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651.
Yoshikawa K Bando S Arihara S Matsumura E Katayama S 《Chemical & pharmaceutical bulletin》2001,49(3):327-329
A new benzofuran glycoside, masutakeside I (1) and a new C10 acetylenic acid, masutakic acid A (2) were isolated from the fruiting bodies of the fungus Laetiporus sulphureus var. miniatus. Their structures were established by spectroscopic and chemical methods. The known compounds 3-6 were also obtained and identified as egonol, demethoxyegonol, egonol glucoside and egonol gentiobioside. Some of these compounds exhibited cytotoxicity against Kato III cells. 相似文献
652.
Ken-ichi Yoshikawa Yasuhiro Iwasawa 《Journal of molecular catalysis. A, Chemical》1995,100(1-3):115-127
Hydrogenation of acetophenone, 2-butanone, styrene and 1-hexene over Rh---Sn/SiO2 in heterogeneous liquid phase reaction systems was studied by in situ EXAFS, FT-IR, TEM, analytical TEM, CO and H2 adsorption measurements. The catalytic activity of Rh/SiO2 for hydrogenation of acetophenone and 2-butanone increased by a factor of 5–500 by Sn addition, showing a maximum activity at surface composition Sns/Rhs = 1.5, whereas hydrogenation of styrene and 1-hexene decreased monotonously and drastically by Sn addition. In situ Sn K-edge EXAFS of the well characterized CVD-Rh---Sn/SiO2 catalyst prepared by using Sn(CH3)4 vapor suggested that oxygen of C=O group makes a bond with Sn atom upon acetophenone adsorption. 相似文献
653.
Tabuchi M Katsuyama Y Nogami K Nagata H Wakuda K Fujimoto M Nagasaki Y Yoshikawa K Kataoka K Baba Y 《Lab on a chip》2005,5(2):199-204
We report here advanced microchip electrophoresis using a nanoparticle doped polymer solution that enables greater separation of DNA. The proposed system is simple and effective without any new apparatus or complicated procedures. Various amounts and sizes (80 nm, 110 nm, and 193 nm) of polymer nanoparticle solutions (PEGylated-latex) were mixed with a conventional polymer solution for microchip electrophoresis. When a 0.49 wt% hydroxyl propyl methyl cellulose (HPMC) buffer solution was mixed with a 2.25 wt% 80 nm-PEGylated-latex a higher separation efficiency and a higher mobility of a wider molecular range of dsDNA (10 bp to 2 kbp) was achieved under low viscosity conditions (<5.5 cP) than in conventional 0.7% HPMC. The separation performance was dependent on the particle size and concentration. Furthermore, the effectiveness of the larger PEGylated-latex (193 nm) was not as high as the smaller one (80 to 110 nm). The observed separation improvement by polymer solution with latex-nanoparticles seems to derive from the balance between wider polymer mesh size and the structural obstacles of particles in the buffer. 相似文献
654.
Sergeyev VG Novoskoltseva OA Pyshkina OA Zinchenko AA Rogacheva VB Zezin AB Yoshikawa K Kabanov VA 《Journal of the American Chemical Society》2002,124(38):11324-11333
Interaction of salmon sperm DNA (300-500 bp) and ultrahigh molecular mass DNA (166 kbp) from bacteriophage T4dC with linear poly(N-diallyl-N-dimethylammonium chloride) (PDADMAC) and slightly cross-linked (#) PDADMAC (#PDADMAC) hydrogel in water has been studied by means of UV-spectroscopy, ultracentrifugation, atomic force, and fluorescence microscopy (FM). It is found that the linear polycation induced compaction of either native (double-stranded) or denatured (single-stranded) DNA by forming PDADMAC-DNA interpolyelectrolyte complexes (IPEC)s. At the same time, #PDADMAC hydrogel is able to distinguish between native and denatured DNA. Native DNA is adsorbed and captured in the hydrogel surface layer, while denatured DNA diffuses to the hydrogel interior until the whole hydrogel sample is transformed into the cross-linked IPEC. Both native and denatured DNA can be completely released from the hydrogel in appropriate conditions with no degradation by adding a low molecular salt. The data observed using conventional physicochemical methods with respect to DNA of a moderate molecular mass remarkably correlate with the pictures directly observed for ultrahigh molecular mass DNA in dynamics by using FM. 相似文献
655.
