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251.
Kimura H Fujiwara T Katoh T Nishide K Kajimoto T Node M 《Chemical & pharmaceutical bulletin》2006,54(3):399-402
(-)-Epibatidine, an excellent candidate of non-opioidal anesthesia, was formally synthesized in short steps from di-(l)-menthyl (R)-allene-1,3-dicarboxylate that was facilely prepared as a single isomer by means of crystallization-induced asymmetric transformation from a diastereomer mixture of (R)- and (S)-allene-1,3-dicarboxylates. Taking advantage of the chiral synthesis, derivatives of (-)-epibatidine were also prepared for targeting diagnostic agents that could bind nicotinic acetylcholine receptors (nAChRs) in the mammalian central nerve system. 相似文献
252.
The first series of triangular cluster complexes of [MCo(2)] (M = Rh, Ir, Ru) with a planar metalladithiolene ring coordinating in the eta(3)-bonding mode were synthesized, and the crystal structures, spectral and electrochemical properties, and thermochromism of these complexes were revealed. 相似文献
253.
Hisanori Yamane Ryouji Tanimura Junichi Takahashi Masahiko Shimada 《Journal of solid state chemistry》2006,179(1):289-295
New compounds CaY2Ge3O10 and CaY2Ge4O12 were prepared by heating mixtures of CaCO3, Y2O3 and GeO2 at 1200 °C. CaY2Ge3O10 is stable at 1300 °C, while CaY2Ge4O12 decomposes into a melt and CaY2Ge3O10 at approximately 1250 °C. We obtained single crystals of CaY2Ge3O10 by cooling a sample with an initial composition of Ca:Y:Ge=1:2:8 from 1300 °C with a rate of −6 °C/h. The crystal structure of CaY2Ge3O10 was determined by single crystal X-ray diffraction. CaY2Ge3O10 crystallizes in the monoclinic space group P21/c with a=6.0906(8), b=6.8329(8), and β=109.140(3)°, Z=4, and R1=0.029 for I>2σ(I). In the structure of CaY2Ge3O10, Ca and Y atoms are situated disorderly in three 7-fold coordination sites between isolated germanate groups of triple GeO4 tetrahedra, Ge3O10. The structural formula of CaY2Ge3O10 is expressed as (Ca0.45Y0.55)(Ca0.46Y0.54)(Ca0.09Y0.91)Ge3O10. The crystal structure of CaY2Ge4O12 was analyzed by the Rietveld method for the X-ray powder diffraction pattern. CaY2Ge4O12 is isotypic with SrNa2P4O12, crystallizing in the orthorhombic space group P4/nbm, a=9.99282(6), , Z=2, Rwp=0.092, Rp=0.067. CaY2Ge4O12 contains four-membered GeO4-tetrahedra rings, Ge4O12. Eight-fold coordinated square-anitiprism sites and 6-fold octahedral sites between the layers of the Ge4O12 rings are occupied by Y atom and Ca/Y atoms, respectively The structural formula is Y(Ca0.5Y0.5)2Ge4O12. 相似文献
254.
The chemiluminescence (CL) mechanism of 3,4-bis(3-indolyl)-1H-pyrrole-2,5-dione (IPD) was investigated using liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) of the products formed after the IPD CL reaction. We found that IPD produced strong CL via the decomposition of dioxetane formed after oxidation of the maleimide and indole moieties in the presence of CH3CN, H2O2 and NaOH. The IPD CL was used for evaluating the antioxidant effect on curcumin and epigallocatechin gallate. 相似文献
255.
Vadim A. Soloshonok Hironari Ohkura Manabu Yasumoto 《Journal of fluorine chemistry》2006,127(7):930-935
An asymmetric synthesis of (S)- and (R)-3-amino-4,4,4-trifluorobutanoic acid via DBU-catalyzed asymmetric 1,3-proton shift transfer reaction of (Z)-3-[(R)-1-phenylethylamino]-4,4,4-trifluoro-N-[(R)-1-phenylethyl]but-2-enamide has been developed. The intermediate Schiff base (S,R′)-9 was found to be relatively configurationally stable under the highly basic reaction conditions allowing preparation of the target amino acid in high chemical yield and enantioselectivity. This method was demonstrated to be practical for large (>25 g) scale synthesis of the target β-amino acid. 相似文献
256.
