170 research outputs found
Mass spectrometric evidence for the existence of oligomeric anthocyanins in grape skins
No full textStéphane Vidal, Emmanuelle Meudec, Véronique Cheynier, George Skouroumounis and Yoji Hayasak
Fractionation of grape anthocyanin classes using multilayer coil countercurrent chromatography with step gradient elution
No full textCopyright © 2004 American Chemical SocietyStéphane Vidal, Yoji Hayasaka, Emmanuelle Meudec, Véronique Cheynier, and George Skouroumouni
Analysis by High-Performance Liquid Chromatography Diode Array Detection Mass Spectrometry of Phenolic Compounds in Fruit of Eucalyptus globulus Cultivated in Algeria
No full textCorrespondance auteur: Meudec E. E-mail: [email protected] audienceA method based on high-performance liquid chromatography coupled with diode array detection and electrospray ionization mass spectrometry (HPLC-DAD-ESI-MS) following fractionation by chromatography on a Sephadex LH-20 column has been developed to determine the phenolic composition of fruit of Eucalyptus globulus growing in Algeria. The presence of 18 gallotannins, 26 ellagitannins, and 2 flavonols was established. Tentative identification is provided for these compounds on the basis of UV-visible spectra and mass spectrometry data. Most compounds described in this study have not previously detected in fruit of E. globulus. Moreover, this is the first report of methyl digalloyl diglucose, 3,30-O-dimethylellagic acid 4-O-â-glucopyranoside, ellagic acid hexose, methyl ellagic acid pentose, methyltetragalloylglucose, and valoneic acid isomers (sanguisorbic, flavogallic acid dilactone) in the genus Eucalyptus. Quantitatively, ellagic acid and its derivatives, including ellagitannins, are largely predominan
Interspecific variation in leaf litter tannins drives decomposition in a tropical rain forest of French Guiana
No full textEcology ISI Document Delivery No.: 621GL Times Cited: 26 Cited Reference Count: 74 Coq, Sylvain Souquet, Jean-Marc Meudec, Emmanuelle Cheynier, Veronique Hattenschwiler, Stephan Cnrs We thank Bruno Buatois, Raphaelle Leclerc, and Laurette Sonie for laboratory support, Marie-Madeleine Couteaux for her help in litter bag assemblage and helpful discussions, Anne-Marie Domenach and Damien Bonal for continuous local support in French Guiana, Sylvie Rapior and the staff of her laboratory for discussions on polyphenol chemistry and analyses, Mathieu Coulis for his help with tannin measurements, Tanya Handa and Christiane Gallet for stimulating discussion and useful comments on the manuscript, and Deborah A. Clark and an anonymous reviewer for thoughtful comments and suggestions for improving the manuscript. This research was funded through an ATIP research grant from CNRS (SDV) to S. Hattenschwiler. Ecological soc amer WashingtonInternational audienceTannins are believed to be particularly abundant in tropical tree foliage and are mainly associated with plant herbivore defense. Very little is known of the quantity, variation, and potential role of tannins in tropical leaf litter. Here we report on the interspecific variability of litter condensed tannin (CT) concentration among 16 co-occurring tropical rain forest tree species of French Guiana and explore the functional significance of variable litter CT concentration for litter decomposition. We compared some classical methods in the ecological literature to a method based on high-performance liquid chromatography (HPLC), coupled with CT degradation by phloroglucinolysis. The same litter was allowed to decompose in the field in the presence or absence of soil fauna. We found large interspecific differences in the average polymerization degree (2.7 to 21.3, for non-extractable CT) and concentration of litter CT (0-3.7% dry mass, for total CT) determined by HPLC, which did not correlate with Folin total phenolics but correlated reasonably well with acid butanol CT. The concentration and polymerization degree of HPLC-determined CT were the only variables of the multitude of measured initial litter quality parameters that explained a signi. cant amount of variation in litter mass loss among species, irrespective of animal presence. However, animal presence increased mean litter mass loss by a factor of 1.5, and the fauna effect on decomposition was best explained by a negative correlation with total HPLC CT and by a positive correlation with hemicellulose. Our results suggest that the commonly used acid butanol assay yields a reliable estimate of interspecific variation in CT concentration. However, the chemical structure of CTs, such as the polymerization degree, adds important information for the understanding of the functional role of CTs in litter decomposition. We conclude that the wide variation in structure and concentration of leaf litter CTs among tropical tree species is an important driver of decomposition in this nutrient-poor Amazonian rain forest
Characterization, stoichiometry, and stability of salivary protein-tannin complexes by ESI-MS and ESI-MS/MS
