Isolation of a potent anti-MRSA sesquiterpenoid quinone from Ulmus davidiana var. japonica

A highly potent anti-MRSA sesquiterpenoid has been isolated from Ulmus davidiana var. japonica, which has been traditionally used to treat infectious diseases in Korea. This naturally occurring antibiotic was identified as mansonone F (1). This compound has been found to be highly active specifically against MRSA and showed an MIC range of 0.39-3.13 microg/ml which is comparable to that of vancomycin.     

Untersuchung der Wackenroderschen Reaktion mit Hilfe der radiopapierchromatographischen Methode

Zusammenfassung Es wird beschrieben, wie man unter Anwendung von radioaktiven Stoffen kinetische Untersuchungen an der Wackenroderschen Reaktion durchführen kann. Dabei geht man nach einer papierchromatographischen Methode zur Trennung von Polythionsäuren vor, indem man durch laufende Probenentnahme während des Reaktionsablaufes die jeweilige Zusammensetzung der Wackenroderschen Flüssigkeit festhält. Die auf diese Weise gewonnenen Papierchromatogramme werden durch einen Radiopapierchromatographen ausgewertet. Die Verfolgung der einzelnen Stadien dieses Prozesses ist nur möglich, weil es sich bei der Wackenroderschen Reaktion hauptsächlich um langsame Vorgänge nach Art der Verseifungsprozesse handelt und dürfte daher mit Erfolg auf analoge Systeme zu übertragen sein.     

Interpretation of contact angle measurements on two different fluoropolymers for the determination of solid surface tension

Contact angle measurements with a large number of liquids on the semi-fluorinated acryl polymer EGC-1700 films are reported. The surface tension was determined to be gammasv=13.84 mJ/m2 from contact angles of octamethylcyclotetrasiloxane (OMCTS) and decamethylcyclopentasiloxane (DMCPS). Inertness of these two liquids makes them ideal for determination of surface tension of low-energy fluoropolymers. On the other hand, contact angles of many other liquids deviated somewhat from a smooth contact angle pattern that represents the EGC-1700 surface tension. It is argued that noninertness of the molecules of these liquids gives rise to specific interactions with the polymer film, causing the deviations. Furthermore, contact angles of a series of n-alkanes (n-hexane to n-hexadecane) showed systematic deviations from this curve, similar to the trend observed for n-alkanes/Teflon AF 1600 systems studied earlier. Adsorption of vapor of short-chain liquids onto the polymer film caused their contact angles to fall above the gammasv=13.84 mJ/m2 curve, and a parallel alignment of molecules of the long-chain n-alkanes in the vicinity of the solid was the explanation for the deviation of their contact angles below it. It is found that vapor adsorption effect is more significant in the case of Teflon AF 1600, while the alignment of liquid molecules close to the surface is more pronounced for EGC-1700.     

Analyse von Mononitrobenzoes?uren

Ohne Zusammenfassung     

Gaschromatographischer Vergleich verschiedener Branntweine

Zusammenfassung Durch Direktinjektion von 5–20 l verschiedener Branntweine wurden auf gaschromatographischen Trennsäulen in Verbindung mit Flammenionisationsdetektoren die Verbindungen Acetaldehyd, Essigsäure-methylester, Essigsäure-äthylester, Methanol, Butanol-2, Propanol-1, 2-Methylpropanol-1, Butanol-1, 2-Methyl-butanol-1, 3-Methyl-butanol-1 und Hexanol-1 aufgetrennt und quantitativ bestimmt. Vergleiche der Analysenzahlen zeigen, daß sich die Branntweingruppen Obstbrände, Weinbrände und Getreidebrände deutlich voneinander abgrenzen und darüber hinaus z.B. zwischen Cognacs und Weinbränden bzw. zwischen schottischen, amerikanischen und kanadischen Whiskies unterschieden werden kann.

---

Summary By direct injection of 5–20 l of various spirits the following compounds can be separated and determined on gas-chromatographic columns using flame-ionization detectors: acetaldehyde, methyl acetate, ethyl acetate, methanol, butanol-2, propanol-1, 2-methyl-propanol-1, butanol-1, 2-methyl-butanol-1, 3-methyl-butanol-1 and hexanol-1. A comparison of the analytical results reveals distinct differences between spirits from fruit, wine and grain. Moreover, different analytical results are obtained for cognacs and (German) brandies, and for Scotch, American and Canadian whiskies.