The characterization of the in vitro metabolites of toad venom, which has been widely used as a traditional Chinese drug, Ch'an Su, has been completed. Toad venom contains bufotoxins (such as marinobufotoxin; marinobufagin 3-suberoylarginine ester) and bufogenins (such as marinobufagin and bufalin) as the main cardiac steroids. An in vitro experiment using the rat or human liver cytosolic fraction disclosed that marinobufotoxin produced marinobufagin, but not its 3-hemisuberate. Marinobufagin was subjected to the enzyme reaction using the rat or human liver microsomal fraction together with NADPH and NAD, which produced 3-dehydromarinobufagin and 3-epimarinobufagin. Marinobufagin produced its 3-sulfate upon treatment with the rat or human liver cytosolic fraction and 3'-phosphoadenosine 5'-phosphosulfate. Bufalin was also subjected to the above enzyme reactions and showed almost the same results except for the result that the hydroxylation occurred at the 5beta-position. On the other hand, small amounts of marinobufagin 3-glucuronide were obtained only by treatment with the human liver microsomal fraction and uridine 5'-diphosphoglucuronic acid. The structures of these metabolites were confirmed using authentic samples regarding their high-performance liquid chromatographic behavior and/or liquid chromatography-mass spectrometry analysis. 相似文献
257.
Fluorescence-detected circular dichroism (FDCD) was introduced into the study of protein conformation changes. Actin was used as a model protein which undergoes dynamic conformation changes as it polymerizes. Actin labeled with N-(1-pyrene)iodoacetamide (PIA) showed monomer fluorescence peak at 386 and 410 nm, and excimer fluorescence peak at around 480 nm. Excimer was formed by PIA-dimers labeled to different sites of amino acid residues. New information concerned with actin structural changes were monitored by fluorescence emission spectra excited with left- and right-circulary polarized light at 355 nm. FDCD intensities were shown as the difference in the fluorescence emission ΔF, where ΔF=(F
L−F
R)/(F
L+F
R) denoting F
L and F
R as emissions obtained by excitation with left- and right-circulary polarized light. When solvent conditions of PIA-actin were changed by addition of NaCl, TFE, or ATP, ΔF showed sensitive responses to these compounds. From the analysis of ΔF
M and ΔF
E which represent the peaks of ΔF at the monomer- and excimer-emission band, the information concerned with the actin intrastructural changes were obtained. This method based on monitoring the excimer fluorescence with FDCD could be used for other proteins to extract finer structural changes that cannot be detected by the normal fluorescence spectroscopy. 相似文献
258.
Yoshikazu Okamoto Graham J. Kemp Tomonori Isobe Eisuke Sato Yuji Hirano Junichi Shoda Manabu Minami 《Magnetic resonance imaging》2014
Several studies have proposed the cell membrane as the main water diffusion restricting factor in the skeletal muscle cell. We sought to establish whether a particular form of exercise training (which is likely to affect only intracellular components) could affect water diffusion. The purpose of this study is to characterise prospectively the changes in diffusion tensor imaging (DTI) eigenvalues of thigh muscle resulting from hybrid training (HYBT) in patients with non-alcoholic fatty liver disease (NAFLD). Twenty-one NAFLD patients underwent HYBT for 30 minutes per day, twice a week for 6 months. Patients were scanned using DTI of the thigh pre- and post-HYBT. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), the three eigenvalues lambda 1 (λ1), λ2, λ3, and the maximal cross sectional area (CSA) were measured in bilateral thigh muscles: knee flexors (biceps femoris (BF), semitendinosus (ST), semimembranous (SM)) and knee extensors (medial vastus (MV), intermediate vastus (IV), lateral vastus (LV), and rectus femoris (RF)), and compared pre- and post-HYBT by paired t-test. Muscle strength of extensors (P < 0.01), but not flexors, increased significantly post-HYBT. For FA, ADC and eigenvalues, the overall picture was of increase. Some (P < 0.05 in λ2 and P < 0.01 in λ1) eigenvalues of flexors and all (λ1-λ3) eigenvalues of extensors increased significantly (P < 0.01) post-HYBT. HYBT increased all 3 eigenvalues. We suggest this might be caused by enlargement of muscle intracellular space. 相似文献
259.
260.