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91.
Applied Biochemistry and Biotechnology - 相似文献
92.
Applied Biochemistry and Biotechnology - 相似文献
93.
94.
Yan B Collins N Wheatley J Irving M Leopold K Chan C Shornikov A Fang L Lee A Stock M Zhao J 《Journal of combinatorial chemistry》2004,6(2):255-261
We have developed a high-throughput purification system to purify combinatorial libraries at a 50-100-mg scale with a throughput of 250 samples/instrument/day. We applied an accelerated retention window method to shorten the purification time and targeted one fraction per injection to simplify data tracking, lower QC workload, and simplify the postpurification processing. First, we determined the accurate retention time and peak height for all compounds using an eight-channel parallel LC/UV/MS system, and calculated the specific preparative HPLC conditions for individual compounds. The preparative HPLC conditions include the compound-specific gradient segment for individual compounds with a fixed gradient slope and the compound-specific UV or ELSD threshold for triggering a fraction collection device. A unique solvent composition or solvent strength was programmed for each compound in the preparative HPLC in order to elute all compounds at the same target time. Considering the possible deviation of the predicted retention time, a 1-min window around the target time was set to collect peaks above a threshold based on UV or ELSD detection. Dual column preparative instruments were used to maximize throughput. We have purified more than 500 000 druglike compounds using this system in the past 3 years. We report various components of this high-throughput purification system and some of our purification results. 相似文献
95.
Dendritic molecular capsules for hydrophobic compounds 总被引:1,自引:0,他引:1
Morgan MT Carnahan MA Immoos CE Ribeiro AA Finkelstein S Lee SJ Grinstaff MW 《Journal of the American Chemical Society》2003,125(50):15485-15489
Reichardt's dye, a highly solvatochromic dye, was encapsulated within poly (glycerol succinic acid) ([Gn]-PGLSA-OH) dendrimers to investigate the interior environment of these dendritic macromolecules. The absorption maximum for the encapsulated Reichardt's dye in water was indicative of a relatively high dielectric constant present within the dye/dendrimer complex. (1)H NMR of the encapsulated complex showed the presence of aromatic protons from Reichardt's dye along with the aliphatic protons of the dendrimer. Additionally, there were substantial changes in T(1) and T(2) times of the encapsulated dye when compared with the free dye, and (1)H NOESY spectra for the complex showed a significant number of intermolecular NOE cross-peaks. These data reveal the close through-space proximity of the dye to the dendrimer and the restricted motion of the encapsulated dye. To demonstrate the potential use of these macromolecules as drug delivery vehicles, the poorly water-soluble anticancer drug 10-hydroxycamptothecin (10HCPT) was encapsulated within a carboxylated PGLSA dendrimer ([G4]-PGLSA-COONa). Cytotoxicity assays with human breast cancer cells showed a significant reduction of cell viability, demonstrating that 10HCPT retains activity upon encapsulation. 相似文献
96.
Simultaneous analysis of oxidized and reduced glutathione in cell extracts by capillary zone electrophoresis 总被引:1,自引:0,他引:1
Yang Q Krautmacher C Schilling D Pittelkow MR Naylor S 《Biomedical chromatography : BMC》2002,16(3):224-228
Glutathione (GSH) and glutathione disulfide (GSSG) levels in cells constitute a thiol redox system. They can be used as an indicator of oxidative stress of the cell. In this study, a capillary zone electrophoresis (CZE) method is described that enables quantitation of GSH and GSSG from cellular extracts. The CZE buffer used was 20 mM ammonium acetate containing 5% (v/v) acetic acid at pH 3.1 in conjunction with a polybrene coated capillary operated in reverse polarity mode. Effects of different acids used to prepare cell samples were investigated on CZE performance. The acids include meta phosphoric acid (MPA), trichloroacetic acid (TCA), phosphoric acid (PA) and sulfosalicylic acid (SSA) and are used to stabilize GSH and GSSG before performing CZE analysis. The method features a limit of detection of 4 microM and a limit of quantitation of 12 microM for both GSSG and GSH and recoveries of 94% for GSH and 100% for GSSG. Quantitative analysis of GSSG and GSH in HaCaT cell extracts (5% SSA, w/v) was performed with this method and changes in the ratio of GSH to GSSG in N-ethylmaleimide treated cell sample was observed by comparing with control cell samples. 相似文献
97.
Szklarzewicz Janusz Samotus Alina Nowicka Beata Burgess John Fawcett John Russell David R. 《Transition Metal Chemistry》1999,24(2):177-182
The X-ray crystal structure of (bpyH2)2[W(CN)8]·4H2 O (bpyH2=2,2-bipyridinium) is described. The [W(CN)8]4– anion has an approximately square antiprismatic (D4d) conformation, seemingly imposed by strong anion–water–cation hydrogen-bonding interactions. Bond distances in the anion are: WC 2.150(5), 2.163(5); CN 1.128(6), 1.145(6)Å and the angles WCN are 177.6(5), 178.3(5)°. The dihydrate and the anhydrous salt are both intensely black solids, exhibiting ion-pair charge-transfer interaction between cation and anion. E.s.r. spectra indicate that 30% of the tungsten is present as WV in the solid state, but that in solution only the WIV complex is present. The electron withdrawing effect of the cation is discussed and compared with that in a series of salts with different bipyridinium cations. 相似文献
98.
Mark S. Wrighton 《Journal of organometallic chemistry》1976,120(3):C58-C62
Photolysis of 1,2-divinyl- and 1-phenyl-2-vinyltetramethyldisilane and 1-phenylethenylpentamethyldisilane has been investigated. All three compounds afforded a new type of silicon—carbon double-bonded intermediate via photorearrangement of a silyl group to the terminal carbon of a vinyl group. 相似文献
99.
100.
Ningyi Chen Jiayi Xu Michael Reuman Xun Li Ronald K. Russell Zhihua Sui 《Tetrahedron letters》2006,47(33):5909-5913
Various substituents were introduced onto the methyl group in 4-methyl coumarins through lithiation, followed by reactions with a wide range of electrophiles. The presence of an alkoxy group on 6′-phenyl ring was found to be pivotal for the success of this reaction. This procedure provided a convenient synthetic pathway to elaborate the methyl group of 4-methylcoumarins. Application of this methodology was showcased with the synthesis of biologically important novel tetracyclic chromene ring systems (n = 1-3). 相似文献