Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 23
Filtrar
1.
Phys Rev Lett ; 130(20): 200404, 2023 May 19.
Artículo en Inglés | MEDLINE | ID: mdl-37267563

RESUMEN

We measure superfluid transport of strongly interacting fermionic lithium atoms through a quantum point contact with local, spin-dependent particle loss. We observe that the characteristic non-Ohmic superfluid transport enabled by high-order multiple Andreev reflections transitions into an excess Ohmic current as the dissipation strength exceeds the superfluid gap. We develop a model with mean-field reservoirs connected via tunneling to a dissipative site. Our calculations in the Keldysh formalism reproduce the observed nonequilibrium particle current, yet do not fully explain the observed loss rate or spin current.

2.
Curr Mol Pharmacol ; 16(5): 530-541, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-36263474

RESUMEN

Breast cancer (BC) is accountable for a large number of female-related malignancies that lead to lethality worldwide. Various factors are considered in the occurrence of BC, including the deregulation of cancer stem cells (CSCs) and epithelial-mesenchymal transition (EMT). Genetic factors such as microRNAs (miRs) are crucially responsible for BC progression and aggressiveness. Hence, the association of miRs and EMT regulators (e.g., Wnt signaling pathway) is of importance. In the present review, we accurately discussed this interplay (interaction between Wnt and miRs) concerning cell - invasion, -migration, -differentiation, -chemoresistance, survival, and-proliferation, and BC prognosis. The putative therapeutic agents, multidrug resistance (MDR) evade, and possible molecular targets are described as well.


Asunto(s)
Neoplasias de la Mama , MicroARNs , Humanos , Femenino , MicroARNs/genética , MicroARNs/metabolismo , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Neoplasias de la Mama/patología , Vía de Señalización Wnt/genética , Pronóstico , Transición Epitelial-Mesenquimal/genética , Regulación Neoplásica de la Expresión Génica , Movimiento Celular , Línea Celular Tumoral , Proliferación Celular/genética
3.
Artículo en Inglés | MEDLINE | ID: mdl-35786197

RESUMEN

Obesity and dyslipidemia are common disorders universally. According to the acquired outcomes of recent studies, dietary supplementations which have great content of phenolic compounds exert protective effects against obesity and dyslipidemia. Grape [Vitis vinifera] seeds are considered attractive sources of phenolic compounds with anti-oxidative stress and anti-inflammatory effects. There are also various experimental studies describing hepatoprotective, neuroprotective, anti-aging, cardioprotective, and anti-carcinogenic effects of polyphenols isolated from grape seed, highlighting the therapeutic and biological aspects of proanthocyanidins. The present review article first discusses pharmacological, botanical, toxicological, and phytochemical characteristics of Vitis vinifera seeds and afterward designates the protective properties which are attributed to the intake of grape seeds in obesity and hyperlipidemia. Overall valuable and updated findings of this study display that polyphenol of grape seeds has meaningful impacts on the regulation of lipid profile levels and management of obesity.


Asunto(s)
Antioxidantes , Vitis , Antioxidantes/farmacología , Antioxidantes/uso terapéutico , Antioxidantes/análisis , Vitis/química , Polifenoles/farmacología , Polifenoles/uso terapéutico , Fenoles , Semillas/química , Obesidad/tratamiento farmacológico , Lípidos/análisis
4.
Behav Brain Funct ; 18(1): 3, 2022 Jan 29.
Artículo en Inglés | MEDLINE | ID: mdl-35093121

RESUMEN

Regarding the epidemiological studies, neurological dysfunctions caused by cerebral ischemia or neurodegenerative diseases (NDDs) have been considered a pointed matter. Mount-up shreds of evidence support that both autophagy and reactive oxygen species (ROS) are involved in the commencement and progression of neurological diseases. Remarkably, oxidative stress prompted by an increase of ROS threatens cerebral integrity and improves the severity of other pathogenic agents such as mitochondrial damage in neuronal disturbances. Autophagy is anticipated as a cellular defending mode to combat cytotoxic substances and damage. The recent document proposes that the interrelation of autophagy and ROS creates a crucial function in controlling neuronal homeostasis. This review aims to overview the cross-talk among autophagy and oxidative stress and its molecular mechanisms in various neurological diseases to prepare new perceptions into a new treatment for neurological disorders. Furthermore, natural/synthetic agents entailed in modulation/regulation of this ambitious cross-talk are described.


