Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.104
Filtrar
1.
J Chromatogr A ; 1628: 461438, 2020 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-32822978

RESUMO

A fast, simple, environmentally friendly and sensitive on-line concentration method using microemulsion system as background solution (BGS) was developed for the trace detection of propazine, atrazine, simazine in food samples. The electrokinetic injection assisted micelle to cyclodextrin stacking (MCDS) was designed for the enrichment of target compounds. The factors affected enrichment performance, such as the kind of CDs, the amount of CDs, the concentration of methanol in BGS, the concentration of micelle in sample matrix, the concentration of phosphoric acid in BGS and the sample injection time were optimized. The optimized electrophoretic condition was obtained as following: 50 mM α-CD, 20 mM SDS in sample matrix., 80 mM PA and 20% MeOH (v/v) in BGS, sample solution by electrokinetic injection at -10 kV for 80 s. Under the optimized conditions described above, the linear range was 0.1-20 ug/mL with a good linear relationship with a correlation coefficient (r) ≥ 0.9985. The SEFs for the propazine, atrazine, simazine were found to be 123, 85 and 62 respectively. The proposed MCDS-MEEKC method provided an efficient method for trace analysis of triazine herbicides in honey and dendrobium officinale samples.


Assuntos
Técnicas de Química Analítica/métodos , Cromatografia Capilar Eletrocinética Micelar , Ciclodextrinas/química , Herbicidas/isolamento & purificação , Micelas , Triazinas/isolamento & purificação , Atrazina , Ácidos Fosfóricos , Simazina
2.
J Chromatogr A ; 1626: 461383, 2020 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-32797856

RESUMO

The potential of Micellar Electrokinetic Chromatography to achieve enantiomeric separations is reviewed in this article. The separation principles and the most frequently employed separation strategies to achieve chiral separations by Micellar Electrokinetic Chromatography are described. The use of chiral micellar systems alone or combined with other micellar systems or chiral selectors, as well as of mixtures of achiral micellar systems with chiral selectors is discussed together with the effect of different additives present in the separation medium. Indirect methods based on the derivatization of analytes with chiral derivatizing reagents and the use of achiral micelles are also considered. Preconcentration techniques employed to improve sensitivity and the main approaches developed to facilitate the coupling with Mass Spectrometry are included. The most recent and relevant methodologies developed by chiral Micellar Electrokinetic Chromatography and their applications in different fields are presented.


Assuntos
Cromatografia Capilar Eletrocinética Micelar/métodos , Aminoácidos/química , Ciclodextrinas/química , Análise de Alimentos , Espectrometria de Massas , Oryza/química , Oryza/metabolismo , Estereoisomerismo , Vinho/análise
3.
J Chromatogr A ; 1627: 461375, 2020 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-32823120

RESUMO

Since decades, cyclodextrins are one of the most powerful selectors in chiral capillary electrophoresis for the enantioseparation of diverse organic compounds. This review concerns papers published over the last decade (from 2009 until nowadays), dealing with the capillary electrophoretic application of single isomer cyclodextrin derivatives in chiral separations. Following a brief overview of their synthetic approaches, the inventory of the neutral, negatively and positively charged (including both permanently ionic and pH-tunable ionizable substituents) and zwitterionic CD derivatives is presented, with insights to underlying structural aspects by NMR spectroscopy and molecular modeling. CE represents an ideal tool to study the weak, non-covalent supramolecular interactions. The published methods are reviewed in the light of enantioselectivity, enantiomer migration order and the fine-tuning of enantiodiscrimination by the substitution pattern of the single entity selector molecules, which is hardly possible for their randomly substituted counterparts. All the reviewed publications herein support that cyclodextrin-based chiral capillary electrophoresis seems to remain a popular choice in pharmaceutical and biomedical analysis.


