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The electrochemical initiated heterocoupling of 3-methylcatechol and n-hexylamine was investigated. The oxidation of 3-methylcatechol was performed in an electrochemical flow cell with glassy carbon as the working electrode. As a result, the two-electron, two-proton oxidised chinone intermediate undergoes a C-N coupling reaction in the presence of an amine (Michael addition). This mono coupling product can undergo a second two-electron, two-proton oxidation depending on acidic or basic conditions and substrate ratios. This flow cell was coupled on-line with electrospray ionisation mass spectrometry to identify the possible coupling products. Higher substrate concentrations were performed off-line as first scale-up experiments in a two-step procedure. [ABSTRACT FROM AUTHOR]

Flavonols, a class of flavonoids, are jointly responsible for antioxidant activities as free radical acceptors in flowers, fruits and vegetables. Due to their electroactive behaviour, the oxidation of chrysin, flavonol, kaempferol, morin, quercetin and myricetin in methanol was performed in an electrochemical flow cell with glassy carbon as the working electrode. This flow cell was coupled online with electrospray ionisation mass spectrometry to identify the possible oxidation products. Based on these experiments, it was concluded that when certain structural requirement are present, the initial electrode reaction of flavonols involves an electron delivery electrochemical step followed by a chemical step via methanol addition. The redox activity of the selected species explains the number of observed multiple methoxylation. Moreover, we identified a second two-electron, two-proton oxidation of the formed oxidation products of quercetin and myricetin for the first time. [ABSTRACT FROM AUTHOR]

The polysaccharide laminarin (β-1,3-glucan) is used as a long-term carbon storage compound in brown algae. This chemical storage form of carbon enables perennial brown algae in seasonally fluctuating ecosystems to uncouple growth from photosynthesis, i.e., most of these plants grow as seasonal anticipators in winter based on remobilization of laminarin, while in summer, growth typically ceased to fill up the storage pool. Because of this high ecological relevance, a reliable and precise method for determination and quantification of laminarin is needed. Therefore, a simple, efficient, cold water extraction method coupled to a new quantitative liquid chromatography-mass spectrometrical method (LC-MS) was developed. Laminarin was determined in 9 out of 12 brown algal species, and its expected typical molar mass distribution of 2000-7000 Da was confirmed. Furthermore, laminarin consisted of a complex mixture of different chemical forms, since 15 chemical laminarin species with distinct molecular weights were measured in 9 species of brown algae. Differences in chain length and number of laminarin species seem to be species specific and hence may indicate some chemotaxonomic value. Laminarin concentrations in the algal tissues ranged from 0.03 to 0.86 % dry weight (DW). The direct chemical characterization and quantification of laminarin by LC-MS represents a powerful method to verify the biochemical and ecological importance of laminarin for brown algae. [ABSTRACT FROM AUTHOR]

Flavonols, a class of flavonoids, are present in flowers, fruits and vegetables. They are jointly responsible for antioxidant activity as free radical acceptors. The redox behaviour of myricetin, quercetin, isorhamnetin, fisetin, morin and kaempferol is investigated using cyclic and differential pulse voltammetry. Quantum chemical calculations of proton affinities and electron transfer enthalpies were performed to identify possible reactive sites and radical species to compare them with measured oxidation potentials of the flavonols. Regarding to their chemical structure, these flavonols showed an oxidation order: myricetin > quercetin > isorhamnetin > fisetin > morin > kaempferol. [ABSTRACT FROM AUTHOR]

