured potentiometrically using a Pt electrode (EPt) showed that ECRP was 100-150 mV more negative than EPt. When EPt was measured with small additions of CRPs, the systematic difference between EPt and ECRP was eliminated, suggesting that these CRPs are effective mediators of electron transfer between mineral and electrode surfaces. Model contaminants (4-chloronitrobenzene, 2-chloroacetophenone, and carbon tetrachloride) were used as kinetic CRPs. The reduction rate constants of kinetic CRPs correlated well with the ECRP for mineral suspensions. Using the rate constants compiled from literature for contaminants and relative mineral reduction potentials based on ECRP measurements, qualitatively consistent trends were obtained, suggesting that CRP-based assays may be useful for estimating abiotic NA rates of contaminants in groundwater.


Asunto(s)
Tetracloruro de Carbono/química , Monitoreo del Ambiente/métodos , Compuestos Ferrosos/química , Nitrobencenos/química , Contaminantes Químicos del Agua/química , omegacloroacetofenona/química , Hierro/química , Minerales/química , Oxidación-Reducción , Potenciometría , Espectrofotometría Ultravioleta
6.
Molecules ; 20(6): 9906-14, 2015 May 28.
Artículo en Inglés | MEDLINE | ID: mdl-26029859

RESUMEN

A polymer-supported terpyridine palladium complex was prepared. The complex was found to promote hydrodechlorination of aryl chlorides with potassium formate in seawater. Generally, reductive cleavage of aryl chlorides using transition metal catalysts is more difficult than that of aryl bromides and iodides (reactivity: I > Br > Cl); however, the results obtained did not follow the general trend. Therefore, we investigated the reaction inhibition agents and found a method to remove these inhibitors. The polymeric catalysts showed high catalytic activity and high reusability for transfer reduction in seawater.


Asunto(s)
Acetofenonas/química , Halógenos/aislamiento & purificación , Paladio/química , Piridinas/química , Contaminantes Químicos del Agua/química , omegacloroacetofenona/análogos & derivados , Catálisis , Equipo Reutilizado , Oxidación-Reducción , Agua de Mar/química , Purificación del Agua/métodos , omegacloroacetofenona/química
7.
J R Army Med Corps ; 161(2): 94-9, 2015 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24379300

RESUMEN

INTRODUCTION: 2-Chloroacetophenone (CN), o-chlorobenzylidene malonitrile (CS) and oleoresin capsicum (OC) are common riot control agents. While serious systemic effects are uncommon, exposure to high concentrations may lead to severe complications and even death. The aim of this narrative review is to summarise all main aspects of the riot control agents CN, CS and OC toxicology, including mechanisms of toxicity, clinical features and management. METHODS: OVID MEDLINE and ISI Web of Science were searched for terms associated with CN, CS and OC toxicity in humans and those describing the mechanism of action, clinical features and treatment protocols. RESULTS: CN, CS and OC are effective lacrimating agents; evidence for toxicity, as measured by the threshold for irritation, is greatest for CN, followed by CS and OC. Typically, ocular and respiratory tract irritation occurs within 20-60 s of exposure. Ocular effects involve blepharospasm, photophobia, conjunctivitis and periorbital oedema. Following inhalation, effects may include a stinging or burning sensation in the nose, tight chest, sore throat, coughing, dyspnoea and difficulty breathing. Dermal outcomes are variable, more severe for CN and include dermal irritation, bulla formation and subcutaneous oedema. Removal from the contaminated area and fresh air is a priority. There is no antidote; treatment consists of thorough decontamination and symptom-directed supportive care. Ocular exposure requires thorough eye decontamination, an eye exam and appropriate pain management. Monitoring and support of respiratory function is important in patients with significant respiratory symptoms. Standard treatment protocols may be required with patients with pre-existing respiratory conditions. Dermal exposures may require systemic steroids for patients who develop delayed contact dermatitis. CONCLUSIONS: CN, CS and OC are effective riot control agents. In the majority of exposures, significant clinical effects are not anticipated. The irritant effects can be minimised both by rapid evacuation from sites of exposure, decontamination and appropriate supportive care.