Assuntos
Ciclodextrinas/química , Eletroforese Capilar/métodos , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estereoisomerismo
4.
AAPS PharmSciTech ; 21(5): 183, 2020 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-32632576

RESUMO

Pulmonary drug delivery is a noninvasive therapeutic approach that offers many advantages including localized drug delivery and higher patient compliance. As with all formulations, the low aqueous solubility of a drug often poses a challenge in the formulation development. Thus, strategies such as cyclodextrin (CD) complexation have been utilized to overcome this challenge. Resveratrol (RES), a natural stilbene, has shown abundant anti-cancer properties. Due to many drawbacks of conventional chemotherapeutics, RES has been proposed as an emerging alternative with promising pharmacological effects. However, RES has limited therapeutic applications due to low water solubility, chemical stability, and bioavailability. This study was aimed at developing an inhalable therapy that would increase the aqueous solubility and stability of RES by complexation with sulfobutylether-ß-cyclodextrin (SBECD). Phase solubility profiles indicated an optimal stoichiometric inclusion complex at 1:1 (SBECD:RES) ratio for formulation considerations. Physiochemical characterizations were performed to analyze CD-RES. Stability studies at pH 7.4 and in plasma indicated significant improvement in RES stability after complexation, with a much longer half-life. The mass median aerodynamic diameter (MMAD) of CD-RES was 2.6 ± 0.7 µm and fine particle fraction (FPF) of 83.4 ± 3.0% are suitable for pulmonary delivery and efficient deposition. Lung cancer was selected as the respiratory model disease, owing to its high relevance as the major cause of cancer deaths worldwide. Cell viability studies in 5 non-small-cell-lung-cancer (NSCLC) cell lines suggest CD-RES retained significant cytotoxic potential of RES. Taken together, CD-RES proves to be a promising inhalation treatment for NSCLC.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Ciclodextrinas/química , Neoplasias Pulmonares/tratamento farmacológico , Resveratrol/administração & dosagem , Administração por Inalação , Disponibilidade Biológica , Portadores de Fármacos/metabolismo , Estabilidade de Medicamentos , Humanos , Pulmão/metabolismo , Solubilidade
5.
Int J Pharm ; 588: 119689, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32717282

RESUMO

A handful of singular structures and laws can be observed in nature. They are not always evident but, once discovered, it seems obvious how to take advantage of them. In chemistry, the discovery of reproducible patterns stimulates the imagination to develop new functional materials and technological or medical applications. Two clear examples are helical structures at different levels in biological polymers as well as ring and spherical structures of different size and composition. Rings are intuitively observed as holes able to thread elongated structures. A large number of real and fictional stories have rings as inanimate protagonists. The design, development or just discovering of a special ring has often been taken as a symbol of power or success. Several examples are the Piscatory Ring wore by the Pope of the Catholic Church, the NBA Championship ring and the One Ring created by the Dark Lord Sauron in the epic story The Lord of the Rings. In this work, we reveal the power of another extremely powerful kind of rings to fight against the pandemic which is currently affecting the whole world. These rings are as small as ~1 nm of diameter and so versatile that they are able to participate in the attack of viruses, and specifically SARS-CoV-2, in a large range of different ways. This includes the encapsulation and transport of specific drugs, as adjuvants to stabilize proteins, vaccines or other molecules involved in the infection, as cholesterol trappers to destabilize the virus envelope, as carriers for RNA therapies, as direct antiviral drugs and even to rescue blood coagulation upon heparin treatment. "One ring to rule them all. One ring to find them. One ring to bring them all and in the darkness bind them." J. R. R. Tolkien.


Assuntos
Betacoronavirus/efeitos dos fármacos , Infecções por Coronavirus/tratamento farmacológico , Ciclodextrinas/química , Ciclodextrinas/farmacologia , Nanoestruturas , Pneumonia Viral/tratamento farmacológico , Betacoronavirus/metabolismo , Coagulação Sanguínea/efeitos dos fármacos , Infecções por Coronavirus/prevenção & controle , Portadores de Fármacos/química , Portadores de Fármacos/farmacologia , Estabilidade de Medicamentos , Excipientes/química , Excipientes/farmacologia , Pandemias/prevenção & controle , Pneumonia Viral/prevenção & controle , Vacinas Virais/química , Vacinas Virais/farmacologia
6.
Food Chem ; 333: 127495, 2020 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-32663747

RESUMO

Various pesticides employed in modern agriculture result in large amounts of pesticide residues in agricultural production, greatly threatening human health. Herein, we report a facile approach to fabricate a reduced graphene oxide/cyclodextrin modified glassy carbon electrode (rGO/CD/GCE) for the sensitive electrochemical sensing of imidacloprid (IDP). Three different modified electrodes using CDs (α-, ß-, γ-CD) were fabricated, and their electrochemical performance was further studied. The results demonstrate that α-CD possesses the best signal amplification for IDP. Compared with wet-chemical synthesis of rGO/CDs (W-rGO/CDs), the electrochemical synthesis of rGO/CDs (E-rGO/CDs) produced sensors that showed better performance for IDP sensing. Taking advantage of prepared E-rGO/α-CD nanocomposite, the fabricated sensor offered a low detection limit (0.02 µM) with a wider linear range (0.5-40 µM) and long-term stability. The new sensor was successfully applied for the detection of IDP in brown rice, providing a new technique for efficient and convenient monitoring of pesticide residues in food.


