RESUMO
Isofloridosides (1-O-alpha-D-galactopyranosylglycerol) and floridoside (2-O-alpha-D-galactopyranosylglycerol) were extracted from the red alga Porphyra umbilicalis (Linné) Kützing (Bangiales, Rhodophyta). Their separation was achieved by HPLC (NH(2) P50 column) after successive purification of the crude extract by ion-exchange chromatography and HPLC (Sugar-Pak TM1 column). 1D and 2D NMR spectroscopy experiments allowed to completely assign the (1)H and (13)C spectra of D-isofloridoside.
Assuntos
Galactosídeos/química , Glicerol/análogos & derivados , Isótopos de Carbono , Cromatografia Líquida de Alta Pressão , Glicerol/química , Espectroscopia de Ressonância Magnética , PrótonsRESUMO
The red alga Grateloupia doryphora Montagne (Howe) (Cryptonemiales, Halymeniaceae) was used as a model to investigate the effects of changes in seawater salinity on the intracellular low-molecular-weight organic compounds. Carbon-partitioning into major organic solutes was followed by 13C nuclear magnetic resonance (NMR) spectroscopy on living algae incubated in NaH13CO3-enriched seawater, and by high resolution 1H and 13C NMR experiments performed on 13C-enriched algal extracts. NMR and high performance liquid chromatography (HPLC) analyses both demonstrated that floridoside level was the most affected by changes in salinity: it rose under the hypersaline treatment and decreased under hyposaline one. Moreover, at low salinity, the high labeling of floridoside (45.3% 13C-enrichment for C1) together with its low concentrations both provided evidence of great increase in the de novo biosynthesis and turnover rate. Our experiments also demonstrated a high incorporation of photosynthetic carbon into amino acids, especially glutamate, under hypoosmotic conditions. On the other hand, isethionic acid and N-methyl-methionine sulfoxide were only partly labeled, which indicates they do not directly derive from carbon photoassimilation. In algae exposed to high salinity, elevated concentrations of floridoside coupled to a low labeling (9.4%) were observed. These results suggest that hyperosmotic conditions stimulated floridoside biosynthesis from endogen storage products rather than from carbon assimilation through photosynthesis.
Assuntos
Glicerol/análogos & derivados , Ressonância Magnética Nuclear Biomolecular/métodos , Rodófitas/metabolismo , Bicarbonato de Sódio/metabolismo , Aminoácidos/química , Aminoácidos/metabolismo , Isótopos de Carbono , Glicerol/metabolismo , Ácido Isetiônico/metabolismo , Ácido Láctico/metabolismo , Concentração Osmolar , Água do Mar , Bicarbonato de Sódio/química , Cloreto de Sódio/química , Sulfóxidos/química , Sulfóxidos/metabolismo , Equilíbrio Hidroeletrolítico/fisiologiaRESUMO
Floridoside (2-O-alpha-D-galactopyranosylglycerol) was extracted from the red marine alga Rhodymenia palmata, and purified by ion-exchange chromatography: 1D and 2D NMR spectroscopy experiments were used to unambiguously assign the complete 1H and 13C spectra.
Assuntos
Glicerol/química , Heptoses/química , Rodófitas/química , Isótopos de Carbono/química , Glicerol/análogos & derivados , Espectroscopia de Ressonância Magnética/métodos , Biologia Marinha , Análise Espectral/métodosRESUMO
By use of 1H and 13C NMR spectroscopy including 2D 1H,1H DQF-COSY/TOCSY and 1H,13C HMQC/HMBC experiments, the main water-soluble carbohydrate components extracted from leaves of Matricaria maritima were identified as oligofructans composed of a linear chain of (2-->1)-linked beta-D-fructofuranosyl residues specifying an inulin-type structure. Alpha-D-Glcp-(1-->2)-[beta-D-Fruf-(2-->1)-beta-D-Frucf]n-(2-->1)-beta-D-Fruf.
