Introduction of A new Selective Oxidation Procedure Into Carbohydrate Chemistry - An Efficient Conversion of D-Galactose Into L-Fucose

Abstract

L-Fucose is widely spread in natural products. Due to its occurrence in glycoconjugates of blood-group substances, in milk oligosacchraides and other biologically important carbohydrates, this 6-deoxyhexose is of particular interest for oligosaccharide syntheses.     

AGSE: A Novel Grape Seed Extract Enriched for PP2A Activating Flavonoids That Combats Oxidative Stress and Promotes Skin Health

Environmental stimuli attack the skin daily resulting in the generation of reactive oxygen species (ROS) and inflammation. One pathway that regulates oxidative stress in skin involves Protein Phosphatase 2A (PP2A), a phosphatase which has been previously linked to Alzheimer’s Disease and aging. Oxidative stress decreases PP2A methylation in normal human dermal fibroblasts (NHDFs). Thus, we hypothesize agents that increase PP2A methylation and activity will promote skin health and combat aging. To discover novel inhibitors of PP2A demethylation activity, we screened a library of 32 natural botanical extracts. We discovered Grape Seed Extract (GSE), which has previously been reported to have several benefits for skin, to be the most potent PP2A demethylating extract. Via several fractionation and extraction steps we developed a novel grape seed extract called Activated Grape Seed Extract (AGSE), which is enriched for PP2A activating flavonoids that increase potency in preventing PP2A demethylation when compared to commercial GSE. We then determined that 1% AGSE and 1% commercial GSE exhibit distinct gene expression profiles when topically applied to a 3D human skin model. To begin to characterize AGSE’s activity, we investigated its antioxidant potential and demonstrate it reduces ROS levels in NHDFs and cell-free assays equal to or better than Vitamin C and E. Moreover, AGSE shows anti-inflammatory properties, dose-dependently inhibiting UVA, UVB and chemical-induced inflammation. These results demonstrate AGSE is a novel, multi-functional extract that modulates methylation levels of PP2A and supports the hypothesis of PP2A as a master regulator for oxidative stress signaling and aging in skin.     

High‐Output Polymer Screening: Exploiting Combinatorial Chemistry and Data Mining Tools in Catalyst and Polymer Development

High‐output polymer screening (HOPS) combines automated polymerization with online reaction monitoring, rapid polymer characterization and novel fingerprint technology useful in polymer preparation as well as polymer processing and polymer additive development. Originally, HOPS was introduced to develop polymerization catalysts and polyolefin materials more effectively. In comparison to conventional high‐throughput screening, focusing on ultrahigh speed of catalyst screening using arrays of miniaturized reactors, output‐oriented, process‐relevant HOPS is aiming at generating and exploiting high information density (useful information/experiment). Catalyst systems for olefin polymerization are evaluated in automated workstations with multiparallel as well as semi‐ and fully automated, upgraded lab reactors. Automated polymerizations under standardized conditions afford large families of well‐characterized polymers which serve as calibration samples for data analysis. Data analysis, using multivariate calibration, is the key to basic correlations between spectroscopic information and catalyst and polymer properties as well as reaction parameters and processing conditions. IR spectroscopic fingerprints are used to measure chemical copolymer composition, density, molecular weight as well as thermal and even mechanical properties. This fingerprint technology can be applied in online quality control and facilitates transfer from lab results into pilot and production plants. Fingerprint methods are important components of rapid online analysis and can reduce the need for time‐ and money‐consuming polymer testing.

Fingerprint technology combines spectroscopic analysis by means of “cheap” spectrometers with multivariate calibration.     

Structural influence on the 2D-conductivity of thin Au films

Thin gold films (60Å–500Å) are prepared simultaneously onto carbon coated quartz- and NaCl-crystals at different substrate temperatures (5 KT300 K) in uhv. For the Au-films condensed onto the quartz substrates the temperature dependence of the electrical resistivity is measured between 1.7 K and 300 K in situ. The corresponding Au-films condensed onto NaCl are removed and investigated in an EM. The observed hole and channel structures are related to the 2D-conductivity behavior.Dedicated to B. Mühlschlegel on the occasion of his 60th birthday     

Imaging and differentiation of mouse embryo tissues by ToF-SIMS

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) equipped with a gold ion gun was used to image mouse embryo sections and differentiate tissue types (brain, spinal cord, skull, rib, heart and liver). Embryos were paraffin-embedded and then deparaffinized. The robustness and repeatability of the method was determined by analyzing ten tissue slices from three different embryos over a period of several weeks. Using principal component analysis (PCA) to reduce the spectral data generated by ToF-SIMS, histopathologically identified tissue types of the mouse embryos can be differentiated based on the characteristic differences in their mass spectra. These results demonstrate the ability of ToF-SIMS to determine subtle chemical differences even in fixed histological specimens.     

Ion chromatographic determination of oxalate in plasma: correlation study with an enzymatic method

An ion chromatographic (IC) method for the determination of oxalate in plasma was developed. The method exploits a rapid and simple sample preparation step that substantially reduces the plasma chloride level to facilitate the oxalate determination. The chloride is removed as silver chloride by using a cation-exchange resin in the silver cation form. The dependence on chloride concentration and pH was evaluated. The oxalate recovery in plasma samples was found to be 93 ± 18% (n=4 trials) according to a standard addition study. A comparison of the IC method with an enzymatic method indicated that both methods measure the same oxalate concentration over the range examined, 5–300 μM. Furthermore, the comparison involved a correlation study that allowed cross-validation of the two methods, suggesting that neither is adversely affected by interferences. The detection limit of the IC method was 0.5 μM or 4.4 ng oxalate.     

Four-arm oligonucleotide Ni(II)-cyclam-centered complexes as precursors for the generation of supramolecular periodic assemblies

The development of a multiarm metal-centered DNA building block as a precursor for the construction of supramolecular assemblies has relied upon the preparation of a Ni(II)-1,4,8,11-tetrazacyclotetradecane ligand (cyclam) functionalized with four linkers. This complex can be incorporated into a support-bound DNA sequence and the remaining three linkers can then be elongated by DNA synthesis. The result is a Ni(II)-cyclam complex tethering four 20-mer DNA strands. This building block, designed to be tetrahedral in nature, can in principle be used to form tetrahedral assemblies. These assemblies can be designed to be of known size and composition or permitted to grow into complexes of essentially infinite size, ideally the macroscopic version of a crystal.     

Fast, easy, solvent-free, microwave-promoted Michael addition of anilines to α,β-unsaturated alkenes: synthesis of N-aryl functionalized β-amino esters and acids

The rapid, simple, microwave-promoted synthesis of N-aryl functionalized β-amino esters using Michael addition reactions is presented. Reactions are performed neat at 200 °C for 20 min and are catalyzed by acetic acid. The esters can be easily hydrolyzed to the corresponding N-aryl functionalized β-amino acids.