Assuntos
Ciclodextrinas/química , Técnicas Eletroquímicas/métodos , Grafite/química , Inseticidas/análise , Neonicotinoides/análise , Nitrocompostos/análise , Oryza/química , Carbono/química , Técnicas Eletroquímicas/instrumentação , Eletrodos , Contaminação de Alimentos/análise , Nanocompostos/química , Oxirredução , Sementes/química , Sensibilidade e Especificidade
7.
J Chromatogr A ; 1623: 461209, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505293

RESUMO

In most cases, determination of binding constant for analyte-cyclodextrin complexes in capillary electrophoresis is investigated by affinity capillary electrophoresis using a UV detector (ACE-UV). The limitations induced by the UV-detector include : (i) the difficulty of dealing with poor chromogenic analytes and more generally with any analyte presenting strong affinity towards the cyclodextrin (CD), i.e. for which the prerequisite to work with analyte concentration much smaller than those of the CD is difficult to fulfill (ii) the impossibility of studying non-chromogenic analyte. In this paper, two simple methodologies were developed to overcome these limitations. Regarding the analytes which present poor UV-absorbance and/or very high CD-affinity, a methodology using an algorithmic data treatment and taking into account the real analyte concentration in the capillary at the determined migration times allows to correctly estimate the binding constants, even if the experimental prerequisite ([analyte]<<[CD]) is not complied. Moreover, it is proved that classical linearization treatment by picking the migration time of the infinite diluted analytes (at the start of the peak) also provide satisfactory results. Regarding UV-transparent analyte, a competitive methodology combined with algorithmic data treatment allows the determination of their affinity towards cyclodextrins. Last, the applicability of the described competitive method is extended to the study of interaction between two neutral partners, which is another well-known limitation of ACE.


Assuntos
Ciclodextrinas/química , Eletroforese Capilar/métodos , Raios Ultravioleta , Ibuprofeno/análise , Cinética , Modelos Lineares , Termodinâmica
8.
J Chromatogr A ; 1623: 461158, 2020 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-32505274

RESUMO

In the present study, the enantioseparation of the ll- and dd-enantiomers of the dipeptides Ala-Phe, Ala-phenylglycine (Phg), Ala-homoPhe, Ala-ß-Phe, Gly-Phe and ß-Ala-Phe was studied by capillary electrophoresis in the presence of native α-, ß- and γ-cyclodextrin (CD) as well as their methyl and hydroxypropyl derivatives. Separations were performed under standardized conditions in fused-silica capillaries at pH 2.5, 3.5 and 9.5. All analyte enantiomers could be separated at acidic pH under at least one of the experimental conditions. ß-CDs proved to be more universal chiral selectors than α- and γ-CDs. Only few alkaline conditions led to an enantioseparation. For a given dipeptide, the enantiomer migration order depended on the type of CD with regard to cavity size and degree of substitution. Little effect was found with regard to the structure of the dipeptides. pH-dependent reversal of the enantiomer migration order upon increasing the pH from 2.5 to 3.5 was observed for all dipeptides with at least one of the ß-CD derivatives. In the case of ß-CD, analysis of the complexation constants and the apparent limiting mobilities of the diastereomeric peptide enantiomer-CD complexes revealed, that the enantiomer migration order of Ala-Phe, Ala-homoPhe and Ala-ß-Phe was determined by the stereoselective complexation by ß-CD at pH 2.5. At pH 3.5 opposite chiral recognition of the enantiomers by ß-CD was found for Ala-Phe and Ala-ß-Phe resulting in the reversed migration order. In contrast, chiral recognition did not change in the case of Ala-homoPhe, but reversal of the enantiomer migration order was based on the apparent mobility of the diastereomeric analyte-CD complexes.


