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991.
Zhao C Nagatsu A Hatano K Shirai N Kato S Ogihara Y 《Chemical & pharmaceutical bulletin》2003,51(3):255-261
Two new podophillotoxin glucosides, L-picropodophillotpxin 7'-O-(beta-D-glucopyranosyl-(1-->6)-beta-D-glucopyranoside) (2) and L-picropodophillotpxin 7'-O-beta-D-glucopyranoside (3), were isolated from Chinese medicinal plant, Sinopodophillum emodi, together with 4 known compounds, podophillotoxin (1), podorhizol 4'-O-beta-D-glucopyranoside (4), deoxypodophillotoxin (5), and dehydropodophillotoxin (6). The structures of 2 and 3 were finally determined by the extensive decouping and nuclear Overhauser effect (NOE) experiments in NMR spectra and circular dichroism (CD) spectra. Compound 2 is the second example of podophillotoxin diglucoside, and both the first one and 2 were isolated from S. emodi. X-ray crystal structure analysis of 1, 5, and 6 was carried out. Compounds 1 and 5 showed the different conformations from those reported. 相似文献
992.
Maekawa Y Inaba T Hobo H Narita T Koshikawa H Moon S Kato J Yoshida M 《Chemical communications (Cambridge, England)》2002,(18):2088-2089
Radiation-induced reactions of cinnamic acid derivatives have been examined and compared with photoreactions in the crystalline state; all the reaction products were exactly the same as those of the photoreactions, indicating that the reactions proceed only via the lowest excited state to give [2 + 2] cycloadducts, E/Z isomerization products, or starting molecules. 相似文献
993.
Masahiro Kurakake Takeshi Shirasawa Hiroshi Ooshima Alvin O. Converse Jyoji Kato 《Applied biochemistry and biotechnology》1995,50(3):231-241
Three empirical rate expressions, Kinetics I, II, and III, for the enzymatic hydrolysis of cellulose were evaluated in an
effort to develop a easy-to-use rate expression. They are based on the following equation:-dV/dX = kV, where V and X are the hydrolysis rate and the fractional conversion. In Kinetic I,k is constant. In Kinetic II, a linear relatinship betweenk and t is assumed. In Kinetic III, an exponential relationship is assumed. The three expressions were applied to enzymatic
hydrolysis carried out under seven different conditions in which the kinds of substrates, enzymes, and initial concentrations
were varied. All of the examined rate expressions were applied to the hydrolysis with success, but the better accuracies were
obtained by Kinetic III, Kinetic II, and Kinetic I in this order. The variations ofk with time found in this study, especially the exponential relationship, were consistent with the effect of the measured changes
in the concentration of adsorbed enzyme as predicted by theory developed previously by Ooshima et al. (1). 相似文献
994.
A carbon-carbon bond was formed at the β-position of cyclic ketones in a one-pot manner by oxidation with N-tert-butylbenzenesulfinimidoyl chloride, followed by the reaction of malonic acid esters or potassium cyanide. 相似文献
995.
In the 21st century, soft materials will become more important as functional materials because of their dynamic nature. Although soft materials are not as highly durable as hard materials, such as metals, ceramics, and engineering plastics, they can respond well to stimuli and the environment. The introduction of order into soft materials induces new dynamic functions. Liquid crystals are ordered soft materials consisting of self-organized molecules and can potentially be used as new functional materials for electron, ion, or molecular transporting, sensory, catalytic, optical, and bio-active materials. For this functionalization, unconventional materials design is required. Herein, we describe new approaches to the functionalization of liquid crystals and show how the design of liquid crystals formed by supramolecular assembly and nano-segregation leads to the formation of a variety of new self-organized functional materials. 相似文献
996.
Michinori Akaiwa Hiroki Fukumoto Takakazu Yamamoto 《Journal of organometallic chemistry》2005,690(18):4192-4196
Thioamide-based tridentate ligands, 1,3-benzenedicarbothioamides (1a-c), were used to afford pincer palladium(II) complexes (Pd(1-H)Cl, 2a-c) with η3-S,C,S type coordination. The complexes exhibit strong emission in a glassy frozen state as well as in the solid state. The decay lifetime of the emission from the complexes is in a range of 8-9 × 10−5 s, which is indicative of phosphorescent emission. 相似文献
997.
The optimum conditions for the coupling of proteins were investigated using TSKgel Tresyl-Toyopearl 650M. They were dependent on the proteins coupled. For example, when soybean trypsin inhibitor was coupled at pH 8 the coupling was completed within 1 h and the subsequent adsorption capacity for trypsin was maximal. Longer coupling times decreased the adsorption capacity due to multi-point attachment. The adsorbents obtained were successfully used for affinity chromatography in a short time. 相似文献
998.
Syntheses of (S)-chroman-2-carboxaldehyde congener 1 and (S)-chiral isoprene unit 3 were achieved based on the enzymatic acetylation of (+/-)-chroman-2-methanol 6 and (+/-)-(2,3)-anti-2-methyl-3-(p-methoxyphenyl)-1,3-propane diol 12, respectively. Synthesis of the side-chain part corresponding to (3R,7R)-3,7,11-trimethyldodecan-1-ol 27 was achieved by the coupling reaction of (S)-3 and (R)-3,7-dimethyloctyl iodide 4. The Wittig reaction of (3R,7R)-phosphonium salt 2 derived from (3R,7R)-27 and (S)-1 gave the olefin 28 which was subjected to catalytic hydrogenation to afford (2R,4'R,8'R)-alpha-tocopherol. 相似文献
999.
Two new furanosesterterpenes have been isolated from the marine sponge C. scalaris as inhibitors of the cell division of fertilized starfish eggs. 相似文献
1000.