Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.379
Filtrar
1.
PLoS One ; 15(10): e0240421, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33031477

RESUMO

OBJECTIVE: To evaluate the microbial loading in aerosols produced after air-puff by non-contact tonometer (NCT) as well as the effect of alcohol disinfection on the inhibition of microbes and thus to provide suggestions for the prevention and control of COVID-19 in ophthalmic departments of hospitals or clinics during the great pandemics. METHODS: A cross-sectional study was carried out in this study. A NIDEK NCT was used for intraocular pressure (IOP) measurement for patients who visited Department of Ophthalmology in Qilu Hospital of Shandong University during March 18-25 2020. After ultra-violate (UV) light disinfection, the room air was sampled for 5 minutes. Before and after alcohol disinfection, the air samples and nozzle surface samples were respectively collected by plate exposure method and sterile moist cotton swab technique after predetermined times of NCT air-puff. Microbial colony counts were calculated after incubation for 48 hours. Finally, mass spectrometry was performed for the accurate identification of microbial species. RESULTS: Increased microbial colonies were detected from air samples close to NCT nozzle after air-puff compared with air samples at a distance of 1 meter from the nozzle (p = 0.001). Interestingly, none microbes were detected on the surface of NCT nozzle. Importantly, after 75% alcohol disinfection less microbes were detected in the air beside the nozzle (p = 0.003). Microbial species identification showed more than ten strains of microbes, all of which were non-pathogenic. CONCLUSION: Aerosols containing microbes were produced by NCT air-puff in the ophthalmic consultation room, which may be a possible virus transmission route in the department of ophthalmology during the COVID-19 pandemic. Alcohol disinfection for the nozzle and the surrounding air was efficient at decreasing the microbes contained in the aerosols and theoretically this prevention measure could also inhibit the virus. This will give guidance for the prevention of virus transmission and protection of hospital staff and patients.


Assuntos
Microbiologia do Ar , Álcoois/química , Infecções por Coronavirus/prevenção & controle , Desinfetantes/química , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Tonometria Ocular/métodos , Aerossóis/química , Betacoronavirus/fisiologia , China/epidemiologia , Infecções por Coronavirus/epidemiologia , Estudos Transversais , Hospitais , Humanos , Oftalmologia/métodos , Pneumonia Viral/epidemiologia
2.
Epidemiol Infect ; 148: e229, 2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32988431

RESUMO

The pandemic due to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has emerged as a serious global public health issue. Since the start of the outbreak, the importance of hand-hygiene and respiratory protection to prevent the spread of the virus has been the prime focus for infection control. Health regulatory organisations have produced guidelines for the formulation of hand sanitisers to the manufacturing industries. This review summarises the studies on alcohol-based hand sanitisers and their disinfectant activity against SARS-CoV-2 and related viruses. The literature shows that the type and concentration of alcohol, formulation and nature of product, presence of excipients, applied volume, contact time and viral contamination load are critical factors that determine the effectiveness of hand sanitisers.


Assuntos
Álcoois/química , Betacoronavirus/efeitos dos fármacos , Higienizadores de Mão/química , Higienizadores de Mão/normas , Álcoois/farmacologia , Betacoronavirus/química , Coronavirus/química , Coronavirus/efeitos dos fármacos , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/prevenção & controle , Contaminação de Medicamentos , Higienizadores de Mão/farmacologia , Humanos , Pandemias/prevenção & controle , Pneumonia Viral/epidemiologia , Pneumonia Viral/prevenção & controle
3.
J Chromatogr A ; 1629: 461508, 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-32858453