No full textAnal. Bioanal. Chem. ISI Document Delivery No.: 522RX Times Cited: 18 Cited Reference Count: 75 Canon, Francis Pate, Franck Meudec, Emmanuelle Marlin, Therese Cheynier, Veronique Giuliani, Alexandre Sarni-Manchado, Pascale French Agence Nationale de la Recherche (A.N.R.) [07-BLAN-0279] The authors thank Helene Boze and Claire Bouchut (UMR 1083 SPO) for their help in protein production and purification and MS experiments. We acknowledge synchrotron SOLEIL and thank all staff for assistance in using beamline DISCO. AG thanks Applied Biosystems (Les Ullis, France) for the loan of the IonCooler Guide. This work is supported by grant 07-BLAN-0279 from the French Agence Nationale de la Recherche (A.N.R.). Springer heidelberg HeidelbergInternational audienceNumerous protein-polyphenol interactions occur in biological and food domains particularly involving proline-rich proteins, which are representative of the intrinsically unstructured protein group (IUP). Noncovalent protein-ligand complexes are readily detected by electrospray ionization mass spectrometry (ESI-MS), which also gives access to ligand binding stoichiometry. Surprisingly, the study of interactions between polyphenolic molecules and proteins is still an area where ESI-MS has poorly benefited, whereas it has been extensively applied to the detection of noncovalent complexes. Electrospray ionization mass spectrometry has been applied to the detection and the characterization of the complexes formed between tannins and a human salivary proline-rich protein (PRP), namely IB5. The study of the complex stability was achieved by low-energy collision-induced dissociation (CID) measurements, which are commonly implemented using triple quadrupole, hybrid quadrupole time-of-flight, or ion trap instruments. Complexes composed of IB5 bound to a model polyphenol EgCG have been detected by ESI-MS and further analyzed by MS/MS. Mild ESI interface conditions allowed us to observe intact noncovalent PRP-tannin complexes with stoichiometries ranging from 1:1 to 1:5. Thus, ESI-MS shows its efficiency for (1) the study of PRP-tannin interactions, (2) the determination of stoichiometry, and (3) the study of complex stability. We were able to establish unambiguously both their stoichiometries and their overall subunit architecture via tandem mass spectrometry and solution disruption experiments. Our results prove that IB5.EgCG complexes are maintained intact in the gas phase
The impact of distillation process on the chemical composition and potential prebiotic activity of different oligosaccharidic fractions extracted from grape seeds
No full textThe study was designed to evaluate how the distillation process is able to affect the composition and bioactivity of oligosaccharides contained in the grape seeds. Different oligosaccharidic fractions have been extracted both before and after grape pomace distillation in order to valorize this by-product. A multistep solid-phase extraction approach (C-18 and carbograph cartridges) has been applied to purify and fractionate the oligosaccharidic compounds. Chemical characterization of the fractions was performed using a UPLC-ESI-MSn method. Complex oligosaccharides consist principally of neutral oligosaccharides rich in arabinose and glucose. Then, the oligosaccharides contained in the different fractions as potential functional ingredients with prebiotic activity toward well-known probiotic bacteria, such as Lactobacillus acidophilus and Lactobacillus plantarum, were evaluated. Data showed how, in some combination, oligosaccharidic fractions obtained may be considered a novel "functional ingredient" with potential prebiotic activity mainly towards L. acidophilus
Ordinary Ethics of Spiritual Work and Healing in St. Lucia, or Why Not to Use the Term <i>Obeah</i>
No full textThe purpose of this essay is to understand the language of spiritual work and healing in St. Lucia as well as the moral impregnation of the term obeah. This ethnographic study of ordinary ethics of obeah explores the significant gap between the designation and auto-legitimation of healers and spiritual workers. Because, in most cases, the term is not used by practitioners to identify their spiritual and healing practice, the author proposes to relocate the definition of obeah from its specific practices to its moral burden. This approach helps reevaluate the use of obeah in social science writings related to the St. Lucian context. Social scientists must be very attentive to not contribute to the othering of healing and spiritual practices and to consider their involvement in its construction.</jats:p
values estimated by the Savitzky–Golay first derivative
No full textInternational audienceRationale The calculation of centroids from profile mass spectra is one of the very first steps in the processing of mass spectra. The output is a signal and a m/z value. We focus on the accuracy of the prediction of the centroids' m/z values.Methods A calculation based on the Savizky-Golay algorithm was evaluated on an Orbitrap mass spectrum. Reference m/z values were identified manually. Experimental centroids were extracted (1) automatically using our algorithm or the MSconvert algorithm and (2) manually using the Xcalibur software from Thermo. The three series of experimental m/z values were compared with the reference m/z values.Results Our algorithm improved the determination of the m/z values compared with MSconvert. However, no improvement was observed over Xcalibur.Conclusions Our algorithm improved the automatic estimation of m/z values in the profile-to-centroid calculation. This is of importance when the goal is to determine raw compositions from the experimental m/z values. Nevertheless, the algorithms led to almost the same m/z values on a higher resolution mass spectrum
Complex carbohydrates of red wine : characterization of wine neutral oligosaccharides by hydrophilic interaction liquid chromatography coupled to ESI-MS
No full textCharacterization of wine neutral oligosaccharides by Hydrophilic Interaction Liquid Chromatography coupled to ESI-MS. 9. Symposium In Vino Analytica Scienti
Characterization of wine neutral oligosaccharides by Hydrophilic Interaction Liquid Chromatography coupled to ESI-MS
No full textCharacterization of wine neutral oligosaccharides by Hydrophilic Interaction Liquid Chromatography coupled to ESI-MS. In vino analytica Scienti
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