Asunto(s)
Enfermedades Neurodegenerativas , Estrés Oxidativo , Autofagia , Homeostasis , Humanos , Especies Reactivas de Oxígeno
5.
Curr Drug Targets ; 23(5): 458-470, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34636295

RESUMEN

Cardiometabolic diseases (CMD) have caused a great burden in terms of morbidity and mortality worldwide. The vicious cycle of CMD consists of type II diabetes, hypertension, dyslipidemia, obesity, and atherosclerosis. They have interlinked pathways, interacting and interconnecting with each other. The natural flavonoid chrysin has been shown to possess a broad spectrum of therapeutic activities for human health. Herein, we did an in-depth investigation of the novel mechanisms of chrysin's cardioprotection against cardiometabolic disorders. Studies have shown that chrysin protects the cardiovascular system by enhancing the intrinsic antioxidative defense system. This antioxidant property enhanced by chrysin protects against several risk factors of cardiometabolic disorders, including atherosclerosis, vascular inflammation and dysfunction, platelet aggregation, hypertension, dyslipidemia, cardiotoxicity, myocardial infarction, injury, and remodeling, diabetes-induced injuries, and obesity. Chrysin also exhibited anti-inflammatory mechanisms through inhibiting pro-inflammatory pathways, including NF-κB, MAPK, and PI3k/Akt. Furthermore, chrysin modulated NO, RAS, AGE/RAGE, and PPARs pathways which contributed to the risk factors of cardiometabolic disorders. Taken together, the mechanisms in which chrysin protects against cardiometabolic disorder are more than merely antioxidation and anti-inflammation in the cardiovascular system.


Asunto(s)
Aterosclerosis , Diabetes Mellitus Tipo 2 , Hipertensión , Antiinflamatorios/farmacología , Antiinflamatorios/uso terapéutico , Antioxidantes/farmacología , Antioxidantes/uso terapéutico , Aterosclerosis/tratamiento farmacológico , Cardiotoxicidad/tratamiento farmacológico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Flavonoides/farmacología , Flavonoides/uso terapéutico , Humanos , Hipertensión/tratamiento farmacológico , Obesidad/tratamiento farmacológico , Fosfatidilinositol 3-Quinasas
6.
Curr Pharm Biotechnol ; 23(5): 634-644, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-34250871

RESUMEN

Alzheimer's disease (AD) is a brain-linked pathophysiological condition with neuronal degeneration and cognition dysfunctions and other debilitations. Due to the growing prevalence of AD, there is a highly commended trend to accelerate and develop analytical technologies for easy, costeffective, and sensitive detection of AD biomarkers. Biosensors are commanding analytical devices that can conduct biological responses on transducers into measurable signals. This review focuses on up-todate developmets, contests, and tendencies regarding AD biosensing principally, with the emphasis on the exclusive possessions of nanomaterials. In the last decade, remarkable advancements have been achieved to the progression of biosensors, predominantly optical and electrochemical, for the detection of AD biomarkers. These analytical devices can assist the case finding and management of AD.