Photorespiratory 2-phosphoglycolate (2PG) metabolism is essential for photosynthesis in higher plants but thought to be superfluous in cyanobacteria because of their ability to concentrate CO[sub2] internally and thereby inhibit photorespiration. Here, we show that 3 routes for 2PG metabolism are present in the model cyanobacterium Synechocystis sp. strain PCC 6803. In addition to the photorespiratory C2 cycle characterized in plants, this cyanobacterium also possesses the bacterial glycerate pathway and is able to completely decarboxylate glyoxylate via oxalate. A triple mutant with defects in all 3 routes of 2PG metabolism exhibited a high-C02-requiring (HCR) phenotype. All these catabolic routes start with glyoxylate, which can be synthesized by 2 different forms of glycotate dehydrogenase (GIcD). Mutants defective in one or both GIcD proteins accumulated glycolate under high CO[sub2] level and the double mutant ΔgIcD1/ΔgIcD2 was unable to grow under low CO[sub2]. The HCR phenotype of both the double and the triple mutant could not be attributed to a significantly reduced affinity to CO[sub2]. such as in other cyanobacterial HCR mutants defective in the C02-concentrating mechanism (CCM). These unexpected findings of an HCR phenotype in the presence of an active CCM indicate that 2PG metabolism is essential for the viability of all organisms that perform oxygenic photosynthesis, including cyanobacteria and C3 plants, at ambient CO[sub2] conditions. These data and phylogenetic analyses suggest cyanobacteria as the evolutionary origin not only of oxygenic photosynthesis but also of an ancient photorespiratory 2PG metabolism. [ABSTRACT FROM AUTHOR]

Abstract: The use of ionic liquid–polymer in supported ultrafiltration membrane in vacuum pervaporation has been verified. The ultrafiltration membranes were impregnated by two ionic liquids (1-ethenyl-3-ethyl-imidazolium hexafluorophosphate and tetrapropylammonium tetracyano-borate) and polydimethylsiloxane. These new and very stable supported ionic liquid–polymer membranes were used for separation of ternary mixtures butan-1-ol–acetone–water by vacuum pervaporation. In comparison with polydimethylsiloxane membranes, the average enrichment factor of butan-1-ol increased in both cases. This higher selectivity shows a good potential for improving pervaporation separation process. [Copyright &y& Elsevier]

A fundamental electrochemical study of several highly diluted ionic liquids (ILs) at the interface between two immiscible electrolyte solutions (ITIES) is reported to evaluate the electrochemical and the solvation properties of [BMIM]Cl, [BMIM]BF 4 , [BMIM]OTf, [EMIM]Br and [AMIM]Cl. The interface is formed between a hydrophilic electrolyte dissolved in water and a hydrophobic electrolyte dissolved in an organic solvent, here 1,2-dichloroethane (DCE). The transfer of the highly diluted ionic species from the water phase into the organic phase occurs when an electrical potential difference is applied across the interface. Standard Gibbs energy of transfer, the relative hydrophilicity/hydrophobicity and transfer coefficients across the interface of the selected ILs are determined by cyclic voltammetry at large ITIES. [ABSTRACT FROM AUTHOR]

The oceanic N2-fixing cyanobacterium Trichodesmium spp. form extensive surface blooms and contribute significantly to marine carbon and nitrogen cycles in the oligotrophic subtropical and tropical oceans. Trichodesmium grows in salinities from 27 to 43 parts per thousand (ppt), yet its salt acclimation strategy remains enigmatic because the genome of Trichodesmiumerythraeum strain IMS101 lacks all genes for the biosynthesis of any known compatible solute. Using NMR and liquid chromatography coupled to mass spectroscopy, we identified the main compatible solute in T. erythraeum strain IMS101 as the quaternary ammonium compound N,N,N-trimethyl homoserine (or homoserine betaine) and elucidated its biosynthetic pathway. The identification of this compatible solute explains how Trichodesmium spp. can thrive in the marine system at varying salinities and provides further insight into the diversity of microbial salt acclimation. [ABSTRACT FROM AUTHOR]