RESUMO

In the present document, we report the development of an analytical method consisting of a sequential direct-immersion/headspace solid-phase microextraction (DI-HS-SPME) followed by gas-phase chromatography and tandem mass spectrometry (GC-MS/MS) for simultaneous analysis of 4-chlorobenzyl alcohol, 2,6-dichlorobenzyl alcohol, 4-methoxybenzyl alcohol, 3,4-dimethoxybenzyl alcohol, pyridine, and 2,3-dimethylpyrazine in oilfield production waters. These compounds are under evaluation for use as phase-partitioning tracers in oil reservoirs. To the best of our knowledge, this is the first time SPME has been applied to the analysis of these compounds in production waters, or any other type of matrix where the compounds targeted are the base for a technical application. Relevant extraction parameters, such as the adsorbent phase of the fiber, direct immersion or headspace, addition of salt, temperature and time of extraction were investigated. The final optimal operation conditions consist on extracting 5 mL of sample at pH 9.0 with 1.8 g of NaCl with constant stirring during 5 minutes of DI-SPME followed by 15 minutes of HS-SPME at 70 °C using a DVB/CAR/PDMS (50/30 µm) fiber. The limits of quantification (LOQ), linearity, precision and accuracy of the method were evaluated. Analyses of the tracer compounds and recovery studies were also performed on production waters from 8 different oilfields of the Norwegian continental shelf. LOQs between 0.080 and 0.35 µg L-1 were obtained. The recovery yields of the method were consistently higher than 85% and RSDs less than 13%. None of the tracer compounds was found in the real samples processed, which is consistent with one of the requirements for an artificial tracer in an oilfield: absence or constant and low background in the traced fluid. The performance of the method developed, combined with its easiness to automate, introduce a new, accurate and cost-efficient technique to process the hundreds of samples required by an inter-well tracer test.


Assuntos
Cromatografia Gasosa-Espectrometria de Massas/métodos , Campos de Petróleo e Gás/química , Álcoois/análise , Álcoois/química , Álcoois/isolamento & purificação , Limite de Detecção , Pirazinas/análise , Pirazinas/química , Pirazinas/isolamento & purificação , Microextração em Fase Sólida , Temperatura
4.
J Chromatogr A ; 1626: 461341, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797822

RESUMO

The recognition and separation of polar chiral compounds are important technological challenges in separation science. Taking full advantage of the intrinsically chiral environment and multiple interactions featured by macrocycles, we designed the first example of porous methylated cyclodextrins-containing polymers (MP-CDPs) with three-dimensional (3D) chiral channels. The enantioselective recognition of (R)/(S)-1-phenylethylamine mixtures was realized with enantiomer excess (e.e.) >73% in only 3 min by using MP-CDPs as the adsorbent. The obtained MP-CDPs also serve as highly efficient liquid chromatographic stationary phases for separation of polar chiral compounds. The stationary phase can separate racemic alcohols and acids successfully. These chiral compounds can be separated within 8 min under normal-phase mode, and the resolution (RS) range from 1.76 to 3.00. Molecular simulations suggest that chiral recognition is a cooperative interaction based on multiple effects such as host-guest interaction, H-bond and size selection. These findings will provide novel chiral stationary phases for recognition and separation of polar chiral compounds in the fields of separation science and pharmaceutical industry.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Polímeros/química , beta-Ciclodextrinas/química , Álcoois/química , Ligação de Hidrogênio , Porosidade , Estereoisomerismo
5.
Nat Protoc ; 15(9): 2980-3008, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32839575

RESUMO

High-surface-area mesoporous materials expose abundant functional sites for improved performance in applications such as gas storage/separation, catalysis, and sensing. Recently, soft templates composed of amphiphilic surfactants and block copolymers have been used to introduce mesoporosity in various materials, including metals, metal oxides and carbonaceous compounds. In particular, mesoporous metals are attractive in electrocatalysis because their porous networks expose numerous unsaturated atoms on high-index facets that are highly active in catalysis. In this protocol, we describe how to create mesoporous metal films composed of gold, palladium, or platinum using block copolymer micelle templates. The amphiphilic block copolymer micelles are the sacrificial templates and generate uniform structures with tunable pore sizes in electrodeposited metal films. The procedure describes the electrodeposition in detail, including parameters such as micelle diameters, deposition potentials, and deposition times to ensure reproducibility. The micelle diameters can be controlled by swelling the micelles with different solvent mixtures or by using block copolymer micelles with different molecular weights. The deposition potentials and deposition times allow further control of the mesoporous structure and its thickness, respectively. Procedures for example applications are included: glucose oxidation, ethanol oxidation and methanol oxidation reactions. The synthetic methods for preparation of mesoporous metal films will take ~4 h; the subsequent electrochemical tests will take ~5 h for glucose sensing and ~3 h for alcohol oxidation reaction.


