Combined mass spectrometric and chromatographic methods for in‐depth analysis of phenolic secondary metabolites in barley leaves

Structural analysis via HPLC‐ESI‐MSn, UPLC‐HESI‐MS/MS and NMR reported 152 phenolic secondary metabolites in spring barley seedlings (Hordeum vulgare L.). Flavonoids with various patterns of glycosylation and acylation, as well as hydroxycinnamic acid glycosides, esters and amides, were identified in methanolic extracts from leaves of nine varieties of barley originating from different regions of the world. Hordatines derivatives, flavones acylated directly on the aglycone, and hydroxyferulic acid derivatives deserve special attention. Preparative chromatography enabled characterization of a number of compounds at trace levels with the 6‐C‐[6″‐O‐glycosyl]‐glycosides and the 6‐C‐[2″,6″‐di‐O‐glycosides]‐glucoside structure of flavones. Derivatives of flavonols, quercetin and isorhamnetin were observed only in Syrian varieties. The ultra performance liquid chromatography profiles of UV‐absorbing secondary metabolites were used for chemotaxonomic comparison between nine varieties of barley from different climatic conditions. The hierarchical clustering of bred lines from the Fertile Crescent and European and American varieties indicates a great diversity of chemical phenotypes within barley species. Copyright © 2015 John Wiley & Sons, Ltd.     

Reduction of vibration due to change in mass configuration

The paper concerns the elimination of vibration due to changing the centre of gravity of a system. It is shown that the damping effect can be generated in an oscillating pendulum by a continuous motion of an auxiliary mass. A simple system in form of a variable length pendulum is considered. It is seen that if the pendulum length function is correctly chosen, the Coriolis force will cause additional damping effect in the system. The Floquet method is used to investigate the linear system stability. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Green Oxidation of Amines by a Novel Cold-Adapted Monoamine Oxidase MAO P3 from Psychrophilic Fungi Pseudogymnoascus sp. P3

The use of monoamine oxidases (MAOs) in amine oxidation is a great example of how biocatalysis can be applied in the agricultural or pharmaceutical industry and manufacturing of fine chemicals to make a shift from traditional chemical synthesis towards more sustainable green chemistry. This article reports the screening of fourteen Antarctic fungi strains for MAO activity and the discovery of a novel psychrozyme MAOP3 isolated from the Pseudogymnoascus sp. P3. The activity of the native enzyme was 1350 ± 10.5 U/L towards a primary (n-butylamine) amine, and 1470 ± 10.6 U/L towards a secondary (6,6-dimethyl-3-azabicyclohexane) amine. MAO P3 has the potential for applications in biotransformations due to its wide substrate specificity (aliphatic and cyclic amines, pyrrolidine derivatives). The psychrozyme operates at an optimal temperature of 30 °C, retains 75% of activity at 20 °C, and is rather thermolabile, which is beneficial for a reduction in the overall costs of a bioprocess and offers a convenient way of heat inactivation. The reported biocatalyst is the first psychrophilic MAO; its unique biochemical properties, substrate specificity, and effectiveness predispose MAO P3 for use in environmentally friendly, low-emission biotransformations.     

Overview of Popular Techniques of Raman Spectroscopy and Their Potential in the Study of Plant Tissues

Raman spectroscopy is one of the main analytical techniques used in optical metrology. It is a vibration, marker-free technique that provides insight into the structure and composition of tissues and cells at the molecular level. Raman spectroscopy is an outstanding material identification technique. It provides spatial information of vibrations from complex biological samples which renders it a very accurate tool for the analysis of highly complex plant tissues. Raman spectra can be used as a fingerprint tool for a very wide range of compounds. Raman spectroscopy enables all the polymers that build the cell walls of plants to be tracked simultaneously; it facilitates the analysis of both the molecular composition and the molecular structure of cell walls. Due to its high sensitivity to even minute structural changes, this method is used for comparative tests. The introduction of new and improved Raman techniques by scientists as well as the constant technological development of the apparatus has resulted in an increased importance of Raman spectroscopy in the discovery and defining of tissues and the processes taking place in them.     