Compatible solutes are small molecules that are involved in acclimation to various abiotic stresses, especially high salinity. Among the red algae, the main photosynthetic products floridoside and isofloridoside (galactosylglycerols) are known also to contribute to the osmotic acclimation of cells. However, the genes encoding (iso)floridoside biosynthetic enzymes are still unknown., To identify candidate genes, we examined the genome of the floridoside- and isofloridoside-accumulating extremophilic red alga Galdieria sulphuraria belonging to the Cyanidiales. We hypothesized that two candidate genes, Gasu_10960 and Gasu_26940, code for enzymes involved in floridoside and isofloridoside biosynthesis. These proteins comprise a sugar phosphate synthase and a sugar phosphate phosphatase domain. To verify their biochemical activity, both genes were in vitro translated into the entire proteins., The protein translation mixture containing Gasu_10960 synthesized small amounts of isofloridoside, whereas the Gasu_26940 translation mix also produced small amounts of floridoside. Moreover, the expression of Gasu_10960 in a salt-sensitive mutant of the cyanobacterium Synechocystis sp. PCC 6803 resulted in increased salt tolerance as a consequence of the presence of isofloridoside in the complemented cells., Thus, our experiments suggest that the Gasu_26940 and Gasu_10960 genes of G. sulphuraria encode the enzymatically active floridoside and isofloridoside phosphate synthase/phosphatase fusion proteins, respectively, crucial for salt acclimation. [ABSTRACT FROM AUTHOR]

The recently described red alga Tsunamia transpacifica (Stylonematophyceae) was previously isolated from plastic drift found at the pacific coast, but the natural habitat remains unknown. Here, we investigate ultrastructural details and the low molecular weight soluble carbohydrate composition to get further insight into the adaptation to this uncommon habitat. By means of high pressure freeze fixation, followed by freeze substitution, we could detect an up to 2-µm-thick cell wall surrounded by a distinct layer of extracellular polymeric substances (EPS), likely responsible for the adhering capacities of Tsunamia. The central position of the nucleus and multilobed parietal chloroplast, already observed by light microscopy, could be confirmed. The ultrastructure revealed large electron-dense bodies (EB) in the central cytoplasm, likely resembling degradation products of the chloroplast. Interestingly, these structures contained phosphorous and cobalt, and iron was found in smaller rounded electron-dense bodies by electron energy loss spectroscopy (EELS). Accumulation of these elements suggests a high biosorption activity of Tsunamia. Liquid chromatography-mass spectrometry (LC–MS) data showed the presence of two heterosides (floridoside and digeneaside) together with the polyol sorbitol, which are known as organic osmolytes and compatible solutes. Taken together, these are the first observations on ultrastructural details, element storage and accumulation of protective compounds are contributing to our understanding of the ultrastructural and osmotic solute basis for the ability of Tsunamia to thrive on plastic surfaces. [ABSTRACT FROM AUTHOR]

Pervaporation proved to be one of the best methods to remove solvents out of a solvent producing Clostridium acetobutylicum culture. By using an ionic liquid (IL)-polydimethylsiloxane (PDMS) ultrafiltration membrane (pore size 60 nm), we could guarantee high stability and selectivity during all measurements carried out at 37°C. Overall solvent productivity of fermentation connected with continuous product removal by pervaporation was 2.34 g l−1 h−1. The supported ionic liquid membrane (SILM) was impregnated with 15 wt% of a novel ionic liquid (tetrapropylammonium tetracyano-borate) and 85 wt% of polydimethylsiloxane. Pervaporation, accomplished with the optimized SILM, led to stable and efficient removal of the solvents butan-1-ol and acetone out of a C. acetobutylicum culture. By pervaporation through SILM, we removed more butan-1-ol than C. acetobutylicum was able to produce. Therefore, we added an extra dose of butan-1-ol to run fermentation on limiting values where the bacteria would still be able to survive its lethal concentration (15.82 g/l). After pervaporation was switched off, the bacteria died from high concentration of butan-1-ol, which they produced. [ABSTRACT FROM AUTHOR]