Assuntos
Ouro/química , Paládio/química , Platina/química , Álcoois/química , Catálise , Técnicas de Química Sintética , Eletroquímica , Interações Hidrofóbicas e Hidrofílicas , Micelas , Modelos Moleculares , Conformação Molecular , Oxirredução , Polímeros/química
6.
Nat Commun ; 11(1): 2890, 2020 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-32513962

RESUMO

Employment of sulfoxides as electrophiles in cross-coupling reactions remains underexplored. Herein we report a transition-metal-free cross-coupling strategy utilizing aryl(heteroaryl) methyl sulfoxides and alcohols to afford alkyl aryl(heteroaryl) ethers. Two drug molecules were successfully prepared using this protocol as a key step, emphasizing its potential utility in medicinal chemistry. A DFT computational study suggests that the reaction proceeds via initial addition of the alkoxide to the sulfoxide. This adduct facilitates further intramolecular addition of the alkoxide to the aromatic ring wherein charge on the aromatic system is stabilized by the nearby potassium cation. Rate-determining fragmentation then delivers methyl sulfenate and the aryl or heteroaryl ether. This study establishes the feasibility of nucleophilic addition to an appended sulfoxide as a means to form a bond to aryl(heteroaryl) systems and this modality is expected to find use with many other electrophiles and nucleophiles leading to new cross-coupling processes.


Assuntos
Álcoois/química , Éteres/química , Hidrocarbonetos Policíclicos Aromáticos/química , Sulfóxidos/química , Elementos de Transição/química , Carbono/química , Catálise , Química Farmacêutica/métodos , Compostos Heterocíclicos/química , Hidrocarbonetos Aromáticos/química , Metais/química , Modelos Químicos , Estrutura Molecular , Hidrocarbonetos Policíclicos Aromáticos/síntese química , Enxofre/química
7.
Nat Commun ; 11(1): 3080, 2020 06 17.
Artigo em Inglês | MEDLINE | ID: mdl-32555154

RESUMO

The exact chemical structure of non-crystallising natural products is still one of the main challenges in Natural Sciences. Despite tremendous advances in total synthesis, the absolute structural determination of a myriad of natural products with very sensitive chemical functionalities remains undone. Here, we show that a metal-organic framework (MOF) with alcohol-containing arms and adsorbed water, enables selective hydrolysis of glycosyl bonds, supramolecular order with the so-formed chiral fragments and absolute determination of the organic structure by single-crystal X-ray crystallography in a single operation. This combined strategy based on a biomimetic, cheap, robust and multigram available solid catalyst opens the door to determine the absolute configuration of ketal compounds regardless degradation sensitiveness, and also to design extremely-mild metal-free solid-catalysed processes without formal acid protons.


Assuntos
Produtos Biológicos/química , Hidrolases/química , Estruturas Metalorgânicas/química , Adsorção , Álcoois/química , Catálise , Cristalografia por Raios X , Glicólise , Hidrólise , Cinética , Metais , Conformação Molecular , Estrutura Molecular , Porosidade , Relação Estrutura-Atividade , Difração de Raios X
8.
Nature ; 584(7819): 69-74, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32512577

