Antitumor activity of compounds isolated from leaves of Eriobotrya japonica   总被引：3，自引：0，他引：3  

Ito H  Kobayashi E  Li SH  Hatano T  Sugita D  Kubo N  Shimura S  Itoh Y  Tokuda H  Nishino H  Yoshida T 《Journal of agricultural and food chemistry》2002,50(8):2400-2403

In a search for possible antitumor agents from natural sources, megastigmane glycosides and polyphenolic constituents isolated from the leaves of Eriobotrya japonica (Rosaceae) were found to inhibit the 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced activation of Epstein-Barr virus early antigen in Raji cells. Roseoside and procyanidin B-2 were among the active compounds found in an in vitro assay; these compounds were further assessed for antitumor activity in vivo in a two-stage carcinogenesis assay on mouse skin. Roseoside significantly delayed carcinogenesis induced by peroxynitrite (initiator) and TPA (promoter), and its potency was comparable to that of a green tea polyphenol, (-)-epigallocatechin 3-O-gallate, in the same assay.  相似文献   

Identification of potent odorants in Chinese jasmine green tea scented with flowers of Jasminum sambac     

Ito Y  Sugimoto A  Kakuda T  Kubota K 《Journal of agricultural and food chemistry》2002,50(17):4878-4884

The odorants in Chinese jasmine green tea scented with jasmine flowers (Jasminum sambac) were separated from the infusion by adsorption to Porapak Q resin. Among the 66 compounds identified by GC and GC/MS, linalool (floral), methyl anthranilate (grape-like), 4-hexanolide (sweet), 4-nonanolide (sweet), (E)-2-hexenyl hexanoate (green), and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (sweet) were extracted as potent odorants by an aroma extract dilution analysis and sensory analysis. The enantiomeric ratios of linalool in jasmine tea and Jasminum sambac were determined by a chiral analysis for the first time in this study: 81.6% ee and 100% ee for the (R)-(-)-configuration, respectively. The jasmine tea flavor could be closely duplicated by a model mixture containing these six compounds on the basis of a sensory analysis. The omission of methyl anthranilate and the replacement of (R)-(-)-linalool by (S)-(+)-linalool led to great changes in the odor of the model. These two compounds were determined to be the key odorants of the jasmine tea flavor.  相似文献   

Countercurrent chromatography: liquid-liquid partition chromatography without solid support   总被引：3，自引：0，他引：3  

Y Ito  R L Bowman 《Science (New York, N.Y.)》1970,167(916):281-283

The liquid-liquid partition chromatographic system reported here involves a long helix of narrow-bore tubing. When the coiled tube is filled with one phase of a two-phase system and fed with the other phase, phase-interchange takes place in each turn of the coil, leaving a segment of the former phase as the stationary phase. Consequently, solutes present in either phase are subjected to a multistep partition process. The column efficiency, estimated on a separation of dinitrophenyl amino acids, is comparable to that of gas chromatography.  相似文献   

Void structure in colloidal dispersions     

Ito K  Yoshida H  Ise N 《Science (New York, N.Y.)》1994,263(5143):66-68

The time evolution of void structures in highly purified polymer latex dispersions was studied with a confocal laser scanning microscope. In such dispersions, which were initially homogeneous, the voids grew with time when the dispersions were kept standing and formed more quickly in the internal material than in material close to the glass-dispersion interface. Void formation is thus not an artifact arising from the presence of the interface. A similar structural inhomogeneity, in apparently homogeneous systems, is discussed for simple ionic solutions, ionic polymer solutions, and Langmuir-Blodgett films.  相似文献   

Synchrotron Infrared Absorbance Measurements of Hydrogen in MgSiO3 Perovskite     

Meade C  Reffner JA  Ito E 《Science (New York, N.Y.)》1994,264(5165):1558-1560

Micro-infrared spectroscopic measurements on single crystals of MgSiO(3) perovskite document two pleochroic hydroxyl absorbance peaks at 3483 and 3423 centimeter(-1). These measurements were obtained with the use of a synchrotron infrared source for spectroscopy. These data are consistent with a trace hydrogen content of 700 +/- 170 hydrogen atoms per 10(6) silicon atoms in the nominally anhydrous MgSiO(3) perovskite. When integrated over the volume of the lower mantle, this concentration is comparable to 12 percent of the mass of hydrogen in the Earth's hydrosphere.  相似文献   

Countercurrent chromatography with flow-through coil planet centrifuge     

Y Ito  R L Bowman 《Science (New York, N.Y.)》1971,173(995):420-422

We have developed a new method of countercurrent chromatography which employs a vertical helical tube in the centrifugal field. The helical tube is arranged so that it does not rotate as it revolves, thus eliminating the need for rotating seals. When the gyrating tube is filled with either phase and the other phase is introduced into the tube in the proper direction, an equilibrium state results in which the two phases are split into multiple alternating segments within the coil. Each phase oscillates to and fro with the rotation as the moving phase is steadily eluted out through the other end of the tube. Consequently, solutes introduced into the tube are subjected to a rapid partition process, resulting in an efficient chromatographic separation without the complications arising from solid supports. The method is illustrated by the microanalytical separation of dinitrophenyl amino acids and can be used on a preparative scale.  相似文献   

Climate-forced variability of ocean hypoxia     

Deutsch C  Brix H  Ito T  Frenzel H  Thompson L 《Science (New York, N.Y.)》2011,333(6040):336-339

Oxygen (O(2)) is a critical constraint on marine ecosystems. As oceanic O(2) falls to hypoxic concentrations, habitability for aerobic organisms decreases rapidly. We show that the spatial extent of hypoxia is highly sensitive to small changes in the ocean's O(2) content, with maximum responses at suboxic concentrations where anaerobic metabolisms predominate. In model-based reconstructions of historical oxygen changes, the world's largest suboxic zone, in the Pacific Ocean, varies in size by a factor of 2. This is attributable to climate-driven changes in the depth of the tropical and subtropical thermocline that have multiplicative effects on respiration rates in low-O(2) water. The same mechanism yields even larger fluctuations in the rate of nitrogen removal by denitrification, creating a link between decadal climate oscillations and the nutrient limitation of marine photosynthesis.  相似文献   

Negative Pressure-Temperature Slopes for Reactions Formign MgSiO3 Perovskite from Calorimetry     

Ito E  Akaogi M  Topor L  Navrotsky A 《Science (New York, N.Y.)》1990,249(4974):1275-1278

A new and sensitive differential drop solution calorimetric technique was developed for very small samples. A single experiment using one 5.18-milligram sample of perovskite, synthesized at 25 gigapascals and 1873 Kelvin, gave 110.1 +/- 4.1 kilojoules per mole for the enthalpy of the ilmenite-pervoskite transition in MgSiO(3). The thermodynamics of the reaction of MgSiO(3) (ilmenite) to MgSiO(3) (perovskite) and of Mg(2)SiO(4) (spinel) to MgSiO(3) (pervoskite) and MgO (periclase) were assessed. Despite uncertainties in heat capacity and molar volume at high pressure and temperature, both reactions clearly have negative pressure-temperature slopes, -0.005 +/- 0.002 and -0.004 +/- 0.002 gigapascals per Kelvin, respectively. The latter may be insufficiently negative to preclude whole-mantle convection.  相似文献   

Hypertriglyceridemia as a result of human apo CIII gene expression in transgenic mice   总被引：24，自引：0，他引：24  

Y Ito  N Azrolan  A O'Connell  A Walsh  J L Breslow 《Science (New York, N.Y.)》1990,249(4970):790-793

Primary and secondary hypertriglyceridemia is common in the general population, but the biochemical basis for this disease is largely unknown. With the use of transgenic technology, two lines of mice were created that express the human apolipoprotein CIII gene. One of these mouse lines with 100 copies of the gene was found to express large amounts of the protein and to be severely hypertriglyceridemic. The other mouse line with one to two copies of the gene expressed low amounts of the protein, but nevertheless manifested mild hypertriglyceridemia. Thus, overexpression of apolipoprotein CIII can be a primary cause of hypertriglyceridemia in vivo and may provide one possible etiology for this common disorder in humans.  相似文献   

Mechanism of Phreatic Eruptions at Aso Volcano Inferred from Near-Field Broadband Seismic Observations     

S Kaneshima  H Kawakatsu  H Matsubayashi  Y Sudo  T Tsutsui  T Ohminato  H Ito  K Uhira  H Yamasato  J Oikawa  M Takeo  T Iidaka 《Science (New York, N.Y.)》1996,273(5275):642-645

Broadband seismometers deployed at Aso volcano in Japan have detected a hydrothermal reservoir 1 to 1.5 kilometers beneath the crater that is continually resonating with periods as long as 15 seconds. When phreatic eruptions are observed, broadband seismograms elucidate a dynamic interplay between the reservoir and discharging flow along the conduit: gradual pressurization and long-period (approximately20 seconds) pulsations of the reservoir during the 100 to 200 seconds before the initiation of the discharge, followed by gradual deflation of the reservoir concurrent with the discharging flow. The hydrothermal reservoir, where water and heat from the deeper magma chamber probably interact, appears to help control the surface activity at Aso volcano.  相似文献