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排序方式: 共有149条查询结果,搜索用时 15 毫秒
1.
Theophylline(1,3-dimethylxanthine), dyphylline [7-(2,3-dihydroxypropyl)theophylline] and proxyphylline [7-(beta-hydroxypropyl)theophylline] are three bronchodilators administered jointly in a single pharmaceutical preparation used against asthma. A micellar electrokinetic chromatography (MEKC) method for their resolution using a background electrolyte consisting of 20 mM tetraborate at pH 8.5 and 100 mM sodium dodecyl sulfate is proposed. The method was used to determine the three active principles in a pharmaceutical preparation. The small amount of sample required and the expeditiousness of the procedure allow content uniformity to be determined in individual tablets. The values of the validation parameters for the method (viz. selectivity, linearity, accuracy, precision, limit of detection, limit of quantitation and robustness) are reported. A complete factor design (2(3)x2) including pH, the surfactant concentration and the ionic strength of the background electrolyte as factors was used to estimate robustness. Based on the results, the method is robust enough for quantitation purposes. 相似文献
2.
Ana M. Gómez Ana PedregosaSeraf?&#x;n Valverde J.Cristóbal López 《Tetrahedron letters》2003,44(32):6111-6116
Halo-exo-glycals of the gluco-, manno- and galacto- series, readily prepared by reaction of 1-exo-methylene pyranoses with iodonium dicollidinium triflate (IDCT), undergo Suzuki or B-alkyl Suzuki cross-coupling reactions with boronic acids or alkyl boranes to yield, in a stereoselective manner, functionalized exo-glycals. 相似文献
3.
An anionic sensor based on Reichardt’s betaine is described here. The dye is blue-green in chloroform but becomes colorless under protonation. Increasing amounts of different anions were added into the solution of the protonated dye. The addition of F− and caused the reappearance of the original blue-green color, while the addition of I− made the solution of the protonated dye yellow. The observations are discussed based on the fact that F− and can act as bases accepting a proton from the protonated dye and also in relation to the formation of a complex between the protonated dye and iodide. 相似文献
4.
Ana M. Gómez Aitor Barrio Serafín Valverde J. Cristóbal López 《Tetrahedron letters》2006,47(35):6243-6246
(Z)-exo-Glycals can be conveniently prepared in a convergent manner by Stille cross-coupling of (Z)-halo(Br,I)-exo-glycals and aryl or alkenyl stannanes, the latter are readily obtained by addition of tributylstannyl radicals to terminal alkynes. 相似文献
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Apoorva D. Srivastava Dr. Luca Unione Dr. Margreet A. Wolfert Dr. Pablo Valverde Dr. Ana Ardá Prof. Dr. Jesús Jiménez-Barbero Prof. Dr. Geert-Jan Boons 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(67):15605-15612
The parasitic worm, Schistosoma mansoni, expresses unusual fucosylated glycans in a stage-dependent manner that can be recognized by the human innate immune receptor DC-SIGN, thereby shaping host immune responses. We have developed a synthetic approach for mono- and bis-fucosylated LacdiNAc (LDN-F and LDN-DF, respectively), which are epitopes expressed on glycolipids and glycoproteins of S. mansoni. It is based on the use of monosaccharide building blocks having carefully selected amino-protecting groups, facilitating high yielding and stereoselective glycosylations. The molecular interaction between the synthetic glycans and DC-SIGN was studied by NMR and molecular modeling, which demonstrated that the α1,3-fucoside of LDN-F can coordinate with the Ca2+-ion of the canonical binding site of DC-SIGN allowing for additional interactions with the underlying LDN backbone. The 1,2-fucoside of LDN-DF can be complexed in a similar manner, however, in this binding mode GlcNAc and GalNAc of the LDN backbone are placed away from the protein surface resulting in a substantially lower binding affinity. Glycan microarray binding studies showed that the avidity and selectivity of binding is greatly enhanced when the glycans are presented multivalently, and in this format Lex and LDN-F gave strong responsiveness, whereas no binding was detected for LDN-DF. The data indicates that S. mansoni has developed a strategy to avoid detection by DC-SIGN in a stage-dependent manner by the addition of a fucoside to a number of its ligands. 相似文献
10.
Alejandro Valverde Amira ben Hassine Vernica Serafín Cristina Muoz‐San Martín María Pedrero María Garranzo‐Asensio Maria Gamella Noureddine Raouafi Rodrigo Barderas Paloma Yez‐Sedeo Susana Campuzano Jos M. Pingarrn 《Electroanalysis》2020,32(4):706-714
This paper reports the development of a dual immunosensor using magnetic microcarriers (MBs) and amperometric transduction at dual screen‐printed carbon electrodes (SPdCEs) for the simultaneous determination of two biomarkers: interleukin‐13 receptor α2 (IL‐13Rα2) and E‐cadherin (E‐CDH), with both extracellular and soluble fraction; oncogenic and tumor suppressor markers, respectively, of great relevance in metastatic processes. The implemented methodology involved the formation of sandwich‐type immunocomplexes using specific capture antibodies immobilized onto carboxylic acid magnetic microbeads (HOOC‐MBs), and biotinylated detector antibodies labeled with streptavidin?horseradish peroxidase conjugates (Strep‐HRP). The amperometric detection was performed by addition of hydrogen peroxide in the presence of hydroquinone (HQ) as the redox mediator. The dual immunosensing platform provided linear calibration ranges suitable for the determination of both biomarkers in liquid and solid clinical specimens as well as excellent selectivity against other cancer biomarkers. This simple handling dual bioplatform was applied to the determination of the soluble and extracellular fraction of the target biomarkers in serum and paraffined‐embedded tissues from colorectal cancer (CRC) patients diagnosed at different tumor grade. The obtained results reveal great potential of this configuration to improve the reliability in diagnosing metastatic CRC. 相似文献