RESUMO

Enzymes are increasingly explored for use in asymmetric synthesis1-3, but their applications are generally limited by the reactions available to naturally occurring enzymes. Recently, interest in photocatalysis4 has spurred the discovery of novel reactivity from known enzymes5. However, so far photoinduced enzymatic catalysis6 has not been used for the cross-coupling of two molecules. For example, the intermolecular coupling of alkenes with α-halo carbonyl compounds through a visible-light-induced radical hydroalkylation, which could provide access to important γ-chiral carbonyl compounds, has not yet been achieved by enzymes. The major challenges are the inherent poor photoreactivity of enzymes and the difficulty in achieving stereochemical control of the remote prochiral radical intermediate7. Here we report a visible-light-induced intermolecular radical hydroalkylation of terminal alkenes that does not occur naturally, catalysed by an 'ene' reductase using readily available α-halo carbonyl compounds as reactants. This method provides an efficient approach to the synthesis of various carbonyl compounds bearing a γ-stereocentre with excellent yields and enantioselectivities (up to 99 per cent yield with 99 per cent enantiomeric excess), which otherwise are difficult to access using chemocatalysis. Mechanistic studies suggest that the formation of the complex of the substrates (α-halo carbonyl compounds) and the 'ene' reductase triggers the enantioselective photoinduced radical reaction. Our work further expands the reactivity repertoire of biocatalytic, synthetically useful asymmetric transformations by the merger of photocatalysis and enzyme catalysis.


Assuntos
Alcenos/química , Alcenos/metabolismo , Hidrogênio/química , Hidrogênio/metabolismo , Luz , Oxirredutases/metabolismo , Processos Fotoquímicos/efeitos da radiação , Álcoois/química , Álcoois/metabolismo , Alquilação/efeitos da radiação , Biocatálise/efeitos da radiação , Biomassa , Carboxiliases/metabolismo , Flavinas/metabolismo , Modelos Químicos , Modelos Moleculares , Estereoisomerismo
9.
Nat Commun ; 11(1): 2756, 2020 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-32488003

RESUMO

Trifluoroethanol and difluoroethanol units are important motifs in bioactive molecules, but the methods to direct incorporate these units are limited. Herein, we report two organosilicon reagents for the transfer of trifluoroethanol and difluoroethanol units into molecules. Through intramolecular C-Si bond activation by alkoxyl radicals, these reagents were applied in allylation, alkylation and alkenylation reactions, enabling efficient synthesis of various tri(di)fluoromethyl group substituted alcohols. The broad applicability and general utility of the approach are highlighted by late-stage introduction of these fluoroalkyl groups to complex molecules, and the synthesis of antitumor agent Z and its difluoromethyl analog Z'.


Assuntos
Etanol/análogos & derivados , Etanol/química , Compostos de Organossilício/química , Trifluoretanol/química , Álcoois/química , Alquilação , Técnicas de Química Sintética , Indicadores e Reagentes/química , Estrutura Molecular
10.
Int J Pharm ; 584: 119431, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: covidwho-277012

RESUMO

The world is facing a medical crisis amid the CoViD-19 pandemic and the role of adequate hygiene and hand sanitisers is inevitable in controlling the spread of infection in public places and healthcare institutions. There has been a great surge in demand for hand sanitisation products leading to shortages in their supply. A consequent increase of substandard products in the market has raised safety concerns. This article, therefore, presents a critical review of hand sanitation approaches and products available on the market in light of the scientific evidence available to date. This review also provides a range of hand sanitisation product formulations, and manufacturing instructions to allow for extemporaneous preparations at the community and hospital pharmacies during this urgent crisis. In addition, this emergent situation is expected to continue, hence hand sanitisers will be in demand for an extended time, and the availability and purchase of substandard products on the market create an ongoing safety concern. Therefore, this article shall also provide various commercial organisations, interested in stepping forward the production and marketing of hand sanitisers, with a guide on the development of products of standardised ingredients and formulations.