Asunto(s)
Enfermedad de Alzheimer , Técnicas Biosensibles , Disfunción Cognitiva , Nanoestructuras , Enfermedad de Alzheimer/diagnóstico , Péptidos beta-Amiloides , Biomarcadores , Humanos , Proteínas tau
7.
Biomed Pharmacother ; 141: 111906, 2021 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-34328092

RESUMEN

Neurological diseases are responsible for a large number of morbidities and mortalities in the world. Flavonoids are phytochemicals that possess various health-promoting impacts. Chrysin, a natural flavonoid isolated from diverse fruits, vegetables, and even mushrooms, has several pharmacological activities comprising antioxidant, anti-inflammatory, antiapoptotic, anticancer, and neuroprotective effects. The current study was designed to review the relationship between chrysin administration and neurological complications by discussing the feasible mechanism and signaling pathways. Herein, we mentioned the sources, pharmacological properties, chemistry, and drug delivery systems associated with chrysin pharmacotherapy. The role of chrysin was discussed in depression, anxiety, neuroinflammation, Alzheimer's disease, Parkinson's disease, Huntington's disease, epilepsy, cerebral ischemia, spinal cord injury, neuropathy, Multiple Sclerosis, and Guillain-Barré Syndrome. The findings indicate that chrysin has protective effects against neurological conditions by modulating oxidative stress, inflammation, and apoptosis in animal models. However, more studies should be done to clear the neuroprotective effects of chrysin.


Asunto(s)
Flavonoides/química , Flavonoides/uso terapéutico , Enfermedades del Sistema Nervioso/tratamiento farmacológico , Animales , Encéfalo/efectos de los fármacos , Encéfalo/metabolismo , Sistemas de Liberación de Medicamentos , Flavonoides/administración & dosificación , Humanos , Transducción de Señal/efectos de los fármacos
8.
Expert Rev Neurother ; 21(6): 625-642, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-33910446

RESUMEN

Introduction: Alzheimer's disease (AD) is a progressive neurodegenerative disease accompanying memory deficits. The available pharmaceutical care has some limitations mostly entailing side effects, shelf-life, and patient's compliance. The momentous implications of nutraceuticals in AD have attracted scientists. Several preclinical studies for the investigation of nutraceuticals have been conducted.Areas covered: This review focuses on the potential use of a nutraceuticals-based therapeutic approach to treat and prevent AD. Increasing knowledge of AD pathogenesis has led to the discovery of new therapeutic targets including pathophysiological mechanisms and various cascades. Hence, the present contribution will attend to the most popular and effective nutraceuticals with proposed brief mechanisms entailing antioxidant, anti-inflammatory, autophagy regulation, mitochondrial homeostasis, and more. Therefore, even though the effectiveness of nutraceuticals cannot be dismissed, it is essential to do further high-quality randomized clinical trials.Expert opinion: According to the potential of nutraceuticals to combat AD as multi-target directed drugs, there is critical importance to assess them as feasible lead compounds for drug discovery and development. To the best of the authors' knowledge, modification of blood-brain barrier permeability, bioavailability, and features of randomized clinical trials should be considered in prospective studies.


Asunto(s)
Enfermedad de Alzheimer , Enfermedades Neurodegenerativas , Enfermedad de Alzheimer/terapia , Barrera Hematoencefálica , Suplementos Dietéticos , Humanos , Estudios Prospectivos
9.
Cancer Cell Int ; 21(1): 214, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33858433

RESUMEN

Chrysin has been shown to exert several beneficial pharmacological activities. Chrysin has anti-cancer, anti-viral, anti-diabetic, neuroprotective, cardioprotective, hepatoprotective, and renoprotective as well as gastrointestinal, respiratory, reproductive, ocular, and skin protective effects through modulating signaling pathway involved in apoptosis, oxidative stress, and inflammation. In the current review, we discussed the emerging cellular and molecular mechanisms underlying therapeutic indications of chrysin in various cancers. Online databases comprising Scopus, PubMed, Embase, ProQuest, Science Direct, Web of Science, and the search engine Google Scholar were searched for available and eligible research articles. The search was conducted by using MeSH terms and keywords in title, abstract, and keywords. In conclusion, experimental studies indicated that chrysin could ameliorate cancers of the breast, gastrointestinal tract, liver and hepatocytes, bladder, male and female reproductive systems, choroid, respiratory tract, thyroid, skin, eye, brain, blood cells, leukemia, osteoblast, and lymph. However, more studies are needed to enhance the bioavailability of chrysin and evaluate this agent in clinical trial studies.

