Investigation of semi-thin cryosections of lichens by laser microprobe mass spectrometry

The application of the laser microprobe mass spectrometry to the in-situ characterization of organic aromatic constituents in cryosections of microlichens is described. The samples were photographed before and after microprobe measurement by fluorescence microscopy or transmission electron microscopy to obtain more detailed information on the histological distribution of the compounds examined within the biological structures. This new technology has major advantages for integrated study of the morphology, anatomy and chemistry of plants.     

A new approach to canonical orthonormalisation

The canonical orthornormalisation procedure is derived through an integral equation with a finite rank kernel. Its optimal properties in connection with the problem of approximate linear dependence are established.     

Low-temperature dielectric losses of hydrocarbon media containing polar additives

Polypropylene films and other hydrocarbon media containing various dipolar additives were studied mainly between 4.2 and 105 K, and at 1.2 kHz. Five di     

Photochemistry of Biliverdin IX δ as a model for the study of the photoproducts from natural biliverdin IXγ (pterobilin)

The configurations of biliverdin-IX_γ and -IX_δ dimethyl esters 1 and 2 in solutions, have been studied using Nuclear-Overhauser-Effect (NOE) experiments. Irradiation (500-700 nm) of biliverdin IXδ gave syn-Z → anti-E isomerization of the central methine bridge and in aerated polar solutions, four new cyclized pigments were isolated for which structures 3, 4, 5 and 6 are proposed. Neobiliverdin IXδ 3 is also formed in degassed solution (Φ=4.10^?5) but pigments 4, 5 and 6 arise from photo-oxidation with O₂. Biliverdin IXδ appears to be a good model for the study of photo-reactions occurring on the vinyl groups of the natural biliverdin IXγ (pterobilin).     

Mise en evidence de plusieurs processus d'échange intramoléculaire dans les iodures de bis(méthyl thio)-1,1 dialkyl iminio-3 propène substitués ou non en 2 et 3

A variable temperature study of iminium salts is carried out. Several hindered rotations are observed around C? N and C? C bonds. Structural information is discussed.     

Azobenzene polymer stabilized ferroelectric liquid crystals: simultaneous photopolymerization and photoalignment

A single linearly polarized irradiation was used to initiate cationic photopolymerization of an azobenzene-containing diepoxide monomer dissolved in a ferroelectric liquid crystal (FLC) and, at the same time, to induce fast trans-cis-trans photoisomerization cycles for the azobenzene chromophore which leads to a bulk alignment of the FLC in the absence of surface orientation layers. The spectral output of the light source is required to have separate UV and visible wavelengths, which allow for simultaneous photopolymerization of the monomer and photoalignment of the chromophore. Photopolymerization was allowed to take place in different phases of the FLC to reveal the effects on the FLC photoalignment; the interaction between the anisotropic azobenzene polymer network and the FLC host was also investigated using polarizing UV-Vis spectroscopy.     

Simultaneous monitoring of monoamines,amino acids,nucleotides and neuropeptides by liquid chromatography‐tandem mass spectrometry and its application to neurosecretion in bovine chromaffin cells

The primary functions of adrenal medullary chromaffin cells are the synthesis and storage in their chromaffin vesicles of the catecholamines noradrenaline (NA) and adrenaline (AD), and their subsequent release into the bloodstream by Ca²⁺‐dependent exocytosis under conditions of fear or stress (fight or flight response). Several monoamines, nucleotides and opiates, such as leucine‐enkephalin (LENK) and methionine‐enkephalin (MENK), are also co‐stored and co‐released with the catecholamines. However, other neurotransmitters have not been studied in depth. Here, we present a novel high‐resolution liquid chromatography‐tandem mass spectrometry approach for the simultaneous monitoring of 14 compounds stored and released in bovine chromaffin cells (BCCs). We validated the analytical method according to the recommendations of the EMA and FDA by testing matrix effect, selectivity, sensitivity, precision, accuracy, stability and carry‐over. After testing on six batches of BCCs from different cultures, the method enabled simultaneous quantitative determination of monoamines (AD, NA, dopamine, serotonin, 5‐hydroxyindoleacetic acid, histamine and metanephrine), amino acids (L‐glutamic acid, γ‐aminobutyric acid), nucleotides (adenosine 5′‐diphosphate, adenosine 5′‐monophosphate, cyclic adenosine 5′‐monophosphate) and neuropeptides (LENK and MENK) in the intracellular content, basal secretion and acetylcholine induced secretion of BBCs. The high‐resolution approach used here enabled us to determine the levels of 14 compounds in the same BCC batch in only 16 min. This novel approach will make it possible to study the regulatory mechanisms of Ca²⁺ signaling, exocytosis and endocytosis using different neurotrophic factors and/or secretagogues as stimuli in primary BCC cultures. Our method is actually being applied to human plasma samples of different therapeutic areas where sympathoadrenal axis is involved in stress situations such as Alzheimer's disease, migraine or cirrhosis, to improve diagnosis and clinical practice. Copyright © 2016 John Wiley & Sons, Ltd.     

Marine natural products

This review covers the literature published in 2006 for marine natural products, with 758 citations (534 for the period January to December 2006) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, cnidaria, bryozoans, molluscs, tunicates and echinoderms. The emphasis is on new compounds (779 for 2006), together with their relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.     

BINOL-derived phosphoramidites in asymmetric hydrogenation: can the presence of a functionality in the amino group influence the catalytic outcome?

In discovering the remarkable catalytic properties of BINOL-derived phosphoramidites (binoP-NR(2)), Dutch researchers recently achieved a long-awaited breakthrough in asymmetric catalysis. For the first time, easily accessible monodentate chiral P(III) ligands turned out to provide high enantioselectivities when used in rhodium-catalysed olefin hydrogenation. The simplest ligand representative of this family is MonoPhos, which can be made straightforwardly from BINOL and hexamethylphosphorous triamide. Since the first publication dealing with such catalysts (J. Am. Chem. Soc., 2000), a variety of binoP-NRR' ligands have been reported in which the amino group bears a functional substituent or a stereogenic centre. This critical review examines the impact of the presence of such a functionality in the amino group on catalytic olefin hydrogenation reactions.