A novel neutral polysaccharide having activity on the reticuloendothelial system from the root of Glycyrrhiza uralensis

A neutral polysaccharide, named glycyrrhizan UC, was isolated from the root of Glycyrrhiza uralensis Fischer. It was homogeneous on electrophoresis and gel chromatography, and its molecular mass was estimated to be 69,000. Glycyrrhizan UC is composed of L-arabinose:D-galactose:D-glucose:L-rhamnose in the molar ratio of 10:30 27:1. Methylation analysis, carbon-13 nuclear magnetic resonance and periodate oxidation studies indicated its structural feature as an arabino-3,6-galacto-glucan type polysaccharide.     

Effect of solvent on an NMR chemical shift difference between glycyl geminal alpha-protons as a probe of beta-turn formation of short peptides

Proton NMR spectra of short peptides with a glycyl (Gly) or N-methylglycyl (sarcosyl, Sar) residue were measured in various mixed solvents with a wide range of dielectric constants: 78.3-2.3. From analyses of the octet and quartet signals of the geminal alpha-protons of Gly and Sar residues, respectively, we have estimated chemical shift differences between the two alpha-protons, Delta delta(alpha/alpha'). It is found that the Delta delta(alpha/alpha') values increase with decreasing solvent polarity and the increasing rates depend significantly on amino acid sequences. By referring to infrared spectra and chemical shift of the terminal NH protons, deltaNH, of the peptides, the Delta delta(alpha/alpha') values were found to be a good probe of beta-turn formation. From solvent-dependent change of Delta delta(alpha/alpha'), we estimated the free energies for the beta-turn formation and compared the results with those estimated from deltaNH. Using the resulting free energies, we have discussed effects of solvent on the beta-turn formation.     

Spectroscopic study of mutual solubilities of water and benzene at high temperatures and pressures

Near-infrared and ultraviolet absorption of water-benzene mixtures has been measured at temperatures and pressures in the ranges of 323-673 K and 50-400 bar, respectively. Concentrations of water and benzene in both the water-rich phase and the benzene-rich phase of the mixtures were obtained from absorption intensities of near-infrared bands of water and benzene and ultraviolet bands of benzene. Mutual solubilities in molar fractions increase remarkably with increasing temperature at pressures in the two-liquid-phase coexistence region, and are consistent with previously reported values. It proves that the solubility of benzene in water is an order of magnitude smaller than that of water in benzene throughout the two-phase region. In addition, it is found that effect of pressure on the solubilities is opposite between water in benzene and benzene in water. These solubility properties are discussed on the basis of a cavity-based solvation model. It is suggested that the asymmetry in the mutual solubility and the opposite direction of the pressure effect are caused by difference in molecular size and difference in thermal compressibility, respectively, between water and benzene.     

Study on the Morphological Change of Growing Ag Crystallites by in-situ SEM Observation

The morphology of the initial growth stage of Ag thin films on Mo(110) substrate was investigated in-situ by the scanning electron microscope (SEM). A great majority of the Ag crystallites showed a truncated Wulff's equilibrium shape of the face-centered-cubic (fcc) structure with epitaxial orientation [1 0]Ag//[11 ]Mo, (111)Ag//(110)Mo with the substrate temperature of 400 °C. In-situ SEM observation during the growth revealed two kinds of particular morphological change of Ag crystallites, namely (1) rotation of an Ag crystallite and (2) reformation of the crystal faces of the Ag crystallite. However, a small number of Ag crystal particles showed Wulff-polyhedron truncated by the (100) plane parallel to the substrate surface (oriented to the 〈100〉 axis normal to the substrate surface).     

A new, highly sensitive time-of-flight mass spectrometer consisting of a flangeon-type conical ion lens system and a proto-type Daly detector for exhaust gas analysis based on the Jet-REMPI technique.

For the analysis of trace amounts of hazardous organic compounds, we developed a new ion detection system for supersonic jet resonance-enhanced multiphoton laser ionization mass spectrometry. High sensitivity and selectivity have been achieved by combining a proto-type Daly detector, a newly designed conical ion lens, and a potential switch that can perform the function of a mass selector. This ion detection system enables us to bring the jet nozzle closer to the ionization point. The detection sensitivity has thus been improved totally by more than 100 times compared with that obtained by the parallel-plate electrodes and micro-channel plate. We succeeded in assembling a flangeon-type ion extraction electrode consisting of a conical ion lens and a potential switch.     

Alkali and Alkaline Earth Metal Ions Complexes with a Partial Peptide of the Selectivity Filter in K+ Channels Studied by a Cold Ion Trap Infrared Spectroscopy

The infrared (IR) spectra of alkali and alkaline earth metal ion complexes with the Ac-Tyr-NHMe (GYG) peptide have been measured by laser photodissociation in a cold ion trap coupled with an electrospray mass spectrometer. The GYG peptide corresponds to a portion of the ion selectivity filter in the KcsA K⁺ channel that allows K⁺ to pass, but blocks Na⁺ even though it has a smaller ionic radius than K⁺. This current study extends a previous investigation on Na⁺ and K⁺ to the entire set of alkali metaI ions and alkaline earth dications. IR-IR hole-burning (IR² dip) spectroscopy has established the coexistence of several conformers of the GYG-metal ion complexes. The structures of the conformers were assigned by comparison between the isomer-selected IR spectra and theoretical IR spectra obtained from quantum chemical calculations. It was found that the structure of the dominant conformer correlates with the ability of the ion to permeate through the K⁺ channel.     

Formulation,Characterization and Permeability Studies of Fenugreek (Trigonella foenum-graecum) Containing Self-Emulsifying Drug Delivery System (SEDDS)

Fenugreek is used as a spice and a traditional herbal medicine for a variety of purposes, given its antidiabetic and antioxidant effects. Self-emulsifying drug delivery systems (SEDDS) of herbal drugs are targets of extensive research aiming to increase bioavailability and stability. The study’s objective was to formulate SEDDS containing Trigonella foenum-graecum extract to improve the stability of herbal extract and to increase their permeability through a Caco-2 monolayer. A characterized fenugreek dry extract was used for the formulations, while the SEDDS properties were examined by particle size analysis and zeta potential measurements. Permeability assays were carried out on Caco-2 cell monolayers, the integrity of which was monitored by follow-up trans-epithelial electric resistance measurements (TEER). Cytocompatibility was tested by the MTT method, and an indirect dissolution test was performed, using DPPH antioxidant reagent. Two different SEDDS compositions were formulated from a standardized fenugreek dry extract at either the micro- or the nanoemulsion scale with sufficient stability, enhanced bioavailability of the compounds, and sustained release from HPMC capsules. Based on our results, a modern, non-toxic, cytocompatible fenugreek SEDDS formulation with high antioxidant capacity was developed in order to improve the permeability and bioavailability of all components.