Flexibility of a biotinylated ligand in artificial metalloenzymes based on streptavidin—an insight from molecular dynamics simulations with classical and ab initio force fields

In the field of enzymatic catalysis, creating activity from a non catalytic scaffold is a daunting task. Introduction of a catalytically active moiety within a protein scaffold offers an attractive means for the creation of artificial metalloenzymes. With this goal in mind, introduction of a biotinylated d⁶-piano-stool complex within streptavidin (SAV) affords enantioselective artificial transfer-hydrogenases for the reduction of prochiral ketones. Based on an X-ray crystal structure of a highly selective hybrid catalyst, displaying significant disorder around the biotinylated catalyst [η⁶-(p-cymene)Ru(Biot-p-L)Cl], we report on molecular dynamics simulations to shed light on the protein–cofactor interactions and contacts. The results of these simulations with classical force field indicate that the SAV-biotin and SAV-catalyst complexes are more stable than ligand-free SAV. The point mutations introduced did not affect significantly the overall behavior of SAV and, unexpectedly, the P64G substitution did not provide additional flexibility to the protein scaffold. The metal-cofactor proved to be conformationally flexible, and the S112K or P64G mutants proved to enhance this effect in the most pronounced way. The network of intermolecular hydrogen bonds is efficient at stabilizing the position of biotin, but much less at fixing the conformation of an extended biotinylated ligand. This leads to a relative conformational freedom of the metal-cofactor, and a poorly localized catalytic metal moiety. MD calculations with ab initio potential function suggest that the hydrogen bonds alone are not sufficient factors for full stabilization of the biotin. The hydrophobic biotin-binding pocket (and generally protein scaffold) maintains the hydrogen bonds between biotin and protein.     

Solubility and pKa of select pharmaceuticals in water,ethanol, and 1-octanol

Solubilities of six pharmaceuticals, namely nadolol, atenolol, bifonazole, nimesulide, estrone, mefenamic acid at constant pH, were measured over the range of temperature from (240 to 340) K in three important for drug solvents: water, ethanol, and 1-octanol using the dynamic method and spectroscopic UV–Vis method. Dissociation constants and corresponding pK_a values of the drugs were obtained with the Bates–Schwarzenbach method using UV–Vis Perkin–Elmer Lambda 35 Spectrophotometer at temperature 298.15 K in the buffer solutions. Our experimental pK_a values for nadolol, bifonazole, nimesulide, and mefenamic acid are 9.3, 5.85, 7.34, and 3.88, respectively. The basic thermal properties of pure drugs i.e. fusion and glass-transition temperatures, as well as the enthalpy of fusion and the molar heat capacity at the glass-transition (at constant pressure) have been measured using the differential scanning microcalorimetry technique (DSC). Molar volumes have been calculated with the Barton group contribution method. The experimental solubility results have been correlated by means of three commonly known G^E equations: the Wilson, NRTL, and UNIQUAC with the assumption that the systems studied here are simple eutectic mixtures. The activity coefficients of pharmaceuticals in saturated solutions in each correlated binary mixture were calculated from the experimental results. Prediction of solubility in water at T = 298.15 K was made by the group contribution method.     

Application of <Superscript>31</Superscript>P NMR for added polyphosphate determination in pork meat

Application of ³¹P NMR for qualitative and quantitative determination of added phosphorus compounds in meat samples is described. Furthermore, usefulness of the proposed method for monitoring of poly- and pyrophosphates hydrolysis in meat is discussed. Calibration curves based on the ³¹P resonance line areas were elaborated for Na₃P₃O₉, Na₅P₃O₁₀, Na₂H₂P₂O₇, and K₄P₂O₇ resulting in linearity (R ² = 0.9976, 0.9953, 0.9974, and 0.9524, respectively), detection limits (DL from 0.0018 mol L⁻¹ for Na₃P₃O₉ to 0.0070 mol L⁻¹ for K₄P₂O₇), and quantification limits (QL from 0.0060 mol L⁻¹ for Na₃P₃O₉ to 0.0234 mol L⁻¹ for K₄P₂O₇). The developed procedure was applied for laboratory prepared meat samples and compared with the standard UV-VIS method. The minimal sample pretreatment, obtained within-day precision (CV ≤ 2.0 %) and accuracy (as recovery ≥ 95 %) suggest ³¹P NMR as an alternative method of phosphorus determination in food analysis.     

Reversed-Phase Stepwise Gradient Thin-Layer Chromatography of 19 Test Dye Mixtures with a Single Void Volume of the Mobile Phase

JPC – Journal of Planar Chromatography – Modern TLC - Satisfactory separation of a test mixture of 19 dyes with a general elution problem was obtained by reversed-phase stepwise...