Highlights • A hypolepidemic drug atorvastatin (ATO) is taken up and metabolized by mussels. • ATO exposure leads to elevated basal metabolic rate and depletion of energy reserves in mussels. • Lipid content and mRNA expression of key fatty acid metabolism enzymes are suppressed by ATO. • Xenobiotic efflux through P-glycoprotein and membrane diffusion is suppressed by ATO. • ATO can act as metabolic disruptor and chemosensitizer in mussels. Abstract Biologically active compounds from pharmaceuticals cause concern due to their common occurrence in water and sediments of urbanized coasts and potential threat to marine organisms. Atorvastatin (ATO), a globally prescribed drug, is environmentally stable and bioavailable to marine organisms; however, the physiological and toxic effects of this drug on ecologically important coastal species are yet to be elucidated. We studied the effect of ATO (˜1.2 μg L−1) on bioenergetics (including whole-organism and mitochondrial respiration, as well as tissue energy reserves and mRNA expression of genes involved in mitochondrial biogenesis and fatty acid metabolism in the gills and the digestive gland) of a keystone bivalve Mytulis edulis (the blue mussel) from the Baltic Sea. Xenobiotic detoxification systems including activity and mRNA expression of P-glycoprotein, and Phase I and II biotransformation enzymes (cytochrome P450 monooxygenase CYP1A and glutathione transferase, GST) were also assessed in the gill and digestive gland of the mussels. Exposure to ATO caused rapid uptake and biotransformation of the drug by the mussels. Standard metabolic rate of ATO-exposed mussels increased by 56% indicating higher maintenance costs, yet no changes were detected in the respiratory capacity of isolated mitochondria. ATO exposure led to ˜60% decrease in the lysosomal membrane stability of hemocytes and ˜3-fold decrease in the whole-organism P-glycoprotein-driven and diffusional efflux of xenobiotics indicating altered membrane properties. The digestive gland was a major target of ATO toxicity in the mussels. Exposure of mussels to ATO led to depletion of lipid, carbohydrate and protein pools, and suppressed transcription of key enzymes involved in mitochondrial biogenesis (peroxisome proliferator-activated receptor gamma coactivator 1-alpha PGC-1α) and fatty acid metabolism (acetyl-CoA carboxylase and CYP4Y1) in the digestive gland. No bioenergetic disturbances were observed in the gills of ATO-exposed mussels, and elevated GST activity indicated enhanced ATO detoxification in this tissue. These data demonstrate that ATO can act as a metabolic disruptor and chemosensitizer in keystone marine bivalves and warrant further investigations of statins as emerging pollutants of concern in coastal marine ecosystems. [ABSTRACT FROM AUTHOR]

It was a big surprise to see crystals of an ionic liquid (IL) forming by sublimation at room temperature. ILs are generally accepted to have negligible vapour pressures at elevated temperatures, making their sublimation or distillation very difficult. ILs that sublime easily contain silylimidazolium-based cations. In order to establish the details of the unusual behaviour of this subclass of ILs, a combined spectroscopic, X-ray crystallographic, physicochemical and theoretical characterization was performed. The results are compared with those of other easily vaporizable compounds, like ammonium chloride and naphthalene. The single-crystal X-ray structure analysis of one of these compounds, N-methyl- N′-dimethyl(phenyl)silylimidazolium chloride (monoclinic, C2/ c), clearly shows the existence of isolated ions, demonstrating that the compound is an ionic liquid. [ABSTRACT FROM AUTHOR]

The occurrence of a photorespiratory 2-phosphoglycolate metabolism in cyanobacteria is not clear. In the genome of the cyanobacterium Synechocystis sp. strain PCC 6803, we have identified open reading frames encoding enzymes homologous to those forming the plant-like C2 cycle and the bacterial-type glycerate pathway. To study the route and importance of 2-phosphoglycolate metabolism, the identified genes were systematically inactivated by mutagenesis. With a few exceptions, most of these genes could be inactivated without leading to a high-CO2-requiring phenotype. Biochemical characterization of recombinant proteins verified that Synechocystis harbors an active serine hydroxymethyltransferase, and, contrary to higher plants, expresses a glycolate dehydrogenase instead of an oxidase to convert glycolate to glyoxylate. The mutation of this enzymatic step, located prior to the branching of phosphoglycolate metabolism into the plant-like C2 cycle and the bacterial- like glycerate pathway, resulted in glycolate accumulation and a growth depression already at high CO2. Similar growth inhibitions were found for a single mutant in the plant-type C2 cycle and more pronounced for a double mutant affected in both the C2 cycle and the glycerate pathway after cultivation at low CO2. These results suggested that cyanobacteria metabolize phosphoglycolate by the cooperative action of the C2 cycle and the glycerate pathway. When exposed to low CO2, glycine decarboxylase knockout mutants accumulated far more glycine and lysine than wild-type cells or mutants with inactivated glycerate pathway. This finding and the growth data imply a dominant, although not exclusive, role of the C2 route in cyanobacterial phosphoglycolate metabolism. [ABSTRACT FROM AUTHOR]