     

Determination of oxidized, reduced and protein-bound glutathione in eye lenses by high-performance liquid chromatography and electrochemical detection.

A method for the detection of oxidized, reduced and protein-bound glutathione in eye lenses has been developed. Homogenized lens samples are deproteinated with acetonitrile and perchloric acid. Protein-bound glutathione is reduced by 1,4-dithiothreitol. Separation of the different forms of glutathione and dithiothreitol is performed by ion-pair reversed-phase high-performance liquid chromatography with sodium octylsulphate as the ion-pairing agent. The compounds are detected amperometrically using on-line-generated bromine, which oxidizes thiols and disulphides. In this way two samples can be analysed in triplicate in a single day. The lower detection limits are 80 and 48 nmol per gram wet lens for reduced and oxidized glutathione, respectively. The amounts of free reduced and protein-bound glutathione in calf lenses, determined with this method, are 6.8 +/- 0.4 and 0.96 +/- 0.03 mumol per gram wet lens, respectively. That of oxidized glutathione is less than 0.048 mumol per gram wet lens.     

A molecular orbital study of the rotation about the C-C bond in 1,3-butadiene

The geometry and energy of 1,3-butadiene have been calculated using the 6-311G** basis set as a function of the CCCC dihedral angle-0 ° (trans), 30 °, 60 °, 75 °, 90 °, 120 °, 135 °, 150 °, 165 ° and 180 ° (cis)-assuming that the vinyl groups remain planar. Potential minima are located at 0 ° and 141.4 °, with the trans structure more stable than the gauche by 13.2 kJ mol^–1. Potential maxima are located at 76.7 °, giving a barrier height of 25.4 kJ mol^–1 relative to the trans structure, and at 180 ° giving a barrier height of 3.0 kJ mol^–1 relative to the 141.4 °-gauche structure. Using the 6-31G* basis set the inclusion of electron correlation, accounting for about 52% of the correlation energy, was found to produce no significant change in the shape of the potential energy curve. The magnitude of the expectation energy differences is such that both barriers with respect to the 14l.4 °-gauche maximum structure can be categorized unequivocally as attractive-dominant, whereas the values for the energy barrier with respect to the trans structure, although characteristic of a repulsive-dominant barrier at the 6–311G** level, are sufficiently small that higher level calculations might give the opposite result. Analysis of V _nn for the conversion reactions cis 150 °-gauche, trans 60 °-gauche, and trans 90 °-gauche in terms of the individual contributions from the various internuclear interactions shows that nonbonded interactions are important, not only in initiating the destabilization of the crowded cis structure, but also through-out the entire range of CCCC dihedral angles, 0 ° to 180 °.     

Surface enhanced Raman spectra of benzotriazole adsorbed on a copper electrode

The surface enhanced Raman spectrum of benzotriazole (BTAH) adsorbed on a copper electrode has been studied as a function of the potential applied to the electrode. The effect of pH and of the type of halide in the electrolyte solution has also been investigated. The presence of some complexes involving Cu(I), benzotriazole or benzotriazolate (BTA^-) and the halide has been characterized. The protective film formed on copper surface, in the presence of benzotriazole, has been identified as cuprous benzotriazolate [Cu(I)BTA].     

Membrane structure and its correlation with membrane permeability

Methods for the investigation of pore and molecular structure of synthetic membranes are reviewed. Membranes are classified as coarse-porous, fine-porous, and solution-diffusion membranes, on one hand; and homogeneous, asymmetric, and composite on the other, Pore structure of synthetic membranes can be elucidated in detail only by electron and raster electron microscopic investigations. Inspection of molecular structure requires diversely specific test probes such as low-energy neutron scattering and/or diffraction, and gas sorption and permeability measurements, as well as thermodynamic and thermomechanical analysis. Other methods used to elucidate pore and molecular structure of synthetic membranes are discussed and, concurrently, membrane structure is correlated with membrane permeability.