Assuntos
Álcoois/química , Infecções por Coronavirus/prevenção & controle , Desinfetantes/química , Composição de Medicamentos , Desinfecção das Mãos/métodos , Higiene das Mãos/métodos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Desinfetantes/uso terapêutico , Humanos
11.
Int J Pharm ; 584: 119431, 2020 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-32461194

RESUMO

The world is facing a medical crisis amid the CoViD-19 pandemic and the role of adequate hygiene and hand sanitisers is inevitable in controlling the spread of infection in public places and healthcare institutions. There has been a great surge in demand for hand sanitisation products leading to shortages in their supply. A consequent increase of substandard products in the market has raised safety concerns. This article, therefore, presents a critical review of hand sanitation approaches and products available on the market in light of the scientific evidence available to date. This review also provides a range of hand sanitisation product formulations, and manufacturing instructions to allow for extemporaneous preparations at the community and hospital pharmacies during this urgent crisis. In addition, this emergent situation is expected to continue, hence hand sanitisers will be in demand for an extended time, and the availability and purchase of substandard products on the market create an ongoing safety concern. Therefore, this article shall also provide various commercial organisations, interested in stepping forward the production and marketing of hand sanitisers, with a guide on the development of products of standardised ingredients and formulations.


Assuntos
Álcoois/química , Infecções por Coronavirus/prevenção & controle , Desinfetantes/química , Composição de Medicamentos , Desinfecção das Mãos/métodos , Higiene das Mãos/métodos , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Desinfetantes/uso terapêutico , Humanos
12.
Adv Exp Med Biol ; 1195: 189-198, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32468477

RESUMO

In the present work, new indole derivatives, i.e., 5-[N,N-di alkyl amino alkoxy] azaindole 2,3- di-one derivatives, are synthesized and characterized. These compounds were subjected to acute toxicity and then screened for antiepileptic activity on maximal electroshock seizure (MES) model in albino Wistar rats. In that study 5-[2-dimethyl amino ethoxy] Azaindole-3-hydrazone,2-one and 5-[2- dimethyl amino ethoxy] Azaindole 2-one,3-thiothiosemicarbazone(IIIa) showed good antiepileptic activity and less neurotoxicity compared to phenytoin. The purpose of the present study is to investigate the effect of 5-[2-dimethyl amino ethoxy] Indole 2,3- di one and 5-[2-dimethyl amino ethoxy] Azaindole 2-one,3-thiosemicarbazone(IIIa) derivatives on biogenic amines concentrations in rat brain after induction of seizures by MES method. The aim of study was relationship between seizure activities and altered the monoamines such as Noradrenaline (NA), Dopamine (DA), Serotonin (5-HT) in forebrain of rats in MES seizure models. In MES model, study of 5-[2-dimethyl amino ethoxy] Azaindole 3-hydrazone,2-one(Va) and 5-[2-dimethyl amino ethoxy]Azaindole 2-one,3-thiosemicarbazone(IIIa) (100 mg/kg) showed significant restoration of the decreased levels of brain monoamines such as noradrenaline, dopamine, and 5-hydroxytryptamine. Thus, this study suggests that 5-[2-Dimethyl amino ethoxy] Azaindole 3-hydrazone,2-one (V) and 5-[2-dimethyl amino ethoxy] Azaindole 2-one,3-thiosemicarbazone (IIIa) increased the monoamines on rat brain, which may decrease the susceptibility to MES-induced seizure in rats.


Assuntos
Anticonvulsivantes/síntese química , Anticonvulsivantes/uso terapêutico , Indóis/síntese química , Indóis/uso terapêutico , Tiossemicarbazonas/síntese química , Tiossemicarbazonas/uso terapêutico , Álcoois/síntese química , Álcoois/química , Álcoois/farmacologia , Álcoois/uso terapêutico , Animais , Anticonvulsivantes/química , Anticonvulsivantes/farmacologia , Modelos Animais de Doenças , Hidrazonas/síntese química , Hidrazonas/química , Hidrazonas/farmacologia , Hidrazonas/uso terapêutico , Indóis/química , Indóis/farmacologia , Ratos , Ratos Wistar , Convulsões/tratamento farmacológico , Tiossemicarbazonas/química , Tiossemicarbazonas/farmacologia
13.
Chem Pharm Bull (Tokyo) ; 68(3): 258-264, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32115533