Asunto(s)
Extractos Vegetales , Sustancias para Control de Disturbios Civiles , o-Clorobencilidenomalonitrila , omegacloroacetofenona , Humanos , Medicina Militar , Personal Militar , Equipos de Seguridad , Tumultos/prevención & control
8.
Forensic Sci Med Pathol ; 10(2): 223-8, 2014 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-24526411

RESUMEN

The excited delirium syndrome (EDS) is a life-threatening condition caused by a variety of factors including drug intoxication and psychiatric illness. Fatal instances of excited delirium frequently come to the attention of the medical examiner/coroner due to the circumstances and potential causes. Excited delirium may include paranoid, aggressive, and incoherent behavior which may lead to an encounter with law enforcement. In some instances, the person may die while in the presence of law enforcement. This circumstance further broadens the potential causes of death particularly as EDS has no pathognomonic autopsy finding. Although the syndrome of excited delirium is sufficient to explain death, other intervening causes need to be considered. These include chest or neck compression during restraint, blunt trauma, and underlying natural disease. Since chest/neck compression, natural disease (e.g., atherosclerosis), blunt trauma, and excited delirium are not mutually exclusive, all may be present in one death. The forensic pathologist's role is to determine what caused and/or contributed to the death. When attempting to determine the proximate cause of death in instances with multiple potential causes, determining the mechanism of death often is useful. As not all causes of death have pathologically-demonstrable mechanisms of death, examination of the circumstances of the death often are diagnostically important. The main goal of the autopsy of deaths suspected to be due to EDS is to identify (or exclude) intervening diseases or injuries sufficient to explain the death in the context of the investigated circumstances.


Asunto(s)
Delirio/fisiopatología , Medicina Legal , Agitación Psicomotora/fisiopatología , Asfixia/diagnóstico , Asfixia/etiología , Autopsia , Lesiones por Armas Conductoras de Energía/fisiopatología , Diagnóstico Diferencial , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos , Humanos , Irritantes/efectos adversos , Esfuerzo Físico/fisiología , Rol Profesional , Trastornos Psicóticos/fisiopatología , Restricción Física/efectos adversos , Restricción Física/fisiología , Estrés Fisiológico/fisiología , Trastornos Relacionados con Sustancias/fisiopatología , Síndrome , Heridas y Lesiones/patología , omegacloroacetofenona/efectos adversos
9.
Biotechnol Bioeng ; 110(8): 2311-5, 2013 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-23475609

RESUMEN

Escherichia coli cells co-expressing genes coding for Candida tenuis xylose reductase and Candida boidinii formate dehydrogenase were used for the bioreduction of o-chloroacetophenone with in situ coenzyme recycling. The product, (S)-1-(2-chlorophenyl)ethanol, is a key chiral intermediate in the synthesis of polo-like kinase 1 inhibitors, a new class of chemotherapeutic drugs. Production of the alcohol in multi-gram scale requires intensification and scale-up of the biocatalyst production, biotransformation, and downstream processing. Cell cultivation in a 6.9-L bioreactor led to a more than tenfold increase in cell concentration compared to shaken flask cultivation. The resultant cells were used in conversions of 300 mM substrate to (S)-1-(2-chlorophenyl)ethanol (e.e. >99.9%) in high yield (96%). Results obtained in a reaction volume of 500 mL were identical to biotransformations carried out in 1 mL (analytical) and 15 mL (preparative) scale. Optimization of product isolation based on hexane extraction yielded 86% isolated product. Biotransformation and extraction were accomplished in a stirred tank reactor equipped with pH and temperature control. The developed process lowered production costs by 80% and enabled (S)-1-(2-chlorophenyl)ethanol production within previously defined economic boundaries. A simple and efficient way to synthesize (S)-1-(2-chlorophenyl)ethanol in an isolated amount of 20 g product per reaction batch was demonstrated.


Asunto(s)
Alcoholes/metabolismo , Aldehído Reductasa/metabolismo , Escherichia coli/metabolismo , Formiato Deshidrogenasas/metabolismo , Ingeniería Metabólica/métodos , omegacloroacetofenona/metabolismo , Aldehído Reductasa/genética , Biotecnología/métodos , Biotransformación , Candida/enzimología , Candida/genética , Escherichia coli/enzimología , Escherichia coli/genética , Formiato Deshidrogenasas/genética , Oxidación-Reducción , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo
12.
Microb Cell Fact ; 11: 119, 2012 Sep 04.
Artículo en Inglés | MEDLINE | ID: mdl-22947394

RESUMEN

BACKGROUND: The bacterium Acetobacter sp. CCTCC M209061 is a promising whole-cell biocatalyst with exclusive anti-Prelog stereoselectivity for the reduction of prochiral ketones that can be used to make valuable chiral alcohols such as (R)-4-(trimethylsilyl)-3-butyn-2-ol. Although it has promising catalytic properties, its stability and reusability are relatively poor compared to other biocatalysts. Hence, we explored various materials for immobilizing the active cells, in order to improve the operational stability of biocatalyst. RESULTS: It was found that Ca-alginate give the best immobilized biocatalyst, which was then coated with chitosan to further improve its mechanical strength and swelling-resistance properties. Conditions were optimized for formation of reusable immobilized beads which can be used for repeated batch asymmetric reduction of 4'-chloroacetophenone. The optimized immobilized biocatalyst was very promising, with a specific activity of 85% that of the free-cell biocatalyst (34.66 µmol/min/g dw of cells for immobilized catalyst vs 40.54 µmol/min/g for free cells in the asymmetric reduction of 4'-chloroacetophenone). The immobilized cells showed better thermal stability, pH stability, solvent tolerance and storability compared with free cells. After 25 cycles reaction, the immobilized beads still retained >50% catalytic activity, which was 3.5 times higher than degree of retention of activity by free cells reused in a similar way. The cells could be recultured in the beads to regain full activity and perform a further 25 cycles of the reduction reaction. The external mass transfer resistances were negligible as deduced from Damkohler modulus Da < <1, and internal mass transfer restriction affected the reduction action but was not the principal rate-controlling step according to effectiveness factors η < 1 and Thiele modulus 0.3<∅ <1. CONCLUSIONS: Ca-alginate coated with chitosan is a highly effective material for immobilization of Acetobacter sp. CCTCC M209061 cells for repeated use in the asymmetric reduction of ketones. Only a small cost in terms of the slightly lower catalytic activity compared to free cells could give highly practicable immobilized biocatalyst.


Asunto(s)
Acetobacter/metabolismo , Cetonas/metabolismo , Alginatos/química , Alquinos/química , Alquinos/metabolismo , Biocatálisis , Butanoles/química , Butanoles/metabolismo , Células Inmovilizadas/metabolismo , Quitosano/química , Ácido Glucurónico/química , Ácidos Hexurónicos/química , Concentración de Iones de Hidrógeno , Cetonas/química , Oxidación-Reducción , Solventes/química , Estereoisomerismo , Temperatura , omegacloroacetofenona/química , omegacloroacetofenona/metabolismo
13.
Microb Cell Fact ; 11: 7, 2012 Jan 11.
Artículo en Inglés | MEDLINE | ID: mdl-22236335

RESUMEN

BACKGROUND: Enzymatic NADH or NADPH-dependent reduction is a widely applied approach for the synthesis of optically active organic compounds. The overall biocatalytic conversion usually involves in situ regeneration of the expensive NAD(P)H. Oxidation of formate to carbon dioxide, catalyzed by formate dehydrogenase (EC 1.2.1.2; FDH), presents an almost ideal process solution for coenzyme regeneration that has been well established for NADH. Because isolated FDH is relatively unstable under a range of process conditions, whole cells often constitute the preferred form of the biocatalyst, combining the advantage of enzyme protection in the cellular environment with ease of enzyme production. However, the most prominent FDH used in biotransformations, the enzyme from the yeast Candida boidinii, is usually expressed in limiting amounts of activity in the prime host for whole cell biocatalysis, Escherichia coli. We therefore performed expression engineering with the aim of enhancing FDH activity in an E. coli ketoreductase catalyst. The benefit resulting from improved NADH regeneration capacity is demonstrated in two transformations of technological relevance: xylose conversion into xylitol, and synthesis of (S)-1-(2-chlorophenyl)ethanol from o-chloroacetophenone. RESULTS: As compared to individual expression of C. boidinii FDH in E. coli BL21 (DE3) that gave an intracellular enzyme activity of 400 units/g(CDW), co-expression of the FDH with the ketoreductase (Candida tenuis xylose reductase; XR) resulted in a substantial decline in FDH activity. The remaining FDH activity of only 85 U/g(CDW) was strongly limiting the overall catalytic activity of the whole cell system. Combined effects from increase in FDH gene copy number, supply of rare tRNAs in a Rosetta strain of E. coli, dampened expression of the ketoreductase, and induction at low temperature (18°C) brought up the FDH activity threefold to a level of 250 U/g(CDW) while reducing the XR activity by just 19% (1140 U/g(CDW)). The E. coli whole-cell catalyst optimized for intracellular FDH activity showed improved performance in the synthesis of (S)-1-(2-chlorophenyl)ethanol, reflected in a substantial, up to 5-fold enhancement of productivity (0.37 g/g(CDW)) and yield (95% based on 100 mM ketone used) as compared to the reference catalyst. For xylitol production, the benefit of enhanced FDH expression was observed on productivity only after elimination of the mass transfer resistance caused by the cell membrane. CONCLUSIONS: Expression engineering of C. boidinii FDH is an important strategy to optimize E. coli whole-cell reductase catalysts that employ intracellular formate oxidation for regeneration of NADH. Increased FDH-activity was reflected by higher reduction yields of D-xylose and o-chloroacetophenone conversions provided that mass transfer limitations were overcome.


Asunto(s)
Aldehído Reductasa/biosíntesis , Escherichia coli/enzimología , Formiato Deshidrogenasas/biosíntesis , NAD/metabolismo , Aldehído Reductasa/genética , Biocatálisis , Candida/enzimología , Escherichia coli/genética , Escherichia coli/metabolismo , Formiato Deshidrogenasas/genética , Ingeniería de Proteínas , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/genética , omegacloroacetofenona/metabolismo
14.
J Org Chem ; 77(20): 9094-101, 2012 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-22963457

RESUMEN

The nonaccessibility of phenyl cations by irradiation of electron-poor aryl chlorides was circumvented by transforming the carbonyl group of aromatic ketones or aldehydes into the corresponding 1,3-dioxolanes and the carboxyl group of benzoate ester into an orthoester functionality. This transformation allowed the heterolytic photoactivation of the Ar-Cl bond in protic media and the generation of phenyl cations. In the presence of π-bond nucleophiles, arylated products were obtained in good to excellent yields.


Asunto(s)
Acetales/síntesis química , Argón/química , Benzaldehídos/química , Cloruros/química , omegacloroacetofenona/química , Acetales/química , Estructura Molecular , Procesos Fotoquímicos , Teoría Cuántica
16.
Biotechnol Bioeng ; 108(4): 797-803, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21404254

RESUMEN

Chiral 1-(o-chlorophenyl)-ethanols are key intermediates in the synthesis of chemotherapeutic substances. Enantioselective reduction of o-chloroacetophenone is a preferred method of production but well investigated chemo- and biocatalysts for this transformation are currently lacking. Based on the discovery that Candida tenuis xylose reductase converts o-chloroacetophenone with useful specificity (kcat/Km=340 M(-1) s(-1)) and perfect S-stereoselectivity, we developed whole-cell catalysts from Escherichia coli and Saccharomyces cerevisiae co-expressing recombinant reductase and a suitable system for recycling of NADH. E. coli surpassed S. cerevisiae sixfold concerning catalytic productivity (3 mmol/g dry cells/h) and total turnover number (1.5 mmol substrate/g dry cells). o-Chloroacetophenone was unexpectedly "toxic," and catalyst half-life times of only 20 min (E. coli) and 30 min (S. cerevisiae) in the presence of 100 mM substrate restricted the time of batch processing to maximally ∼5 h. Systematic reaction optimization was used to enhance the product yield (≤60%) of E. coli catalyzed conversion of 100 mM o-chloroacetophenone which was clearly limited by catalyst instability. Supplementation of external NAD+ (0.5 mM) to cells permeabilized with polymyxin B sulfate (0.14 mM) resulted in complete conversion providing 98 mM S-1-(o-chlorophenyl)-ethanol. The strategies considered for optimization of reduction rate should be generally useful, however, especially under process conditions that promote fast loss of catalyst activity.


Asunto(s)
Aldehído Reductasa/metabolismo , Escherichia coli/enzimología , Microbiología Industrial/métodos , Saccharomyces cerevisiae/enzimología , omegacloroacetofenona/metabolismo , Aldehído Reductasa/genética , Biotransformación , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo
17.
J Biotechnol ; 325: 57-64, 2021 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-33220340

RESUMEN

The asymmetric reduction of ketones is a frequently used synthesis route towards chiral alcohols. Amongst available chemo- and biocatalysts the latter stand out in terms of product enantiopurity. Their application is, however, restricted by low reaction output, often rooted in limited enzyme stability under operational conditions. Here, addition of 2-hydroxypropyl-ß-cyclodextrin to bioreductions of o-chloroacetophenone enabled product concentrations of up to 29 % w/v at full conversion and 99.97 % e.e. The catalyst was an E. coli strain co-expressing NADH-dependent Candida tenuis xylose reductase and a yeast formate dehydrogenase for coenzyme recycling. Analysis of the lyophilized biocatalyst showed that E. coli cells were leaky with catalytic activity found as free-floating enzymes and associated with the biomass. The biocatalyst was stabilized and activated in the reaction mixture by 2-hydroxypropyl-ß-cyclodextrin. Substitution of the wild-type xylose reductase by a D51A mutant further improved bioreductions. In previous optimization strategies, hexane was added as second phase to protect the labile catalyst from adverse effects of hydrophobic substrate and product. The addition of 2-hydroxypropyl-ß-cyclodextrin (11 % w/v) instead of hexane (20 % v/v) increased the yield on biocatalyst 6.3-fold. A literature survey suggests that bioreduction enhancement by addition of cyclodextrins is not restricted to specific enzyme classes, catalyst forms or substrates.


Asunto(s)
Ciclodextrinas , omegacloroacetofenona , Escherichia coli/genética , Formiato Deshidrogenasas , Saccharomycetales
18.
Eur J Med Chem ; 214: 113225, 2021 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-33550182

RESUMEN

Pyruvate dehydrogenase kinases (PDKs) are promising therapeutic targets that have received increasing attentions in cancer metabolism. In this paper, we report the synthesis and biological evaluation of a series of novel dichloroacetophenones as potent PDKs inhibitors. Structure-activity relationship analysis enabled us to identify a potent compound 6u, which inhibited PDKs with an EC50 value of 0.09 µM, and reduced various cancer cells proliferation with IC50 values ranging from 1.1 to 3.8 µM, while show weak effect against non-cancerous L02 cell (IC50 > 10 µM). In the A375 xenograft model, 6u displayed an obvious antitumor activity at a dose of 5 mg/kg, but with no negative effect to the mice weight. Molecular docking suggested that 6u formed direct hydrogen bond interactions with Ser75 and Gln61 in PDK1, and meanwhile the aniline skeleton in 6u was sandwiched by the conserved hydrophobic residues Phe78 and Phe65, which contribute to the biochemical activity improvement. Moreover, 6u induced A375 cell apoptosis and cell arrest in G1 phase, and inhibited cancer cell migration. In addition, 6u altered glucose metabolic pathway in A375 cell by decreasing lactate formation and increasing ROS production and OCR consumption, which could serve as a potential modulator to reprogram the glycolysis pathway in cancer cell.


Asunto(s)
Antineoplásicos/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Piruvato Deshidrogenasa Quinasa Acetil-Transferidora/antagonistas & inhibidores , omegacloroacetofenona/farmacología , Antineoplásicos/síntesis química , Antineoplásicos/química , Apoptosis/efectos de los fármacos , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Humanos , Estructura Molecular , Inhibidores de Proteínas Quinasas/síntesis química , Inhibidores de Proteínas Quinasas/química , Piruvato Deshidrogenasa Quinasa Acetil-Transferidora/metabolismo , Relación Estructura-Actividad , Células Tumorales Cultivadas , omegacloroacetofenona/síntesis química , omegacloroacetofenona/química
19.
Oxid Med Cell Longev ; 2021: 6660193, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33777318

RESUMEN

Palmatine (PAL), a natural isoquinoline alkaloid, possesses extensive biological and pharmaceutical activities, including antioxidative stress, anti-inflammatory, antitumor, neuroprotective, and gastroprotective activities. However, it is unknown whether PAL has a protective effect against ischemic stroke and cerebral ischemia/reperfusion (I/R) injury. In the present study, a transient middle cerebral artery occlusion (MCAO) mouse model was used to mimic ischemic stroke and cerebral I/R injury in mice. Our study demonstrated that PAL treatment ameliorated cerebral I/R injury by decreasing infarct volume, neurological scores, and brain water content. PAL administration attenuated oxidative stress, the inflammatory response, and neuronal apoptosis in mice after cerebral I/R injury. In addition, PAL treatment also decreases hypoxia and reperfusion- (H/R-) induced neuronal injury by reducing oxidative stress, the inflammatory response, and neuronal apoptosis. Moreover, the neuroprotective effects of PAL were associated with the activation of the AMP-activated protein kinase (AMPK)/nuclear factor E2-related factor 2 (Nrf2) pathway, and Nrf2 knockdown offsets PAL-mediated antioxidative stress and anti-inflammatory effects. Therefore, our results suggest that PAL may be a novel treatment strategy for ischemic stroke and cerebral I/R injury.


Asunto(s)
Proteínas Quinasas Activadas por AMP/metabolismo , Trastornos Cerebrovasculares , Factor 2 Relacionado con NF-E2/metabolismo , Palmitatos/farmacología , Daño por Reperfusión , Transducción de Señal/efectos de los fármacos , Trastornos Cerebrovasculares/metabolismo , Trastornos Cerebrovasculares/patología , Trastornos Cerebrovasculares/prevención & control , Daño por Reperfusión/metabolismo , Daño por Reperfusión/patología , Daño por Reperfusión/prevención & control , omegacloroacetofenona
20.
Int J Mol Med ; 47(3)2021 03.
Artículo en Inglés | MEDLINE | ID: mdl-33448314

RESUMEN

Mesenchymal stem cells (MSCs) have the function of repairing damaged tissue, which is known to be mediated by the secretome, the collection of secretory materials shed from MSCs. Adjusting the culture conditions of MSCs can lead to a significant difference in the composition of the secretome. It was hypothesized that pre­sensitization of MSCs with specific disease­causing agents could harness MSCs to release the therapeutic materials specialized for the disease. To validate this hypothesis, the present study aimed to generate a 'disease­specific secretome' for hepatitis caused by hepatitis B virus using hepatitis BX antigen (HBx) as a disease­causing material. Secretary materials (HBx­IS) were collected following the stimulation of adipose­derived stem cells (ASCs) with 100­fold diluted culture media of AML12 hepatocytes that had been transfected with pcDNA­HBx for 24 h. An animal model of hepatitis B was generated by injecting HBx into mice, and the mice were subsequently intravenously administered a control secretome (CS) or HBx­IS. Compared with the CS injection, the HBx­IS injection significantly reduced the serum levels of interleukin­6 and tumor necrosis factor­α (pro­inflammatory cytokines). Western blot analysis and immunohistochemistry of the liver specimens revealed that the HBx­IS injection led to a higher expression of liver regeneration­related markers, including hepatocyte growth factor and proliferating cell nuclear antigen, a lower expression of pro­apoptotic markers, such as cleaved caspase 3 and Bim in mouse livers, and a lower expression of pro­inflammatory markers (F4/80 and CD68) compared to the CS injection. HBx­IS exhibited higher liver regenerative, anti­inflammatory and anti­apoptotic properties, particularly in the mouse model of hepatitis B compared to CS. This suggests that the secretome obtained by stimulating ASCs with disease­causing agents may have a more prominent therapeutic effect on the specific disease than the naïve secretome.


Asunto(s)
Tejido Adiposo/metabolismo , Virus de la Hepatitis B/metabolismo , Hepatitis B , Células Madre Mesenquimatosas/metabolismo , Tejido Adiposo/patología , Animales , Medios de Cultivo Condicionados/farmacología , Modelos Animales de Enfermedad , Hepatitis B/tratamiento farmacológico , Hepatitis B/metabolismo , Hepatitis B/patología , Hepatocitos/metabolismo , Hepatocitos/patología , Humanos , Masculino , Células Madre Mesenquimatosas/patología , Ratones Endogámicos BALB C , Transactivadores/metabolismo , Proteínas Reguladoras y Accesorias Virales/metabolismo , omegacloroacetofenona
SELECCIÓN DE REFERENCIAS
Detalles de la búsqueda