Assuntos
Ciclodextrinas/química , Dipeptídeos/química , Eletroforese Capilar/métodos , Dipeptídeos/isolamento & purificação , Concentração de Íons de Hidrogênio , Estereoisomerismo
9.
Chemosphere ; 259: 127439, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32593825

RESUMO

The presence of emerging micropollutants and dyes in water resource has raised global concern about their intense effects to aquatic environments, ecosystem and human health in general. So far, various adsorbents have been suggested for reducing the levels of bisphenol A, methylene blue and neutral red contamination in wastewaters. However, a number of these adsorbents seemed to have low adsorptive capacities and regeneration performances. In view of these, batch experiment was performed to decontaminate these pollutants from aqueous solutions using an optimized bagasse-ß-cyclodextrin polymer (SB-ß-CD). Characterization studies of SB-ß-CD were performed using FTIR, pH point of zero charge, XRD and BET methods. Adsorption of BPA, MB and NR was favored at lower temperature (298 K) and pH of 7.0, 9.0 and 6.0, respectively. The maximum adsorption capacity of BPA, MB and NR at 298 K was 121, 963 and 685 mg g-1, respectively. Hydrogen bonding through host-guest inclusion and electrostatic interactions could respectively attribute to uptake of BPA and MB/NR onto SB-ß-CD. Adsorption kinetics of three pollutants followed pseudo-second-order model. Langmuir and Freundlich models were fitted to describe the adsorption of BPA and MB/NR, respectively. Thermodynamic parameters confirmed the occurrence of physical adsorption which is spontaneous and exothermic in nature. SB-ß-CD loaded with BPA and MB/NR was certainly reused by 75% ethanol and 0.1 mol L-1 HCl solutions, respectively. Novel SB-ß-CD showed better adsorptive capacity and regeneration performances; consequently can offers practical application for removal of BPA, MB and NR from wastewaters.


Assuntos
Compostos Benzidrílicos/química , Celulose/química , Ciclodextrinas/química , Azul de Metileno/química , Vermelho Neutro/química , Fenóis/química , Adsorção , Ecossistema , Polímeros , Poluentes Químicos da Água/análise , Purificação da Água/métodos , beta-Ciclodextrinas
10.
Chemosphere ; 250: 126250, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32234618

RESUMO

Presence of even small amount of active pharmaceutical ingredients in the environment carries risks to human and animal health, presenting an important issue. The paper presents issues related to the new drug - pimavanserin (PMV). Biological treatment efficiency of pimavanserin (PMV) was evaluated using lab-scale Sequencing Batch Reactor (SBR). It has been shown to have a negative effect on aquatic organisms by classifying it as a toxic compound (EC50 = 8 mgL-1). The level of biological degradation of PMV was insufficient (37%) and intensively foam formation caused operational problems. For this reason, in this study polymers based on cyclodextrins (CDs) were synthesized and used as adsorbents alternative to active carbons to effectively separate PMV from real industrial waste streams. Crosslinked ß- and γ-CD polymers (ß- and γ-NS), obtained in reaction with 1,1'-carbonyldiimidazole (CDI), were fully characterized by physicochemical methods. The adsorption equilibrium data were interpreted using Freundlich and Langmuir models. The sorption process was fast (60 s) and the efficiency of PMV separation from model waste waters was 93% and 81% for ß- and γ-NS, respectively. Maximum polymer capacity was found at 52.08 mg g-1 for ß-NS and 23.26 mg g-1 for γ-NS. The interactions of PMV with CDs have been studied and indicate that major mechanism of the sorption is based on supramolecular interaction and capture to polymer network. Described biodegradable and reusable materials are perfect example of correctly selected adsorbent for separation of target substance from postproduction aqueous media.


Assuntos
Piperidinas/química , Ureia/análogos & derivados , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/química , Adsorção , Celulose/química , Ciclodextrinas/química , Resíduos Industriais , Preparações Farmacêuticas , Polímeros/química , Ureia/química , Águas Residuárias , beta-Ciclodextrinas/química
11.
Food Chem ; 321: 126750, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32278273

RESUMO

This work investigated the interaction between cyclodextrins and pullulanase to provide insight into the production and application of cyclodextrins. Enzyme activity and kinetic assays showed that α-cyclodextrin (α-CD), ß-cyclodextrin (ß-CD) and γ-cyclodextrin (γ-CD) inhibited pullulanase in a competitive manner. Circular dichroism spectra and fluorescence spectroscopy suggested the formation of cyclodextrin and pullulanase complexes. According to ITC assays and molecular docking results, compared with α-CD and γ-CD, ß-CD had the strongest affinity for pullulanase because of its appropriate cavity geometric dimensions. In addition, cyclodextrins interacted with pullulanase through hydrogen bonds, van der Waals force and hydrophobic interactions, the latter of which were verified as the major driving force. Phenylalanine 476 was the key amino acid residue in pullulanase for cyclodextrin recognition and binding.


Assuntos
Ciclodextrinas/química , Ciclodextrinas/metabolismo , Glicosídeo Hidrolases/química , Glicosídeo Hidrolases/metabolismo , Calorimetria/métodos , Dicroísmo Circular , Glicosídeo Hidrolases/antagonistas & inibidores , Ligação de Hidrogênio , Simulação de Acoplamento Molecular , Fenilalanina/metabolismo , Estrutura Secundária de Proteína , Espectrometria de Fluorescência , alfa-Ciclodextrinas/química , alfa-Ciclodextrinas/metabolismo , beta-Ciclodextrinas/química , beta-Ciclodextrinas/metabolismo , gama-Ciclodextrinas/química , gama-Ciclodextrinas/metabolismo
12.
Sci China Life Sci ; 63(8): 1142-1158, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32253589

RESUMO

Proteins are one of the major classes of biomolecules that execute biological functions for maintenance of life. Various kinds of nanostructures self-assembled from proteins have been created in nature over millions of years of evolution, including protein nanowires, layers and nanocages. These protein nanostructures can be reconstructed and equipped with desired new functions. Learning from and manipulating the self-assembly of protein nanostructures not only help to deepen our understanding of the nature of life but also offer new routes to fabricate novel nanomaterials for diverse applications. This review summarizes the recent research progress in this field, focusing on the characteristics, functionalization strategies, and applications of protein nanostructures.


Assuntos
Nanoestruturas/química , Proteínas/química , Animais , Técnicas Biossensoriais/métodos , Catálise , Simulação por Computador , Ciclodextrinas/química , Humanos , Peptídeos/química , Conformação Proteica , Multimerização Proteica , Proteínas Recombinantes/química , Relação Estrutura-Atividade , Propriedades de Superfície , Vírus/química
13.
Langmuir ; 36(16): 4317-4323, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32271592

RESUMO

We present self-assembled Pickering emulsions containing biocidal phytochemical oils (carvacrol and terpinen-4-ol) and ß-cyclodextrin able to potentiate the antimicrobial and antibiofilm activity of miconazoctylium bromide. The carvacrol-containing emulsion is 2-fold more sensitive against C. albicans and S. aureus and highly active against E. coli, compared to the commercial cream containing miconazole nitrate. Moreover, this emulsion shows a synergistic effect against fungi, additive responses against bacteria, and remarkable staphylococcal biofilm eradication. These results are associated with membrane permeabilization, enzymes inhibition, and the accumulation of reactive oxygen species in microorganisms.


Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Biofilmes/efeitos dos fármacos , Ciclodextrinas/química , Emulsões/química , Candida albicans/efeitos dos fármacos , Cimenos/farmacologia , Escherichia coli/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/fisiologia , Terpenos/farmacologia
14.
Nanotechnology ; 31(25): 255101, 2020 Apr 03.
Artigo em Inglês | MEDLINE | ID: mdl-32143196

RESUMO

Drug delivery carriers hold tremendous promise for improving cancer treatment, and polyrotaxane (PR) has shown excellent drug-carrying properties. However, there have been some reports that, when used as a drug carrier, water-soluble PR is not easily labeled with organic fluorescent dyes. Herein, we synthesized a drug-loaded fluorescent porphyrin-terminated PR (PR-COOH) which can be used as a tracer material in drug and gene delivery. The structure, morphology and zeta potential of PR-COOH were characterized by nuclear magnetic resonance, high-resolution transmission electron microscopy and zeta potentiometry. In this research, cisplatin (CDDP) is used as a model drug. The zeta potential, drug encapsulation efficiency and drug release of CDDP-loaded PR (PR-COOH-Pt) were studied. Confocal laser scanning microscopy showed that PR-COOH could be internalized by HeLa and CT26 cells. The antitumor efficacy of PR-COOH-Pt was investigated in vitro by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and in vivo by a xenograft tumor model. The results showed that PR-COOH-Pt could significantly inhibit tumor growth; thus PR-COOH-Pt has a promising role in cancer therapy.


Assuntos
Antineoplásicos/administração & dosagem , Cisplatino/administração & dosagem , Ciclodextrinas/síntese química , Neoplasias Hepáticas/tratamento farmacológico , Poloxâmero/síntese química , Porfirinas/química , Rotaxanos/síntese química , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Cisplatino/química , Cisplatino/farmacologia , Ciclodextrinas/química , Portadores de Fármacos/química , Liberação Controlada de Fármacos , Células HeLa , Humanos , Espectroscopia de Ressonância Magnética , Camundongos , Nanopartículas , Poloxâmero/química , Rotaxanos/química , Ensaios Antitumorais Modelo de Xenoenxerto
15.
Soft Matter ; 16(13): 3311-3318, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-32175550

RESUMO

Herein, we describe the synthesis of poly(1,8-octamethylene citrate) materials modified in the bulk with 2-hydroxypropyl-ß-cyclodextrin (cPOCCD), biodegradable elastomers with intrinsic sorption properties for drug delivery. The chemical structure, physicochemical properties, in vitro drug loading and release profiles of cPOCCD were investigated. Thus, cPOCCD polyesters absorb the studied drugs more effective and release them for a longer period of time than poly(1,8-octamethylene citrate) materials not containing cyclodextrins.


Assuntos
Ciclodextrinas/química , Sistemas de Liberação de Medicamentos , Elastômeros/química , beta-Ciclodextrinas/química , 2-Hidroxipropil-beta-Ciclodextrina/química , Citratos/química , Ciclodextrinas/síntese química , Elastômeros/síntese química , Humanos , Tamanho da Partícula , Poliésteres/química , Polímeros/química
16.
Chemosphere ; 250: 126226, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32088621

RESUMO

A novel catalyst which integrates heterogeneous and homogenous Fenton reactions is designed and fabricated by encapsulating 2,5-dihydroxy-1,4-benzoquinone (2,5-DBQ) in ECDP-Fe3O4, a composite of Fe3O4 nanoparticles immobilized on a ß-cyclodextrin polymer (ECDP) with ethylene diamine tetraacetic acid (EDTA) as cross-linking agent. The 2,5-DBQ@ECDP-Fe3O4 has superior catalytic performance for 4-nitrophenol and 2,4-dichlorophenol degradation compared with control systems. Mechanism study revealed that although the initial active site is Fe3O4 loaded on ECDP, the actually catalyst is the iron ions released from Fe3O4 but confined within the composite. EDTA in ß-cyclodextrin polymer can improve both the solubility and adsorption capacity to H2O2 of Fe3O4. The quinone molecules 2,5-DBQ in the ß-cyclodextrin cavity can accelerate Fe3+/Fe2+ cycle adjacent to the cavity, thus in favor of the decomposition of H2O2 into OH as main reactive oxidizing species. The current catalyst integrates the advantages of homogeneous and heterogeneous advanced oxidation processes and is promising in practical applications.


Assuntos
Celulose/química , Ciclodextrinas/química , Ferro/química , Modelos Químicos , Adsorção , Catálise , Ácido Edético , Peróxido de Hidrogênio/química , Oxirredução
17.
Carbohydr Res ; 489: 107954, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32087382

RESUMO

The Suzuki reaction is one of the most effective methods for the formation of carbon-carbon bonds and is of great utility in organic synthesis. Recently, cyclodextrin based palladium catalysts were found to be very selective, convenient and efficient for Suzuki cross-coupling reactions. This review focuses on such cyclodextrin systems of palladium which act as efficient catalysts with high catalytic activity and recyclability in Suzuki reaction and covers literature up to 2019.


Assuntos
Técnicas de Química Sintética , Complexos de Coordenação/química , Ciclodextrinas/química , Paládio/química , Catálise , Ligantes , Estrutura Molecular
18.
Food Chem ; 317: 126328, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32087520

RESUMO

In this study, cyclodextrin metal-organic framework/chitosan (CD-MOF/CS) nanocapsules, which have a hydrophobic core and a hydrophilic shell, were fabricated as delivery systems for bioactive agents. The nanocapsules were prepared by electrostatic deposition of cationic chitosan onto the anionic CD-MOF core. The presence of the CS coating reduced the mean diameter and polydispersity index of the nanocapsules, which was attributed to their ability to inhibit particle aggregation. Moreover, the encapsulation efficiency of resveratrol within the nanocapsules increased appreciably after coating them with chitosan (from 66.5 to 91.3%). The chitosan coating was also shown to increase the antioxidant activity and photostability of the encapsulated resveratrol. Information about the binding interactions of the resveratrol with the nanocapsules was obtained using fluorescence spectroscopy, infrared spectroscopy, and thermal analysis. The new nanocapsules created in this study may have applications for the encapsulation, protection, and delivery of bioactive agents in food, supplement, and pharmaceutical applications.


Assuntos
Ciclodextrinas/química , Portadores de Fármacos/química , Estruturas Metalorgânicas/química , Nanocápsulas/química , Resveratrol/química , Quitosana/química , Géis/química , Interações Hidrofóbicas e Hidrofílicas , Tamanho da Partícula , Termogravimetria
19.
Sci Adv ; 6(5): eaax9318, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32064341

RESUMO

Viral infections kill millions of people and new antivirals are needed. Nontoxic drugs that irreversibly inhibit viruses (virucidal) are postulated to be ideal. Unfortunately, all virucidal molecules described to date are cytotoxic. We recently developed nontoxic, broad-spectrum virucidal gold nanoparticles. Here, we develop further the concept and describe cyclodextrins, modified with mercaptoundecane sulfonic acids, to mimic heparan sulfates and to provide the key nontoxic virucidal action. We show that the resulting macromolecules are broad-spectrum, biocompatible, and virucidal at micromolar concentrations in vitro against many viruses [including herpes simplex virus (HSV), respiratory syncytial virus (RSV), dengue virus, and Zika virus]. They are effective ex vivo against both laboratory and clinical strains of RSV and HSV-2 in respiratory and vaginal tissue culture models, respectively. Additionally, they are effective when administrated in mice before intravaginal HSV-2 inoculation. Lastly, they pass a mutation resistance test that the currently available anti-HSV drug (acyclovir) fails.


Assuntos
Ciclodextrinas/farmacologia , Herpesvirus Humano 1/efeitos dos fármacos , Herpesvirus Humano 2/efeitos dos fármacos , Viroses/tratamento farmacológico , Aciclovir/química , Aciclovir/farmacologia , Animais , Antivirais/síntese química , Antivirais/química , Antivirais/farmacologia , Ciclodextrinas/síntese química , Ciclodextrinas/química , Feminino , Ouro/química , Heparitina Sulfato/química , Heparitina Sulfato/farmacologia , Herpesvirus Humano 1/patogenicidade , Herpesvirus Humano 2/patogenicidade , Humanos , Nanopartículas Metálicas/química , Camundongos , Simplexvirus/efeitos dos fármacos , Simplexvirus/patogenicidade , Viroses/virologia , Zika virus/efeitos dos fármacos , Zika virus/patogenicidade
20.
Molecules ; 25(2)2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31936059

RESUMO

In attempt to broaden the use of cyclodextrin polymer for catalytic purposes, a novel covalent hybrid system was prepared through growth of multi-nitrogen atom containing polymer (PMelamine) derived from reaction of ethylenediamine and 2,4,6-trichloro-1,3,5-triazine on the functionalized cyclodextrin polymer (CDNS). The resulting hybrid system was then utilized as a catalyst support for the immobilization of silver nanoparticles through using Cuscuta epithymum extract as a naturally-derived reducing agent. The catalytic activity of the catalyst, Ag@CDNS-N/PMelamine, for the synthesis of xanthenes through reaction of aldehydes and dimedone in aqueous media was examined. The results showed high catalytic activity and recyclability of the catalyst. It was believed that cyclodextrin in the backbone of the catalyst could act both as a capping agent for Ag nanoparticles and phase transfer agent to bring the hydrophobic substrates in the vicinity of the catalytic active sites and accelerate the reaction rate. Multi-nitrogen atoms on the polymer, on the other hand, could improve the Ag NPs anchoring and suppress their leaching.


Assuntos
Celulose/química , Ciclodextrinas/química , Nanopartículas Metálicas/química , Nitrogênio/química , Prata/química , Xantenos/síntese química , Catálise , Cuscuta/química , Nanopartículas Metálicas/ultraestrutura , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Polímeros/síntese química , Polímeros/química , Triazinas/química , Xantenos/química
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA