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441.
De Bock L Vande Casteele SR Mulliez SM Boussery K Van Bocxlaer JF 《Journal of chromatography. A》2011,1218(6):793-801
For the determination of the in vitro cytochrome P450 activity in microsomes, a quantification method for the probe metabolites, formed during incubation, is required. Due to insufficient sensitivity of a previously developed high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for some of the metabolites, a fast and easy derivatization method with pyridine-3-sulfonyl chloride (PS) is described. Acetaminophen (CYP1A2), dextrorphan (CYP2D6), hydroxy-chlorzoxazone (CYP2E1) and hydroxy-mephenytoin (CYP2C19) can be derivatized because of the presence of a phenolic OH, whereas hydroxy-midazolam (CYP3A4) and hydroxy-tolbutamide (CYP2C9) remain unchanged. As PS improves the ionization efficiency in the positive electrospray ionization (ESI) mode, the sensitivity of the detection is improved significantly and meets requirements for the activity determination. Native negative electrospray type molecules, moreover, become positive ESI candidates. The direct derivatization in the aqueous incubation medium, without any other sample pre-treatment steps, such as evaporation or extraction, makes this procedure easy to perform. The method using 20s microwave irradiation was shown to equal a 10min reaction in a 60°C heating block, consequently simplifying and shortening the process. Collision induced fragmentation of the derivatives resulted in at least one native compound, rather than derivative, specific product ion, thereby improving the selectivity of the method in the multiple reaction monitoring mode. The HPLC-MS/MS method was validated, and was demonstrated to be sensitive, selective, precise and accurate. The absence of a relative matrix effect was established, notwithstanding that an absolute matrix effect was observed. The analysis of a sample after microsomal incubation, from which some of the metabolites could not be quantified using the method without derivatization, proved the usefulness of the method. 相似文献
442.
In view of glycomics studies in plants, it is important to have sensitive tools that allow one to analyze and characterize the N-glycans present on plant proteins in different species. Earlier methods combined plant-based sample preparations with CE-LIF N-glycan analysis but suffered from background contaminations, often resulting in non-reproducible results. This publication describes a reproducible and sensitive protocol for the preparation and analysis of plant N-glycans, based on a combination of the 'in-gel release method' and N-glycan analysis on a multicapillary DNA sequencer. Our protocol makes it possible to analyze plant N-glycans starting from low amounts of plant material with highly reproducible results. The developed protocol was validated for different plant species and plant cells. 相似文献
443.
The total synthesis of enantiopure 4-epi-(+)-codonopsinine was achieved in 10 steps starting from D-ribose as a chiral building block. The key step involved a highly stereoselective nucleophilic addition of a Grignard reagent to a protected ribosylamine. Synthesis of the N-desmethyl derivative and its p-tolyl analogue was also accomplished, and the compounds were assayed against α-fucosidase. 相似文献
444.
Mark Damen Mario A. Izidoro Debora N. Okamoto Lilian C. G. Oliveira Helene I. V. Amatdjais-Groenen Stijn F. M. van Dongen Koen W. R. van Cleef Ronald P. van Rij Cindy E. J. Dieteren Daniel Girons Bernd N. M. van Buuren Byron E. E. Martina Albert D. M. E. Osterhaus Luiz Juliano Bob J. Scholte Martin C. Feiters 《Molecules (Basel, Switzerland)》2022,27(10)
Dengue is an important arboviral infectious disease for which there is currently no specific cure. We report gemini-like (geminoid) alkylated amphiphilic peptides containing lysines in combination with glycines or alanines (C15H31C(O)-Lys-(Gly or Ala)nLys-NHC16H33, shorthand notation C16-KXnK-C16 with X = A or G, and n = 0–2). The representatives with 1 or 2 Ala inhibit dengue protease and human furin, two serine proteases involved in dengue virus infection that have peptides with cationic amino acids as their preferred substrates, with IC50 values in the lower µM range. The geminoid C16-KAK-C16 combined inhibition of DENV2 protease (IC50 2.3 µM) with efficacy against replication of wildtype DENV2 in LLC-MK2 cells (EC50 4.1 µM) and an absence of toxicity. We conclude that the lysine-based geminoids have activity against dengue virus infection, which is based on their inhibition of the proteases involved in viral replication and are therefore promising leads to further developing antiviral therapeutics, not limited to dengue. 相似文献
445.
Dr. Bethany R. Hood Dr. Yovan de Coene Afonso V. Torre Do Vale Froes Dr. Claire F. Jones Dr. Pierre Beaujean Dr. Vincent Liégeois Dr. Fraser MacMillan Prof. Benoît Champagne Prof. Koen Clays Dr. John Fielden 《Angewandte Chemie (International ed. in English)》2023,62(5):e202215537
Electrochemically switched 2nd order non-linear optical responses have been demonstrated for the first time in polyoxometalates (POMs), with an arylimido-derivative showing a leading combination of high on/off contrast (94 %), high visible transparency, and cyclability. Spectro-electrochemical and TD-DFT studies indicate that the switch-off results from weakened charge transfer (CT) character of the electronic transitions in the reduced state. This represents the first study of an imido-POM reduced state, and demonstrates the potential of POM hybrids as electrochemically activated molecular switches. 相似文献