RESUMO

Oxo-octadecadienoic acids (OxoODEs) act as peroxisome proliferator-activated receptor (PPAR) agonists biologically, and are known to be produced in the lipoxygenase/linoleate system. OxoODEs seem to originate from the linoleate alkoxyl radicals that are generated from (E/Z)-hydroperoxy octadecadienoic acids ((E/Z)-HpODEs) by a pseudoperoxidase reaction that is catalyzed by ferrous lipoxygenase. However, the mechanism underlying the conversion of alkoxyl radical into OxoODE remains obscure. In the present study, we confirmed that OxoODEs are produced in the lipoxygenase/linoleate system in an oxygen-dependent manner. Interestingly, we revealed a correlation between the (E/Z)-OxoODEs content and the (E/E)-HpODEs content in the system. (E/E)-HpODEs could have been derived from (E/E)-linoleate peroxyl radicals, which are generated by the reaction between a free linoleate allyl radical and an oxygen molecule. Notably, the ferrous lipoxygenase-linoleate allyl radical (LOx(Fe2+)-L·) complex, which is an intermediate in the lipoxygenase/linoleate system, tends to dissociate into LOx(Fe2+) and a linoleate allyl radical. Subsequently, LOx(Fe2+) converts (E/Z)-HpODEs to an (E/Z)-linoleate alkoxyl radical through one-electron reduction. Taken together, we propose that (E/Z)-OxoODEs and (E/E)-HpODEs are produced through radical-radical dismutation between (E/Z)-linoleate alkoxyl radical and (E/E)-linoleate peroxyl radical. Furthermore, the production of (E/Z)-OxoODEs and (E/E)-HpODEs was remarkably inhibited by a hydrophobic radical scavenger, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO). On the contrary, water-miscible radical scavengers, 4-hydroxyl-2,2,6,6-tetramethylpiperidine 1-oxyl (OH-TEMPO) and 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrroline-N-oxyl (CmΔP) only modestly or sparingly inhibited the production of (E/Z)-OxoODEs and (E/E)-HpODEs. These facts indicate that the radical-radical dismutation between linoleate alkoxyl radical and linoleate peroxyl radical proceeds in the interior of micelles.


Assuntos
Álcoois/metabolismo , Ácidos Graxos/metabolismo , Lipoxigenases/metabolismo , Oxigênio/metabolismo , Peróxidos/metabolismo , Álcoois/química , Biocatálise , Ácidos Graxos/química , Estrutura Molecular , Oxigênio/química , Peróxidos/química
14.
J Chromatogr A ; 1620: 460987, 2020 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-32115231

RESUMO

It is critical to determine the chiral impurity profile of pharmaceutical compounds. The rising trend of drug candidates bearing multiple chiral centers has aggravated the analytical challenges. The traditional chiral HPLC methods can take gruelingly long time to develop yet may not offer sufficient resolution for all stereoisomers. A fast analytical strategy with a high success rate is in urgent demand for compounds with multiple chiral centers. In this study, we have developed an effective and fast multiple heart-cutting (MHC) multicolumn two-dimensional liquid chromatography (LC-mLC) platform approach. The m in the name of LC-mLC highlights the employment of multiple chiral columns with different chiral selectors and mobile phases in the second dimension (2D) within the same run. A short achiral HPLC method in the first dimension (1D) allows the separation of diastereomers and other achiral impurities, followed by 2D analysis enabling different chiral columns and different mobile phases on each coeluted 1D peak for maximum resolution. This LC-mLC strategy breaks down the complex multiple-chiral-center separation problems into simple individual one-chiral-center separation, which dramatically reduces chiral method development time and sample analysis turnaround. Its versatile nature and fast turnaround approach have made it a highly efficient strategy to enable quick stereoselective synthetic route development. This platform LC-mLC strategy has been successfully demonstrated in separating eight stereoisomers for a pharmaceutical compound with 3 chiral centers, within total method development time of less than 2 hours and a final analysis time of less than 24 min, including column equilibration time. It was also proved highly efficient in separating multiple chiral and achiral components in an in-process sample containing structurally similar starting materials, intermediates, side products and multiple stereoisomers of the product with 3 chiral centers, with minimal method development time.


