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121.
Determination of Glimepiride in Human Plasma by LC-MS-MS and Comparison of Sample Preparation Methods for Glimepiride 总被引:1,自引:0,他引:1
Hohyun Kim Kyu Young Chang Chang Hun Park Moon Sun Jang Jung-Ae Lee Hee Joo Lee Kyung Ryul Lee 《Chromatographia》2004,60(1-2):93-98
A sensitive and selective method for quantitation of glimepiride in human plasma was established using liquid chromatography-electrospray ionization tandem mass spectrometry. Three different methods for the sample preparation of glimepiride and an internal standard were investigated (liquid-liquid extraction, solid-phase extraction and protein precipitation). Glipizide was used as an internal standard. Compounds were separated on a C18 column with 80% acetonitrile and 20% deionized water (adjusted to pH 3.5 with acetic acid), as mobile phase at a flow rate of 200 L min–1. By use of multiple reaction monitoring mode in MS-MS with liquid-liquid extraction and solid-phase extraction, glimepiride and glipizide were detected without severe interference from the human plasma matrix. Glimepiride produced a protonated precursor ion ([M+H]+) at m/z 491 and a corresponding product ion at m/z 352, and the internal standard produced a protonated precursor ion ([M+H]+) at m/z 446 and a corresponding product ion at m/z 321. The limit of quantitation was 0.1 ng mL–1, 0.5 ng mL–1 and 1.0 ng mL–1 when using liquid-liquid extraction, solid-phase extraction and protein precipitation, respectively. The validation, reproducibility, stability, and recovery of the different sample preparation methods were comparable and all the methods gave reliable results. The method has been successfully applied to pharmacokinetic study of glimepiride in human plasma. 相似文献
122.
Jew SS Jeong BS Lee JH Yoo MS Lee YJ Park BS Kim MG Park HG 《The Journal of organic chemistry》2003,68(11):4514-4516
Systematic investigations to develop an efficient enantioselective synthetic method for alpha-alkyl-alanine by catalytic phase-transfer alkylation were performed. The alkylation of 2-naphthyl aldimine tert-butyl ester, 1E, with RbOH and O(9)-allyl-N-2',3',4'-trifluorobenzylhydrocinchonidinium bromide, 6, at -35 degrees C showed the highest enantioselectivities, up to 96% ee. 相似文献
123.
Noveron JC Lah MS Del Sesto RE Arif AM Miller JS Stang PJ 《Journal of the American Chemical Society》2002,124(23):6613-6625
We report the supramolecular chemistry of several metal complexes of N-(4-pyridyl)benzamide (NPBA) with the general formula [Ma(NPBA)2AbSc], where M = Co2+, Ni2+, Zn2+, Mn2+, Cu2+, Ag+; A = NO3-, OAc-; S = MeOH, H2O; a = 0, 1, 2; b = 0, 1, 2, 4; and c = 0, 2. NPBA contains structural features that can engage in three modes of intermolecular interactions: (1) metal-ligand coordination, (2) hydrogen bonding, and (3) pi-pi stacking. NPBA forms one-dimensional (1-D) chains governed by hydrogen bonding, but when reacted with metal ions, it generates a wide variety of supramolecular scaffolds that control the arrangement of periodic nanostructures and form 1- (2-4), 2- (5), or 3-D (6-10) solid-state networks of hydrogen bonding and pi-pi stacking interactions in the crystal. Isostructural 7-9 exhibit a 2-D hydrogen bonding network that promotes topotaxial growth of single crystals of their isostructural family and generates crystal composites with two (11) and three (12) different components. Furthermore, 7-9 can also form crystalline solid solutions (M,M')(NPBA)2(NO3)2(MeOH)2 (M, M' = Co2+, Ni2+, or Zn2+, 13-16), where mixtures of Co2+, Ni2+, and Zn2+ share the same crystal lattice in different proportions to allow the formation of materials with modulated magnetic moments. Finally, we report the effects that multidimensional noncovalent networks exert on the magnetic moments between 2 and 300 K of 1-D (4), 2-D (5), and 3-D (7, 8, 10, and 13-16) paramagnetic networks. 相似文献
124.
Yunxuan Wang Kwang Ho Kim Keunhong Jeong Nak-Kyoon Kim Chang Geun Yoo 《Current Opinion in Green and Sustainable Chemistry》2021
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125.