10.
Transl Oncol ; 14(6): 101070, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33789222

RESUMEN

Cell-based immunotherapies have been selected for the front-line cancer treatment approaches. Among them, CAR-T cells have shown extraordinary effects in hematologic diseases including chemotherapy-resistant acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL), and non-Hodgkin lymphoma (NHL). In this approach, autologous T cells isolated from the patient's body genetically engineered to express a tumor specific synthetic receptor against a tumor antigen, then these cells expanded ex vivo and re-infusion back to the patient body. Recently, significant clinical response and high rates of complete remission of CAR T cell therapy in B-cell malignancies led to the approval of Kymriah and Yescarta (CD19-directed CAR-T cells) were by FDA for treatment of acute lymphoblastic leukemia and diffuse large B-cell lymphoma. Despite promising therapeutic outcomes, CAR T cells also can elicit the immune-pathologic effects, such as Cytokine Release Syndrome (CRS), Tumor Lysis Syndrome (TLS), and on-target off-tumor toxicity, that hampered its application. Ineffective control of these highly potent synthetic cells causes discussed potentially life-threatening toxicities, so researchers have developed several mechanisms to remote control CAR T cells. In this paper, we briefly review the introduced toxicities of CAR-T cells, then describe currently existing control approaches and review their procedure, pros, and cons.

11.
Phytother Res ; 35(6): 3078-3112, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33569875

RESUMEN

Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a transcriptional signaling pathway that plays a crucial role in numerous clinical complications. Pivotal roles of Nrf2 have been proved in cancer, autoimmune diseases, neurodegeneration, cardiovascular diseases, diabetes mellitus, renal injuries, respiratory conditions, gastrointestinal disturbances, and general disorders related to oxidative stress, inflammation, apoptosis, gelatinolysis, autophagy, and fibrogenesis processes. Green tea catechins as a rich source of phenolic compounds can deal with various clinical problems and manifestations. In this review, we attempted to focus on intervention between green tea catechins and Nrf2. Green tea catechins especially epigallocatechin gallate (EGCG) elucidated the protective role of Nrf2 and its downstream molecules in various disorders through Keap-1, HO-1, NQO-1, GPx, GCLc, GCLm, NF-kB cross-link, kinases, and apoptotic proteins. Subsequently, we compiled an updated expansions of the Nrf2 role as a gate to manage and protect different disorders and feasible indications of green tea catechins through this signaling pathway. The present review highlighted recent evidence-based data in silico, in vitro, and in vivo studies on an outline for future clinical trials.


Asunto(s)
Catequina/análogos & derivados , Factor 2 Relacionado con NF-E2/metabolismo , Té/química , Animales , Apoptosis/efectos de los fármacos , Catequina/farmacología , Humanos , Inflamación/tratamiento farmacológico , FN-kappa B/metabolismo , Estrés Oxidativo/efectos de los fármacos , Transducción de Señal/efectos de los fármacos
12.
Int J Biol Macromol ; 172: 93-103, 2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33440210

RESUMEN

Neurodegenerative diseases are incongruous, commonly age-related disorders characterized by progressive neuronal loss, comprising the most prevalent being Alzheimer's disease, Parkinson's disease, and Huntington's disease. Perilous health states are anticipated following the neurodegeneration. Their etiology remains largely ambiguous, while various mechanisms are ascribed to their pathogenesis. A recommended conception is regarding the role of p53, as a transcription factor regulating numerous cellular pathways comprising apoptosis. Neuronal fates are a feasible occurrence that contributes to all neurodegenerative diseases. In this work, we review the research investigated the potential role of p53 in the pathogenesis of these diseases. We put special emphasis on intricate We not only describe aberrant changes in p53 level/activity observed in CNS regions affected by particular diseases but, most importantly, put special attention to the complicated reciprocal tuning connections prevailing between p53 and molecules considered in pathological hallmarks of these disorders. Natural and synthetic medications regulating p53 expression are regarded as well.