Abstract: l-1-Deoxy-1-fluoro-6-O-methyl-myo-inositol was epimerized by chloral/DCC in boiling 1,2-dichloroethane yielding d-1-O-cyclohexylcarbamoyl-2-deoxy-2-fluoro-3-O-methyl-5,6-O-[(R/S)-2,2,2-trichloroethylidene]-chiro-inositol. The latter and l-4-O-benzyl-3-O-cyclohexylcarbamoyl-5-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-muco-inositol, l-4-O-benzyl-3-O-cyclohexylcarbamoyl-1,2-O-ethylidene-5-O-methyl-muco-inositol, d-1-O-cyclohexylcarbamoyl-2-deoxy-5,6-O-ethylidene-2-fluoro-3-O-methyl-chiro-inositol, as well as d-5-O-benzyl-4-O-cyclohexylcarbamoyl-3-deoxy-3-(N,N′-dicyclohexylureido)-6-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-chiro-inositol were deprotected with boiling 57% aq hydrogen iodide. Ether, urethane and ethylidene acetal functions were simultaneously cleaved by the reagent, whereas the trichloroethylidene groups were still intact or were only removed in small quantities. Especially, the urea function of d-5-O-benzyl-4-O-cyclohexylcarbamoyl-3-deoxy-3-(N,N′-dicyclohexylureido)-6-O-methyl-1,2-O-(2,2,2-trichloroethylidene)-chiro-inositol was decomposed to a cyclohexylamino group. The hydrodechlorination of d-1-O-cyclohexylcarbamoyl-2-deoxy-2-fluoro-3-O-methyl-5,6-O-[(R/S)-2,2,2-trichloroethylidene]-chiro-inositol using Raney-Nickel yielded a mixture of the corresponding 5,6-O-ethylidene- and 5,6-O-chloroethylidene derivatives. The three synthetic steps—hydrodehalogenation, HI-deprotection and peracylation- were combined without purification of the intermediates. [Copyright &y& Elsevier]

This study is aimed at improving a protocol for measuring fatty acids in cattle hair with respect to sensitivity, repeatability, and speed to increase its applicability as a biomarker. For the investigation, 14 hair samples from German Holstein cows are used. Alternative methods for grinding the hair (mortar vs mill), lipid extraction (modified Folch vs kit extraction), and solvent evaporation before injection on a gas chromatograph (evaporated vs unevaporated extracts) are tested. Hair ground with a mill compared to that with a mortar has smaller particles and a higher concentration of total lipids after extraction (p < 0.02). The kit used for lipid extraction is faster, and the amount of extracted total lipids and individual fatty acids, especially C12:0, is increased (p = 0.001). The analysis of unevaporated methyl ester extracts using gas chromatography (GC) analysis yields 5.8 and 1.3 higher amounts of C10:0 and C12:0, respectively, than those of evaporated extracts (p < 0.001). According to the results, the protocol for determining fatty acids in cattle hair can be improved by grinding the hair with a mill, extraction of lipids with a kit, and direct loading of methyl ester extracts in a gas chromatograph. Practical Applications: The fatty acid profile of hair reflects the metabolic status of an animal for the previous 1–3 weeks, as these fatty acids are not influenced by diurnal and short‐term fluctuations. An improved protocol is developed that increases the throughput of fatty acid analysis and improves its applicability for practical use. For breeding and animal welfare, the analysis of cattle hair is possible for more efficient evaluation of the hair fatty acid profile as a robust biomarker in a larger animal population. [ABSTRACT FROM AUTHOR]