Assuntos
Cromatografia Líquida/métodos , Álcoois/química , Reprodutibilidade dos Testes , Estereoisomerismo
15.
Artif Cells Nanomed Biotechnol ; 48(1): 560-571, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32046511

RESUMO

In this paper, the first bio-nano colloid including manganese oxide nanoparticles and copper nanocomplex in the presence of Amaranthus spinosus as one unwanted plant was prepared (Mn3O4/CuL bio-nanocolloid). As-prepared bio nanocolloid was analysed completely by different techniques such as FT-IR, ICP-AES, SEM, EDX, TEM and elemental analysis to have the size, structure, morphology and elements in this compound. This bio-nanocolloid showed high catalytic activity towards green oxidation reactions of alcohols using hydrogen peroxide under solvent free conditions. The longevity, easy and practical recoverability of the solid catalyst was also confirmed for six times. The natural starting material for a long-term stability catalyst preparation, using ideal oxidant (H2O2), solventless and easy work up show the great potential in scalability for actual industries applications.


Assuntos
Amaranthus/química , Cobre/química , Química Verde , Compostos de Manganês/química , Nanocompostos/química , Óxidos/química , Álcoois/química , Catálise , Coloides , Peróxido de Hidrogênio/química , Nanopartículas Metálicas/química , Oxirredução , Bases de Schiff
16.
Molecules ; 25(3)2020 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-32050493

RESUMO

The development of sustainable processes and products through innovative catalytic materials and procedures that allow a better use of resources is undoubtedly one of the most significant issues facing researchers nowadays. Environmental and economically advanced catalytic processes for selective oxidation of alcohols are currently focused on designing new catalysts able to activate green oxidants (dioxygen or peroxides) and applying unconventional conditions of sustainable significance, like the use of microwave irradiation as an alternative energy source. This short review aims to provide an overview of the recently (2015-2020) discovered homogeneous aerobic and peroxidative oxidations of primary and secondary alcohols catalyzed by copper complexes, highlighting new catalysts with potential application in sustainable organic synthesis, with significance in academia and industry.


Assuntos
Álcoois/química , Cobre/química , Química Verde , Oxidantes/química , Oxigênio/química , Peróxidos/química , Catálise , Humanos , Micro-Ondas , Estrutura Molecular , Oxirredução
17.
Molecules ; 25(3)2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32041136

RESUMO

A series of new hyperbranched aliphatic poly(ß-thioether ester)s were prepared by the enzymatic ring-opening polycondensation of 1,4-oxathiepan-7-one (OTO) and AB2/ABB' comonomer with acid-labile ß-thiopropionate groups. Two kinds of comonomers, methyl 3-((3-hydroxy-2-(hydroxymethyl)propyl)thio)propanoate (HHTP) and methyl 3-((2,3-dihydroxypropyl)thio)propanoate (DHTP), with different primary alcohols and secondary alcohols, were synthesized by thiol-ene click chemistry and thiol-ene Michael addition, respectively. Immobilized lipase B from Candida antarctica (CALB), Novozym 435, was used as the catalyst. The random copolymers were characterized by 1H-NMR, 13C-NMR, GPC, TGA, and DSC. All branched copolyesters had high molecular weights over 15,000 Da with narrow polydispersities in the range of 1.75-2.01 and were amorphous polymers. Their degradation properties under acidic conditions were also studied in vitro. The polymeric nanoparticles of hyperbranched poly(ß-thioether ester)s were successfully obtained and showed good oxidation-responsive properties, indicating their potential for biomedical applications.