Asunto(s)
Enfermedades Neurodegenerativas/metabolismo , Proteína p53 Supresora de Tumor/metabolismo , Animales , Apoptosis/fisiología , Sistema Nervioso Central/metabolismo , Humanos , Neuronas/metabolismo
13.
Phytother Res ; 35(4): 1739-1753, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33051921

RESUMEN

Thymoquinone is a monoterpenoid compound, which is derived from volatile and fixed oil of Nigella sativa (Ranunculaceae). This phytochemical compound has several biological effects, including antioxidant, antibacterial, antineoplastic, nephroprotective, hepatoprotective, gastroprotective, neuroprotective, anti-nociceptive, and anti-inflammatory activities. Thymoquinone shows pharmacological activities, including anti-hepatocellular carcinoma, nephroprotection, neuroprotection, retina protection, gastroprotection, cardioprotection, anti-allergy, reproductive system protection, bladder protection, and respiratory protection. It was found that these beneficial effects are mostly related to modulation of the Nrf2 signaling pathway by blockage of Keap1, stimulating the expression of the Nrf2 gene, and inducing the nuclear translocation of Nrf2. In the present review, the therapeutic effects of thymoquinone are overviewed through the Nrf2 signaling pathway.


Asunto(s)
Benzoquinonas/uso terapéutico , Factor 2 Relacionado con NF-E2/metabolismo , Nigella sativa/química , Transducción de Señal/efectos de los fármacos , Animales , Benzoquinonas/farmacología , Humanos
14.
Biomed Pharmacother ; 133: 111088, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-33378982

RESUMEN

Alzheimer's disease (AD) is a neurodegenerative condition mostly communal in people of advanced years accompanying various dysfunctionalities especially cognitive impairments. A number of cellular damages, such as amyloid-beta aggregation, tau protein hyperphosphorylation, some neurotransmitter imbalances, apoptosis, oxidative stress, and inflammatory responses are responsible for AD incidence. As a reason for inadequate efficacy, side effects, and pharmacokinetic problems of conventional drugs used for AD, the discovery of novel therapeutic agents with multi-targeted potential is desirable. Protective properties of phytochemicals combat numerous diseases and their vast acceptance and demand in human beings encouraged scientists to assess their effective activities. Zingiber officinale, gingerol, shogaol, and borneol were evaluated against memory impairments. Online databases including; Web of Science, Scopus, Embase, Pubmed, ProQuest, ScienceDirect, and Cochrane Library were searched until 3th February 2020. In vitro, in vivo, and clinical studies are included after screening their eligibility. Mostly interventive mechanisms such as; oxidative stress, neuroinflammation, and apoptosis are described. Correlation between the pathogenesis of AD and signaling pathways is explicated. Results and scores of cognition measurements are clarified due to in vivo studies and clinical trials. Some traditional aspects of consuming ginger in AD are also mentioned in the present review. In accumulation ginger and its components possess great potency for improving and abrogating memory dysfunctions but conducting further studies to evaluate their pharmacological and pharmaceutical aspects is required.


Asunto(s)
Enfermedad de Alzheimer/tratamiento farmacológico , Encéfalo/efectos de los fármacos , Cognición/efectos de los fármacos , Disfunción Cognitiva/tratamiento farmacológico , Memoria/efectos de los fármacos , Nootrópicos/uso terapéutico , Extractos Vegetales/uso terapéutico , Zingiber officinale , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/fisiopatología , Enfermedad de Alzheimer/psicología , Animales , Apoptosis/efectos de los fármacos , Encéfalo/metabolismo , Encéfalo/patología , Encéfalo/fisiopatología , Disfunción Cognitiva/patología , Disfunción Cognitiva/fisiopatología , Disfunción Cognitiva/psicología , Modelos Animales de Enfermedad , Zingiber officinale/química , Humanos , Mediadores de Inflamación/metabolismo , Nootrópicos/aislamiento & purificación , Estrés Oxidativo/efectos de los fármacos , Extractos Vegetales/aislamiento & purificación
15.
Biomed Pharmacother ; 130: 110590, 2020 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32768885

