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1.
Artigo em Inglês | MEDLINE | ID: mdl-31704622

RESUMO

Puerariae Radix (PR) serves as food and medicinal plant for thousands of years with explicit efficacy for heart diseases, while biological target specifically binding-oriented screening of the active components in PR remains a preliminary stage. Cell membrane chromatography (CMC) is newly developed approach where interactions between active components and certain biological targets can be effectively studied, Human umbilical vein endothelial cell (HUVEC) membrane, with its abundant receptors such as ß and AT1, is most eligible for constructing CMC. In this study, an HUVEC/CMC-LC-MS2 system was developed for screening active components in PR, 11 compounds were screened out and four of them were identified. Besides puerarin, the rest identified are daidzin, pueroside D and 3'-hydroxypuerarin. The study provides more reference for CMC applications and PR exploitation.


Assuntos
Membrana Celular/metabolismo , Cromatografia de Afinidade/métodos , Medicamentos de Ervas Chinesas/análise , Isoflavonas/análise , Espectrometria de Massas/métodos , Linhagem Celular , Medicamentos de Ervas Chinesas/química , Medicamentos de Ervas Chinesas/metabolismo , Células Endoteliais da Veia Umbilical Humana , Humanos , Isoflavonas/química , Isoflavonas/isolamento & purificação , Isoflavonas/metabolismo , Reprodutibilidade dos Testes
2.
Anal Chim Acta ; 1088: 63-71, 2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31623717

RESUMO

Magnetic nanoparticles (MNPs) have been widely explored in enrichment of low-abundance glycoproteins/glycopeptides prior to mass spectrometry analysis in glycoproteomics. Currently, most functional groups for recognizing glycoproteins/glycopeptides are usually immobilized on the nanomaterial surface based on covalent modification, which suffers from multistep treatment, surface-dependence, and harsh conditions. In this work, we first report a facile and rapid method for surface functionalization and subsequent glycopeptides enrichment via one-step assembly of maltose-modified oligopeptides with a sequence of Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys (AEK8-maltose). In physiological conditions, AEK8-maltose readily self-organized into a complete coating layer dominated by ß-sheets on the surface of SiO2@Fe3O4 and C@Fe3O4 MNPs, which remain intact to repeat washing with acidic organic and aqueous solutions extensively used in the sample enrichment treatments. Thus, the resulting AEK8-maltose functionalized MNPs show excellent performance in enrichment of glycopeptides in standard glycoprotein digests (24 glycopeptides from horseradish peroxidase (HRP), 31 glycopeptides from immunoglobulin (IgG)) and human serum digests (282 glycopeptides), including rapid enrichment speed (5 min), high detection sensitivity (0.001 ng/µL HRP), high selectivity (mass ratios of HRP and bovine serum albumin (BSA) digests up to 1:150), good enrichment recovery (over 86.3%), remarkable stability (repeatable for more than 8 times), and excellent renewability, which are better than or comparable with the literature results reported to date. The current work based on self-assembling oligopeptides provides a mild, economic and nontoxic procedure for one-step surface functionalization of various nanomaterials.

3.
Mikrochim Acta ; 186(5): 307, 2019 04 27.
Artigo em Inglês | MEDLINE | ID: mdl-31030307

RESUMO

A ratiometric fluorometric assay for mercury(II) ion is described. It is making use of glutathione-stabilized gold nanoclusters (GSH-AuNCs) modified with tetraphenylporphyrin tetrasulfonic acid (TPPS). The resultant GSH-AuNC/TPPS nanocomposite displays dual emission (at 572 and 664 nm) under a single excitation wavelength of 365 nm. Mercury(II) ion intensively quenches the yellow fluorescence of GSH-AuNCs (peaking at 572 nm) but has a negligible effect on the red fluorescence of TPPS (at 664 nm). The ratio of fluorescence intensities at 572 and 664 nm drops linearly with Hg(II) ion concentration in the 0.02-2.0 µmol·L-1 range, and the detection limit is 7 nmol·L-1 (3sb/S). The relative standard deviation (RSD) of the assay is 2.0% at a 0.5 µmol·L-1 concentration level (n = 11). The method was successfully applied to the determination of Hg(II) ion in spiked water samples, with recoveries within the range of 87.5-107.5%. Graphical abstract Ratiometric fluorescence detection of mercury(II).

4.
J Food Drug Anal ; 25(2): 327-332, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28911674

RESUMO

Essential oils from the seed, pulp, and leaf of sea buckthorn were obtained with hydrodistillation, and their phytochemical composition was analyzed through gas chromatography-mass spectrometry. Furthermore, the antibacterial activity of the oils was tested on five food-borne bacteria by spectrometry and evaluated in terms of minimum inhibitory concentration. The results indicate that the composition of all essential oils is dominated by free fatty acids, esters, and alkanes. Minimum inhibitory concentration values on each bacterium were obtained for oils from different parts. The oils from different parts exhibited nearly equal inhibitory effect on Staphylococcus aureus. The pulp oil was found to be the most effective for the rest of bacteria tested except Escherichia coli, on which seed oil shows twice the inhibitory effect to that of leaf or pulp oil. Three natural inhibitory examples were found comparable with or even better than the positive control: pulp oil on Bacillus subtilis, and pulp oil and leaf oil on Bacillus coagulans.


Assuntos
Hippophae , Antibacterianos , Bactérias , Cromatografia Gasosa-Espectrometria de Massas , Testes de Sensibilidade Microbiana , Óleos Voláteis , Compostos Fitoquímicos , Sementes , Staphylococcus aureus
5.
Artigo em Inglês | MEDLINE | ID: mdl-28578848

RESUMO

Vonoprazan Fumarate (TAK-438F) is a new and effective drug approved in Japan in 2014 for treatment and prevention of acid-related diseases (ARDs), which exhibits many advantages compared with traditional proton-pump inhibitors (PPIs). However, the clinical applications of TAK0-438F suffers limitation due to the lack of injection dosage form. Efforts to overcome this limitation lead to the systhesis of Vonoprazan pyroglutamate (TAK-438P) for its high water solubility and more potent antisecretory effect. This was the first report to establish and validate a reliable and sensitive LC-MS/MS method for the quantification of TAK-438P in rat plasma and tissues (heart, liver, spleen, liver, kidney, rain, stomach and small intestine). All the features of the developed method suggested it was within bioanalytical criteria recommended by regulatory authorities. Furthermore, the developed method was applied to the exploration of the bioequivalence between TAK-438P and TAK-438F, as well as the pharmacokinetics and tissue distribution of TAK-438P. The results showed that there was no significant differences between TAK-438P and TAK-438F after oral administration of the same dose. Besides, TAK-438P was rapidly absorbed and eliminated in rat plasma. And it was widely distributed and there was no long-term accumulation in most tissues. Notably, more than 2000ng/mL was observed in stomach 12h after oral administration. The high accumulation revealed that stomach was likely to be the target organs of TAK-438P.


Assuntos
Pirróis/farmacocinética , Sulfonamidas/farmacocinética , Administração Oral , Animais , Cromatografia Líquida de Alta Pressão , Estabilidade de Medicamentos , Japão , Masculino , Pirróis/administração & dosagem , Pirróis/sangue , Ratos , Ratos Sprague-Dawley , Reprodutibilidade dos Testes , Estômago , Sulfonamidas/administração & dosagem , Sulfonamidas/sangue , Espectrometria de Massas em Tandem , Equivalência Terapêutica , Distribuição Tecidual
6.
Chem Commun (Camb) ; 51(38): 8078-81, 2015 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-25869672

RESUMO

We propose a visual volumetric sensor with 5,6-dicarboxylic fluorescein cross-linked amine-functionalized polyacrylamide hydrogel. The sensor undergoes volume response to Cu(2+) ions at the µM level, which enables naked-eye quantitative detection by reading the graduation on a pipette.

7.
J Am Soc Mass Spectrom ; 25(8): 1322-31, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24839193

RESUMO

The mechanisms whereby protein ions are liberated from charged droplets during electrospray ionization (ESI) remain under investigation. Compact conformers electrosprayed from aqueous solution in positive ion mode likely follow the charged residue model (CRM), which envisions analyte release after solvent evaporation to dryness. The concentration of nonvolatile salts such as NaCl increases sharply within vanishing CRM droplets, promoting nonspecific pairing of Cl(-) and Na(+) with charged groups on the protein surface. For unfolded proteins, it has been proposed that ion formation occurs via the chain ejection model (CEM). During the CEM proteins are expelled from the droplet long before complete solvent evaporation has taken place. Here we examine whether salt adduction levels support the view that folded and unfolded proteins follow different ESI mechanisms. Solvent evaporation during the CEM is expected to be less extensive and, hence, the salt concentration at the point of protein release should be substantially lower than for the CRM. CEM ions should therefore exhibit lower adduction levels than CRM species. We explore the adduction behavior of several proteins that were chosen to allow comparative studies on folded and unfolded structures in the same solution. In-source activation eliminates chloride adducts via HCl release, generating protein ions that are heterogeneously charged because of sodiation and protonation. Sodiation levels measured under such conditions provide estimates of the salt adduction behavior experienced by the "nascent" analyte ions. Sodiation levels are significantly reduced for unfolded proteins, supporting the view that these species are indeed formed via the CEM.


Assuntos
Citocromos c/química , Indicadores e Reagentes/química , Modelos Moleculares , Muramidase/química , Mioglobina/química , Cloreto de Sódio/química , Animais , Apoproteínas/química , Galinhas , Cavalos , Concentração de Íons de Hidrogênio , Cloreto de Potássio/química , Desdobramento de Proteína , Espectrometria de Massas por Ionização por Electrospray
8.
Anal Chem ; 85(13): 6469-76, 2013 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-23724896

RESUMO

Many protein investigations by electrospray ionization (ESI) mass spectrometry (MS) strive to ensure a "native" solvent environment, i.e., nondenaturing conditions up to the point of gas-phase ion formation. Ideally, these studies would employ a volatile pH buffer to mitigate changes in H(+) concentration that can occur during ESI. Ammonium acetate is a commonly used additive, despite its low buffering capacity at pH 7. Ammonium bicarbonate provides greatly improved pH stabilization, thus offering an interesting alternative. Surprisingly, protein analyses in bicarbonate at pH 7 tend to result in the formation of very high charge states, similar to those obtained when electrospraying unfolded proteins in a denaturing solvent. This effect has been reported previously (Sterling, H. J.; Cassou, C. A.; Susa, A. C.; Williams, E. R. Anal. Chem. 2012, 84, 3795), but its exact mechanistic origin remains unclear. ESI-mediated unfolding does not take place in acetate under otherwise identical conditions. We demonstrate that heating of protein-containing bicarbonate solutions results in extensive foaming, caused by CO2 outgassing. In contrast, acetate solutions do not generate foam. Protein denaturation caused by gas bubbles is a well-known phenomenon. Adsorption to the gas/liquid interface is accompanied by major conformational changes that allow the protein to act as a surfactant. The foaming of beer is a manifestation of this effect. Bubble formation in bicarbonate during ESI is facilitated by collisional and blackbody droplet heating. Our data imply that heat and bubbles act synergistically to cause unfolding during the electrospray process, while proteins reside in ESI droplets. Because of this effect we advise against the use of ammonium bicarbonate for native ESI-MS. Ammonium acetate represents a gentler droplet environment, despite its low buffering capacity.


Assuntos
Bicarbonatos/química , Gases/química , Mioglobina/análise , Desdobramento de Proteína , Espectrometria de Massas por Ionização por Electrospray/métodos , Animais , Bicarbonatos/toxicidade , Gases/toxicidade , Cavalos , Mioglobina/química , Desdobramento de Proteína/efeitos dos fármacos
9.
J Chromatogr Sci ; 51(2): 122-7, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22776738

RESUMO

A type of weak cation exchanger was prepared based on poly(glycidylmethacrylate-co-ethylenedimethacrylate). The effects of pH and ionic strength on the adsorption behavior were studied, and the results suggested that the adsorption of lysozyme onto a weak cation exchanger is electrostatic interaction, and that the adsorption behavior is in accordance with the Langmuir adsorption model with a correlation coefficient greater than 0.99. It was also found that increasing ionic strength led to a decrease of the adsorption of lysozyme from 49.50 to 28.09 mg/g. Preliminary chromatographic experiments were conducted to test the separation properties of the weak cation exchanger, and the results demonstrated that the retention time of different proteins could be predicted in order of their isoelectric point.


Assuntos
Cromatografia por Troca Iônica/métodos , Metacrilatos/química , Muramidase/química , Poliestirenos/química , Adsorção , Animais , Cátions/química , Galinhas , Cromatografia por Troca Iônica/instrumentação , Concentração de Íons de Hidrogênio , Ponto Isoelétrico , Microesferas , Muramidase/análise , Muramidase/farmacocinética , Concentração Osmolar , Análise de Regressão
10.
Biosens Bioelectron ; 41: 137-42, 2013 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-22954528

RESUMO

Specific and homogeneous detection of heavy metal ion is of great importance for both human health care and environmental protection. We reported a highly specific and sensitive assay for fluorescent detection of Pb(2+) based on the difference in quenching ability between deoxyguanosines and G-quartet by using carboxyfluorescein-labeled hairpin DNA (F-hpDNA) as a recognition probe. In the absence of target, the fluorescence of F-hpDNA can be quenched through photoinduced electron transfer from the dye to deoxyguanosines because the formation of hairpin brings deoxyguanosines close to the FAM. In the presence of Pb(2+), the formation of G-quadruplex DNA leads to a significant decrease in fluorescence due to the effective stack of dye on the G-quartet, which obviously intensified the quenching of fluorophore. In comparison with linear DNA probe, hairpin DNA probe greatly improved the specificity, and Pb(2+) can be highly selective detected even when coexisted with other metal ions. The quenching efficiency is linear with the concentration of lead(II) over the range of 0.5-500 nM, with a limit of detection of 0.4 nM. Conformational switch from hairpin to G-quadruplex was verified by CD measurements. Moreover, the application for detection of real samples further demonstrated its reliability. Therefore, it is a selective, simple and sensitive approach for detection of lead ion, as such, it promises to provide a solid foundation for developing universal analytical method for heavy metal ions.


Assuntos
Técnicas Biossensoriais/instrumentação , Desoxiguanosina/química , Quadruplex G , Chumbo/análise , Espectrometria de Fluorescência/instrumentação , Poluentes Químicos da Água/análise , Desoxiguanosina/genética , Monitoramento Ambiental/métodos , Desenho de Equipamento , Análise de Falha de Equipamento , Sequências Repetidas Invertidas , Microquímica/instrumentação , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
11.
J Chromatogr Sci ; 44(9): 574-8, 2006 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-17059686

RESUMO

A new bioactive packing material for liquid chromatography, sarcolemma chromatography stationary phase (SCSP), is presented. Its surface characteristics are investigated, and it is found that the acceptors embedded in sarcolemma remained bioactive for more than a week. The retention behavior of antagonists and activators related to cardiac muscle sarcolemma on the SCSP chromatographic column shows the screening function of the SCSP column, and the retention behavior of the active components in the aether extract from the Chinese herb Ligusticum chuanxiong Hort. on the SCSP column reveals, to a certain extent, the separation function of the SCSP column. These suggest that SCSP is a potentially useful material in drug screening.


Assuntos
Miocárdio/química , Preparações Farmacêuticas/isolamento & purificação , Sarcolema/química , Ligusticum/química , Microscopia Eletrônica de Varredura , Extratos Vegetais/análise
12.
Zhongguo Zhong Yao Za Zhi ; 30(2): 129-33, 2005 Jan.
Artigo em Chinês | MEDLINE | ID: mdl-15714818

RESUMO

OBJECTIVE: To study the interactions between Ligusticum chuanxiong Hort extract and cardiac muscle membrane receptors. METHOD: The cell membrane of rabbit cardiac muscle was fixed on silicon to make cell membrane stationary phase (CMSP), and then the interactions were studied by comparing the retention characteristics of the extracts from different solvents with those of the antagonists or activators corresponding to known receptors in cardiac muscle membrane, and by competition effect on the retention characteristics of extracts when adding the antagonists or activators into the mobile phase. RESULT: Water extract and ethanol extract both had retentions on CMSP; the retention characteristics of water extract could be affected when water extract was in competition with the antagonists for alpha receptor, and could not be affected when with the activator beta1 receptor. CONCLUSION: It is possible that some components in water extract may combine with alpha receptor and no component with beta1 receptor, and that some components in ethanol extract may combine with cardiac muscle cell membrane. The process between active components and receptors in vivo can be imitated through the interactions between drugs and CMSP. The method provides references for the resolution of two applications: to screen the active components from Chinese medicine, and to figure out the type of receptors involved.