Assuntos
Lipase/química , Poliésteres/química , Polímeros/química , Álcoois/química , Materiais Biocompatíveis/química , Candida/enzimologia , Catálise , Enzimas Imobilizadas/química , Proteínas Fúngicas/química , Nanopartículas/química , Oxirredução , Fenantrenos/química
18.
Molecules ; 25(3)2020 Feb 06.
Artigo em Inglês | MEDLINE | ID: mdl-32041345

RESUMO

The cascade process of a dynamic chirality transmission from the permanent chirality center to the stereodynamic triphenylmethyl group has been studied for series of optically active trityl derivatives. The structural analysis, carried out with the use of complementary methods, enabled us to determine the mechanism of chirality transfer. The process of chirality transmission involves a set of weak but complementary electrostatic interactions. The induction of helicity in a trityl propeller is revealed by rising non-zero cotton effects in the area of trityl UV-absorption. The presence of an additional stereogenic center in close proximity to the trityl-containing stereogenic center significantly affects the sign and, to a lesser extent, magnitude of the respective cotton effects. Despite the bulkiness of the trityl, in the crystalline phase, the molecules under study strictly fill the space. In the crystal, molecules form aggregates stabilized by OH•••O hydrogen bonds. However, the presence of two trityl groups precludes formation of OH•••O hydrogen bonding. Additionally, the trityl group seems to be responsible for the formation of the solid solutions by e.g., racemates of trans- and cis-2-tritylcyclohexanol. Therefore, the trityl group acts as a supramolecular protective group, which in turn can be used in the crystal engineering.


Assuntos
Álcoois/química , Dicroísmo Circular , Ligação de Hidrogênio , Estrutura Secundária de Proteína , Estereoisomerismo
19.
Molecules ; 25(3)2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-32019185

RESUMO

An efficient nickel-catalyzed removal of alkene protection group under mild condition with high functional group tolerance through chain walking process has been established. Not only phenolic ethers, but also alcoholic ethers can be tolerated with the retention of stereocenter adjacent to hydroxyl group. The new reaction brings the homoallyl group into a start of new type of protecting group.


Assuntos
Álcoois/química , Alcenos/química , Níquel/química , Fenóis/química , Catálise , Estrutura Molecular
20.
Sci Rep ; 10(1): 1655, 2020 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-32015393

RESUMO

Odorant receptors expressed at the peripheral olfactory organs are key proteins for animal volatile sensing. Although they determine the odor space of a given species, their functional characterization is a long process and remains limited. To date, machine learning virtual screening has been used to predict new ligands for such receptors in both mammals and insects, using chemical features of known ligands. In insects, such approach is yet limited to Diptera, whereas insect odorant receptors are known to be highly divergent between orders. Here, we extend this strategy to a Lepidoptera receptor, SlitOR25, involved in the recognition of attractive odorants in the crop pest Spodoptera littoralis larvae. Virtual screening of 3 million molecules predicted 32 purchasable ones whose function has been systematically tested on SlitOR25, revealing 11 novel agonists with a success rate of 28%. Our results show that Support Vector Machine optimizes the discovery of novel agonists and expands the chemical space of a Lepidoptera OR. More, it opens up structure-function relationship analyses through a comparison of the agonist chemical structures. This proof-of-concept in a crop pest could ultimately enable the identification of OR agonists or antagonists, capable of modifying olfactory behaviors in a context of biocontrol.


Assuntos
Proteínas de Insetos/agonistas , Receptores Odorantes/agonistas , Spodoptera/fisiologia , Acetofenonas/química , Acetofenonas/farmacologia , Álcoois/química , Álcoois/farmacologia , Aldeídos/química , Aldeídos/farmacologia , Animais , Simulação por Computador , Relação Dose-Resposta a Droga , Proteínas de Drosophila/agonistas , Proteínas de Drosophila/química , Avaliação Pré-Clínica de Medicamentos/métodos , Avaliação Pré-Clínica de Medicamentos/estatística & dados numéricos , Proteínas de Insetos/química , Ligantes , Odorantes/análise , Estudo de Prova de Conceito , Receptores Odorantes/química , Máquina de Vetores de Suporte
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA