Glycosyl-nucleoside fluorinated amphiphiles as components of nanostructured hydrogels

The synthesis of two novel glycosyl-nucleoside fluorinated amphiphiles (GNFs) derived from the 2H,2H,3H,3H-perfluoro-undecanoyl hydrophobic chain is described. The GNF amphiphiles, which feature either β-d-glucopyranosyl or β-d-lactopyranosyl moieties linked to a thymine base via a 1,2,3 triazole linker, were prepared using a ‘double click’ chemistry route. Surface tension measurements, gelation properties, and TEM studies show that GNFs spontaneously assemble into supramolecular structures. Similarly to their hydrocarbon analogues (GNLs), the GNFs have unique gelation properties in water. A minimum hydrogelation concentration of 0.1% (w/w), was determined in the case of the β-d-glucopyranosyl derivative. Cell viability studies indicate that fluorocarbon GNF 5 was not toxic for human cells (Huh7), whereas hydrocarbon analogue GNL is toxic above 100 μm.     

μSR in UAs

UAs has the NaCl structure and undergoes a first order transition into a type I (single k) antiferromagnetic state at 123 K, followed by a second first order transition at 62 K into a type IA (double k) antiferromagnetic structure. μSR spectra of a powder sample were taken in zero and transverse fields up to 0.3 T. They cover the paramagnetic and the two antiferromagnetic states. The most significant features of our data are: i) a first increase of relaxation rate below T=180 K; ii) a sudden jump in both, relaxation rate and frequency shift at T=123 K, together with a small decrease in initial asymmetry (≈15%); iii) no μ⁺ spin rotation in zero field in the type I state; iv) an overlay, of 3 spectra in the type IA state. Two of these spectra show spin rotation in zero field. Their frequencies are clearly temperature dependent. In a transverse field of 5 and 10 mT the external field adds nearly fully to the internal field. Work supported in part by the Bundesministerium fur Forschung und Technologie, Federal Republic Germany.     

Studies of the out-of-plane emission of pions in symmetric heavy-ion collisions

Triple differential cross-sections of midrapidity pions from ²⁰⁹Bi+²⁰⁹Bi collisions were measured with the Kaon Spectrometer at SIS at incident energies of 400, 700 and 1000 AMeV. The azimuthal emission pattern of the pions has been investigated in dependence of beam energy and impact parameter. An enhanced emission of pions perpendicular to the reaction plane is observed. The strength of the anisotropy increases with beam energy and pion transverse momentum. In contrast to the nucleons the anisotropy varies only little with the impact parameter. No difference in the behaviour of positive and negative pions is observed.     

The probable conformation of substrates recognized by dipeptidyl-peptidase IV and some aspects of the catalytic mechanism derived from theoretical investigations

Summary By theoretical conformational investigations of substrates and nonsubstrates of the enzyme dipeptidyl-peptidase IV (DP IV) as well as dipeptide-esters using the ECEPP83 method we determined the structure of peptides recognized and cleaved by the enzyme. From a comparison of all possible structures for the substrates with conformations not possible in nonsubstrates we concluded that a single conformation explains substrate specificities of DP IV. This conformation is characterized by the following dihedral angles: {ie159-1}, {ie159-2}, {ie159-3}, {ie159-4}, and {ie159-5}. The conclusions were supported by comparisons of molecular electrostatic potentials calculated with the molecular graphics program HAMOG.     

Ueber einige Aenderungen der Lehmann'schen Methode zur Bestimmung von Zucker

Ohne Zusammenfassung     

Capillary electrophoresis and hollow fiber liquid-phase microextraction for the enantioselective determination of albendazole sulfoxide after biotransformation of albendazole by an endophytic fungus

Hollow fiber liquid-phase microextraction and CE were applied for the determination of albendazole sulfoxide (ASOX) enantiomers in liquid culture medium after a fungal biotransformation study. The analytes were extracted from 1 mL of liquid culture medium spiked with the internal standard (rac-hydroxychloroquine) and buffered with 0.50 mol/L phosphate buffer, pH 10. The analytes were extracted into 1-octanol impregnated in the pores of the hollow fiber, and into an acid acceptor solution inside the polypropylene hollow fiber. The electrophoretic separations were carried out in 0.05 mol/L tris(hydroxymethyl)aminomethane buffer, pH 9.3, containing 3.0% w/v sulfated-β-CD (S-β-CD) with a constant voltage of +15 kV and detection at 220 nm. The method was linear over the concentration range of 250-5000 ng/mL for each ASOX enantiomer. Within-day and between-day assay precision and accuracy for the analytes were studied at three concentration levels and the values of RSD% and relative error % were lower than 15%. The developed method was applied for the determination of ASOX after a biotransformation study employing the endophytic fungus Penicillium crustosum (VR4). This study showed that the endophytic fungus was able to metabolize the albendazole to ASOX enantioselectively. In addition, it was demonstrated that hollow fiber liquid-phase microextraction coupled to CE can be an excellent and environmentally friendly technique for the analysis of samples obtained in biotransformation studies.