Assuntos
Inulina/análogos & derivados , Matricaria/metabolismo , Oligossacarídeos/química , Sequência de Carboidratos , Frutose/química , Inulina/análise , Inulina/química , Espectroscopia de Ressonância Magnética , Matricaria/química , Dados de Sequência Molecular , Estrutura Molecular , Oligossacarídeos/análise , Folhas de Planta/química , Água/químicaRESUMO
The distribution of water-soluble phosphodiesters (WSPDEs) visible by nuclear magnetic resonance (NMR) in some intact tissues of rainbow trout (Oncorhynchus mykiss walbaum) and in perchloric extracts after partial purification was examined by (31)P NMR spectroscopy. The compounds of interest were serine ethanolamine phosphate (SEP), threonine ethanolamine phosphate (TEP), glycerophosphorylcholine (GPC), and glycerophosphorylethanolamine (GPE). TEP and SEP were mostly accumulated in the heart and less accumulated in the kidney of intact trout. After the extraction procedure, two additional minor resonances were visible and identified as GPC and GPE. The liver of trout contained large amounts of GPE. Similar investigations were conducted by (31)P NMR on hearts and kidneys of two elasmobranchs (Scyliorhinus canicula, Raja clavata) and four teleosts (Anguilla anguilla, Sparus auratus, Dicentrarchus labrax, Scophtlhalmus maximus); comparison with the trout data showed striking interspecies differences in the identity of WSPDEs. All teleosts, except eel and turbot, accumulated predominantly TEP. However, in elasmobranchs, first GPC and then GPE were the major compounds. Whatever the studied species, the relative abundances in the heart and kidney were similar. In the last two decades, two hypotheses were proposed to explain the occurrence of high levels of cytosoluble phosphodiesters: these compounds may constitute an index of phospholipid catabolism or a protective mechanism through which phospholipid levels are kept high. To test them and elucidate the role of these compounds in membrane phospholipid regulation in fish, we investigated the effects of two physiological stresses, that is, seawater adaptation and induced myocardial ischemia, on trout cytosolic phosphodiester levels. A 32.5-min ischemic stress caused no effect on SEP and TEP levels. On the contrary, significant osmotic stress induced changes in the PDEs levels: 2 d after transfer from freshwater to seawater or from seawater to freshwater, both tissues displayed a transient decrease of TEP; however, a 2-d stay in seawater after transfer from freshwater caused a rise in SEP concentration, whereas a 2-d stay in freshwater after transfer decreased SEP level. In conclusion, our experiments suggest a relationship between the high levels of cytosoluble phosphodiesters observed in some fish tissues and resistance to stress.
Assuntos
Adaptação Fisiológica , Citosol/química , Peixes/metabolismo , Fosfosserina/análogos & derivados , Fosfotreonina/análogos & derivados , Estresse Fisiológico/metabolismo , Análise de Variância , Animais , Evolução Biológica , Glicerilfosforilcolina/química , Rim/química , Espectroscopia de Ressonância Magnética , Miocárdio/química , Fosfatidiletanolaminas/química , Fosfosserina/química , Fosfotreonina/química , Água do MarRESUMO
Treatment of [Fe2(mu-pdt)(CO)6] [pdt=S(CH2)3S] with dppe (Ph2PCH2CH2PPh2) in refluxing toluene affords the asymmetric complex [Fe2(mu-pdt)(CO)4(dppe)] (1). Protonation of 1 with HBF4-Et2O in CH2Cl2 gives at room temperature the mu-hydrido derivative [Fe2(mu-pdt)(CO)4(dppe)(mu-H)](BF4) (2). Monitoring the reaction by 1H, 31P, and 13C NMR at low temperature reveals unambiguously that the process of the protonation of 1 implies terminal hydride intermediates.
Assuntos
Materiais Biomiméticos/química , Materiais Biomiméticos/metabolismo , Hidrogenase/química , Proteínas Ferro-Enxofre/química , Prótons , Sítios de Ligação , Modelos Moleculares , Conformação Molecular , Estereoisomerismo , Temperatura , Água/químicaRESUMO
Treatment of [Fe(2)(micro-pdt)(CO)(6)] (pdt = S(CH(2))(3)S) with 1,10-phenanthroline (phen) in refluxing toluene affords the asymmetric complex [Fe(2)(micro-pdt)(CO)(4)(phen)] (1); the protonation of with HBF(4).OEt(2) in CD(2)Cl(2) at 203 K has been monitored by (1)H NMR.
Assuntos
Compostos Férricos/química , Hidrogenase/química , Proteínas Ferro-Enxofre/química , Ferro/química , Fenantrolinas/química , Compostos de Sulfidrila/química , Sítios de Ligação , Catálise , Cristalografia por Raios X , Indicadores e ReagentesRESUMO
Adsorption isotherms of 2,5-dimethylpyridine (2,5-DMP) on Aerosil 200 silica from water-2,5-DMP binary mixtures are known to exhibit special features indicative of surface phase transitions in the adsorbed layer. We have made similar observations on another substituted pyridine, 2,4,6-trimethylpyridine (2,4,6-TMP). By using 1D and 2D NMR spectroscopy, we investigated adsorbed layers on silica in suspension in water/substituted-pyridine mixtures and demonstrated the existence of adsorbed species specific signals. Comparison of signals with those displayed on NMR spectra of liquid binary mixtures under various pH conditions rules out adsorption via interaction of the surface silanol group and the lone electron pair of the nitrogen atom. A mechanism of adsorption through the interaction of surface siloxane oxygen and the aromatic pi-system is proposed; it is consistent with both thermodynamic measurements and stacking of substituted pyridines within the adsorbed layer.