Extracellular signal-regulated kinase (ERK) is a key regulatory enzyme mediating cell responses to mitogenic stimulation and is one of the key components in linking growth factor receptor activation to serine/threonine protein phosphorylation processes. Phosphorylation reaction by ERK plays an important role in many signal transduction pathways. ERK phosphorylates numerous substrates such as MBP, microtubule-associated protein 2 (MAP2) and nuclear protein. In particular, MBP is a substrate commonly employed for the detection of ERK activity and contains the consensus primary sequence PRT97P. In this paper, we compared the degree of the phosphorylation reaction of MBP substrate peptides by ERK with the three different MBP substrate peptides, MBP1(KNIVTPRTPPPSQGK), MBP2(VPRTPGGRR) and MBP3(APRTPGGRR) in order to select an efficient substrate peptide for phosphorylation reaction by ERK. The results showed that the MBP3 peptide is the most efficient substrate for phosphorylation reaction by ERK. Using MBP3 peptide, the phosphorylation reaction of MBP by ERK was monitored with both matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and capillary electrophoresis (CE). Our results demonstrate the feasibility of the CE method, the method being a simple and reliable technique in determining and characterizing various kinds of enzyme reaction especially including kinase enzymes. 相似文献
126.
1-(p-Substituted phenyl)-2-vinylcyclopropanes such as 1-phenyl-2-vinylcyclopropane (Ia), 1-(p-chlorophenyl)-2-vinylcyclopropane (Ib), 1-(p-anisyl)-2-vinylcyclopropane (Ic), and 1-(p-tolyl)-2-vinylcyclopropane (Id) were prepared and polymerized radically, cationically and with Ziegler–Natta catalysts. Ia and Ib polymerized exclusively in 1,5-fashion with radical initiators. However, Ic and Id polymerized in 1,5-fashion only with Ziegler–Natta catalysts. All polymers were soluble in ordinary organic solvent and solution-cast films were clear and flexible, showing Tg values in the range of 39–71°C. Spectral data indicated that the double bonds of the polymer chains were in trans form in all cases. The difference between the polymerizabilities of different monomers are interpreted in terms of electronic properties of substituents. 相似文献
127.
The effect of terminal groups of oligomer electrolytes on the photovoltaic performance of dye-sensitized solar cells (DSSCs) have been systematically investigated to show that the terminal group plays a critical role in determining the concentration of I(3)(-), ionic conductivity, flatband potential and consequently the energy conversion efficiency. 相似文献
128.
129.
Molecular reorientation in the presence of internal rotation is investigated and an analytical expression for the spin—rotational rate of a nucleus attached to the internal rotor is obtained in terms of the internal angular-momentum correlation time. A model of a symmetric-top molecule undergoing anisotropic rotational diffusion is extended to include a modified extended diffusion of internal rotation. The result is applied to liquid toluene and the internal angular-momentum correlation time is evaluated from the 13C nuclear spin—rotational relaxation rate of the methyl carbon. A comparison with the previous result on the dipole—dipole relaxation data is made and the consistency of the present theory is discussed. 相似文献
130.
Changho Yoo Henry M. Dodge Alexandra H. Farquhar Kristen E. Gardner Alexander J. M. Miller 《Chemical science》2020,11(44):12130
A unique chain-rupturing transformation that converts an ether functionality into two hydrocarbyl units and carbon monoxide is reported, mediated by iridium(i) complexes supported by aminophenylphosphinite (NCOP) pincer ligands. The decarbonylation, which involves the cleavage of one C–C bond, one C–O bond, and two C–H bonds, along with formation of two new C–H bonds, was serendipitously discovered upon dehydrochlorination of an iridium(iii) complex containing an aza-18-crown-6 ether macrocycle. Intramolecular cleavage of macrocyclic and acyclic ethers was also found in analogous complexes featuring aza-15-crown-5 ether or bis(2-methoxyethyl)amino groups. Intermolecular decarbonylation of cyclic and linear ethers was observed when diethylaminophenylphosphinite iridium(i) dinitrogen or norbornene complexes were employed. Mechanistic studies reveal the nature of key intermediates along a pathway involving initial iridium(i)-mediated double C–H bond activation.A unique chain-rupturing transformation that converts an ether functionality into two hydrocarbyl units and carbon monoxide is reported. 相似文献