M Yoshikawa E Uchida N Chatani N Murakami J Yamahara 《Chemical & pharmaceutical bulletin》1992,40(11):3121-3123
Six new antiallergic and antimicrobial principles, thunberginols A, B, C, D, E, and F, were isolated from Hydrangeae Dulcis Folium, the fermented and dried leaves of Hydrangea macrophylla SERINGE var. thunbergii MAKINO. The chemical structures of thunberginols A, B, and F have been determined on the basis of chemical and physiocochemical evidence. Thunberginols A, B, and F showed more potent antiallergic activity than phyllodulcin, hydrangenol, and AA-861 in the in vitro test using the Schults-Dale reaction in sensitized guinea pig bronchial muscle. Thunberginols A, B, and F also exhibited antimicrobial activity against oral bacteria. 相似文献
656.
657.
Murakami T Nakamura J Matsuda H Yoshikawa M 《Chemical & pharmaceutical bulletin》1999,47(12):1759-1764
The saponin fraction from the seeds of the tea plant, Camellia sinensis L. var. assamica Pierre cultivated in Sri Lanka, was found to show a potent protective effect on gastric mucosal lesions induced by ethanol in rats. Nine new acylated polyhydroxyoleanene-type triterpene oligoglycosides called assamsaponins A-I were isolated from the active saponin fraction together with three known saponins, theasaponin E1 and E2 and camelliasaponin B1. The structures of assamsaponins A-E were elucidated on the basis of chemical and physicochemical evidence. Theasaponin E1 exhibited potent gastroprotective activity. 相似文献
658.
The photoelectron spectra of the nitroxide radicals, di-tert-butylnitroxide (DTBN) and 2,2,6,6-tetramethyl-piperidine-N-oxyl, have been studied and molecular orbital calculations made. The adiabatic first ionization potentials were found to be 6.77 and 6.73 eV for these two nitroxide radicals respectively. Four vertical ionization potentials which are common to each nitroxide radical were attributed to ionization of the odd electron in the NO anti-bonding π orbital, oxygen lone pair electrons and NO bonding π electrons. Doublet splitting of the lone pair electron peak with different peak intensities can be quantitatively understood in terms of triplet and singlet states of the photoionized nitroxide cation. 相似文献
659.
Nakashima N Tanaka Y Tomonari Y Murakami H Kataura H Sakaue T Yoshikawa K 《The journal of physical chemistry. B》2005,109(27):13076-13082
Aqueous dispersions of fullerene C70-filled carbon nanotubes (C70@SWNTs or peapods) and empty single-walled carbon nanotubes (empty SWNTs) were prepared with the aid of trimethyl-(2-oxo-2-pyrene-1-yl-ethyl)-ammonium bromide (1), which is a carbon nanotube solubilizer. This is the first report describing the preparation and characterization of the transparent dispersion/dissolution of the peapods. The UV-vis-near-IR spectra of C70@SWNTs-1 and empty SWNTs-1 were almost identical. We found by means of transmission electron microscopy and atomic force microscopy that the empty SWNTs and C70-peapods form helical nanostructures in the shapes of rings, irregular rings, lassos, handcuffs, catenanes, pseudorotaxanes, and figure-eight structures. The mechanism of the superstructure formation has been discussed in relation to the unique characteristics of stiff polymer chains with the aid of an off-lattice Monte Carlo simulation. 相似文献
660.
A novel bis(L-carnitinato)Zn(II) complex, Zn(car)(2)Cl(2), was prepared, and its insulinomimetic and antidiabetic activities were examined. The complex showed a tendency to lower the high blood glucose levels of KK-A(y) mice with type 2 diabetes mellitus when given by oral administration at a dose of 20 mg Zn/kg body weight for 16 d. In addition, the complex improved glucose tolerance ability when examined by the oral glucose tolerance test (1 g glucose/kg body weight). 相似文献