Assuntos
Medicamentos de Ervas Chinesas/farmacologia , Ligusticum/química , Miócitos Cardíacos/metabolismo , Plantas Medicinais/química , Receptores Adrenérgicos alfa/metabolismo , Agonistas alfa-Adrenérgicos/metabolismo , Antagonistas Adrenérgicos alfa/metabolismo , Agonistas Adrenérgicos beta/metabolismo , Antagonistas Adrenérgicos beta/metabolismo , Animais , Membrana Celular/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Medicamentos de Ervas Chinesas/isolamento & purificação , Feminino , Masculino , Miócitos Cardíacos/citologia , Ligação Proteica , Coelhos , Receptores Adrenérgicos beta/metabolismo
13.
Zhongguo Zhong Yao Za Zhi ; 29(7): 660-2, 2004 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-15503774

RESUMO

OBJECTIVE: To study the interactions between four components in Ligusticum chuanxiong rhizome and heart cell membrane acceptors. METHOD: Through observing the retention characteristics of the four components (tetramethylpyrazine, vanillic, chrysophol, ferulic acid) on cell membrane stationary phase (CMSP) chromatographic column, whether the components combine with cell membrane acceptors was studied, and through further comparing the retention characteristics with those of known activators or antagonists corresponding to cell membrane acceptors, the kind of acceptor with which one component combines was studied. RESULT: Tetramethylpyrazine, vanillic and chrysophol had retention on CMSP chromatographic column while ferulic acid hadn't. The retention characteristics of tetramethylpyrazine were similar to activator and antagonist corresponding to a acceptor, vanillic with beta1 acceptor activator. CONCLUSION: Tetramethylpyrazine, vanillic and chrysophol can all combine with cardiac muscle membrane acceptors, while ferulic acid can not; tetramethylpyrazine probably acts on a acceptor and vanillic acts on beta1 acceptor.


Assuntos
Ligusticum/química , Miócitos Cardíacos/metabolismo , Pirazinas/metabolismo , Receptores Adrenérgicos alfa/metabolismo , Ácido Vanílico/metabolismo , Animais , Antraquinonas/isolamento & purificação , Antraquinonas/metabolismo , Membrana Celular/metabolismo , Ácidos Cumáricos/isolamento & purificação , Ácidos Cumáricos/metabolismo , Feminino , Masculino , Miócitos Cardíacos/citologia , Plantas Medicinais/química , Ligação Proteica , Pirazinas/isolamento & purificação , Coelhos , Receptores Adrenérgicos beta/metabolismo , Rizoma/química , Ácido Vanílico/isolamento & purificação
14.
Talanta ; 62(1): 97-101, 2004 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-18969269

RESUMO

A new flow injection catalytic spectrophotometric method is proposed for the simultaneous determination of nitrite and nitrate based on the catalytic effect of nitrite on the redox reaction between crystal violet and potassium bromate in phosphoric acid medium and nitrate being on-line reduced to nitrite with a cadmium-coated zinc reduction column. The redox reaction is monitored spectrophotometrically by measuring the decrease in the absorbance of crystal violet at the maximum absorption wavelength of 610nm. A technique of inserting a reduction column into sampling loop is adopted and the flow injection system produces a signal with a shoulder. The height of shoulder in the ascending part of the peak corresponds to the nitrite concentration and the maximum of the peak corresponds to nitrate plus nitrite. The detection limits are 0.3ngml(-1) for nitrite and 1.0ngml(-1) for the nitrate. Up to 32 samples can be analyzed per hour with a relative standard deviation of less than 2%. The method has been successfully applied for the simultaneous determination of nitrite and nitrate in natural waters.

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