RESUMEN

Honey and its phenolic compounds specifically chrysin are focused as nutritional supplements and likewise as valued phytochemicals, nutraceuticals, and phytopharmaceuticals alone, or adjuvant with some conventional medications to cause synergistic therapeutic or cytotoxic effects. Through the verified beneficial strategies combat several disturbances, phenolic compounds play fundamental functions in the avoidance and treatment of disorders. Oxidative stress, inflammation, and apoptosis are the three most imperative physiological reactions in the prevalence of numerous ailments. Honey, chrysin, and other phenolic compounds detected in honey can modify clinical conditions via modulation of these contrivances and correlated signaling pathways. The current study desires to review the therapeutic effects of honey and its allied molecular mechanisms. Evidenced-base studies show that honey would represent therapeutic potential against various types of cancer and tumor proliferation (colorectal cancer, breast cancer, bladder cancer, leukemia, glioma, hepatocellular cancer, pancreatic cancer, and melanoma), wounds, diabetes mellitus, neurological (depression, Parkinson disease, and Alzheimer's disease), respiratory, gastrointestinal (peptic ulcer and ulcerative colitis), cardiovascular disorders, renal injuries, liver diseases and many other kinds of physiological dysfunctionalities through various molecular mechanisms contributed with oxidative stress, inflammatory process, and apoptosis.


Asunto(s)
Miel , Fenoles/uso terapéutico , Animales , Antioxidantes/farmacología , Flavonoides/farmacología , Flavonoides/uso terapéutico , Humanos , Fenoles/farmacología
16.
Anal Bioanal Chem ; 412(12): 2927-2937, 2020 May.
Artículo en Inglés | MEDLINE | ID: mdl-32193589

RESUMEN

Homoserine lactones (HSLs) are signaling molecules synthesized by Gram-negative bacteria in order to communicate in a process termed "quorum sensing." Until recently, only the L-stereoisomers of HSLs were thought to be produced and able to incite quorum sensing. However, recent studies have shown that select Gram-negative bacteria additionally produce non-trivial amounts of D-HSLs which may also play a role in quorum sensing. Current methods for the separation of HSL enantiomers cannot effectively separate all classes of HSLs and its enantiomers. More robust methods of separation and detection of D-HSLs are necessary. We have developed rapid and selective methods using liquid chromatography (LC) and gas chromatography (GC) coupled with mass spectrometry (MS) which can simultaneously enantiomerically separate all classes of HSLs. The advantages of these methods are in the MS compatibility as well as the ability to enantiomerically separate all classes of HSLs in a single run. The first enantiomeric separations of oxo- and hydroxy-HSLs by GC-MS, through the use of N,O-bis(trimethylsilyl)trifluoroacetamide-derivatizing reagents are discussed. Graphical Abstract.


Asunto(s)
4-Butirolactona/análogos & derivados , Cromatografía Liquida/métodos , Cromatografía de Gases y Espectrometría de Masas/métodos , Percepción de Quorum , Espectrometría de Masas en Tándem/métodos , 4-Butirolactona/análisis , 4-Butirolactona/aislamiento & purificación , Estereoisomerismo
17.
Angew Chem Int Ed Engl ; 59(1): 192-196, 2020 01 02.
Artículo en Inglés | MEDLINE | ID: mdl-31652384

RESUMEN

We designed and demonstrated the unique abilities of the first gas chromatography-molecular rotational resonance spectrometer (GC-MRR). While broadly and routinely applicable, its capabilities can exceed those of high-resolution MS and NMR spectroscopy in terms of selectivity, resolution, and compound identification. A series of 24 isotopologues and isotopomers of five organic compounds are separated, identified, and quantified in a single run. Natural isotopic abundances of mixtures of compounds containing chlorine, bromine, and sulfur heteroatoms are easily determined. MRR detection provides the added high specificity for these selective gas-phase separations. GC-MRR is shown to be ideal for compound-specific isotope analysis (CSIA). Different bacterial cultures and groundwater were shown to have contrasting isotopic selectivities for common organic compounds. The ease of such GC-MRR measurements may initiate a new era in biosynthetic/degradation and geochemical isotopic compound studies.

18.
Chirality ; 31(9): 688-699, 2019 09.
Artículo en Inglés | MEDLINE | ID: mdl-31318099

RESUMEN

The enantiomeric excess of chiral starting materials is one of the important factors determining the enantiopurity of products in asymmetric synthesis. Fifty-one commercially available chiral reagents used as building blocks, catalysts, and auxiliaries in various enantioselective syntheses were assayed for their enantiomeric purity. The test results were classified within five impurities level (ie, <0.01%, 0.01%-0.1%, 0.1%-1%, 1%-10%, >10%). Previously from 1998 to 2013, several reports have been published on the enantiomeric composition of more than 300 chiral reagents. This series of papers is necessitated by the fact that new reagents are forthcoming and that the enantiomeric purity of the same reagent can vary from batch to batch and/or from supplier to supplier. This report presents chiral liquid chromatography (LC) and gas chromatography (GC) methods to separate enantiomers of chiral compounds and evaluate their enantiomeric purities. The accurate and efficient LC analysis was done using newly introduced superficially porous particle (SPP 2.7 µm) based chiral stationary phases (TeicoShell, VancoShell, LarihcShell-P, and NicoShell).

19.
Anal Chim Acta ; 1042: 155-164, 2018 Dec 26.
Artículo en Inglés | MEDLINE | ID: mdl-30428982

RESUMEN

Dicationic ionic liquids (DILs) are more and more accepted as a new class of high temperature and polar stationary phases for gas chromatography (GC). This study deals with the effect of seven different fluorosulfonyl derivatized anions associated with two dications: 1,3-di(3-methylimidazolium)-2-methylpropane [2mC3(mim)2], and 1,3-di(3-methylimidazolium)-isobutene [i-eneC4(mim)2]. Thermophysical properties of the 14 synthesized DILs were evaluated in terms of melting point, viscosity, and thermal stability. The optimal physicochemical properties of 13 DILs allowed preparing 13 GC capillary columns. Accordingly, the polarity and selectivity of the DILs were evaluated by determining the Rohrschneider-McReynolds constants and the equivalent chain lengths of C18 fatty acid methyl esters (FAMEs). The symmetrical fluoroalkylsulfonyl and the trifluorosulfonate anions seem to produce the most polar DILs. Compared to classical polyethyleneglycol phases, the DILs showed substantially decreased retention of apolar compounds and a much stronger retention of the polar ones. Unique selectivities were observed with unsaturated FAMEs, polyaromatic hydrocarbons, and bacterial specific FAMEs. The two applications presented included a biodiesel and bacterial FAME analyses.


Asunto(s)
Cromatografía de Gases/métodos , Ésteres/análisis , Ácidos Grasos/análisis , Líquidos Iónicos/química , Hidrocarburos Policíclicos Aromáticos/análisis , Aniones/química , Cationes/química , Estructura Molecular , Temperatura
20.
J Sep Sci ; 41(22): 4142-4148, 2018 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-30259657

RESUMEN

Three phosphonium-based dicationic ionic liquids were synthesized as bis(trifluoromethylsulfonyl) imide salts. The three dications had a nonyl spacer between two identical phosphonium-substituted groups. The three phosphonium moieties were dipropyl(phenyl), diphenyl(propyl), and diphenyl(toluyl). The physicochemical properties of the dicationic ionic liquids were appropriate to prepare 30 m capillary columns that were tested in gas chromatography. A unique selectivity compared to different polysiloxane or polar cyanosiloxane commercial columns was observed for selected mixes of phthalates, polyaromatic hydrocarbons, polychlorobiphenyls, and dioxins. Only minor selectivity variations were observed with the three dicationic ionic liquids. The different number of aromatic rings on the positively charged phosphonium group did not influence the dicationic ionic liquid selectivity significantly.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...