Selective linkage detection of O-sialoglycan isomers by negative electrospray ionization ion trap tandem mass spectrometry

9 páginas, 6 figuras, 2 esquemas.-- El pdf del artículo es la versión de autor.Sialylated O-linked oligosaccharides are involved in many biological processes, such as cell-cell interactions, cell-substance adhesion, and virus-host interactions. These activities depend on their structure, which is frequently determined by tandem mass spectrometry. However, these spectra are frequently analyzer-dependent, which makes it difficult to develop widely applicable analytical methods. In order to deepen the origin of this behavior, two couples of isomers of sialylated O-linked oligosaccharides, NeuAcα2-3Galβ1-3GalNAc-ol/Galβ1-3(NeuAcα2-6)GalNAc-ol and NeuGcα2-3Galβ1-3GalNAc-ol/Galβ1-3(NeuGcα2-6)GalNAc-ol, were analyzed by liquid chromatography/negative electrospray ionization ion trap tandem mass spectrometry (LC/ESI(−)-MSn) using both an ion trap and a triple quadrupole mass spectrometer. Results clearly showed that while ions obtained in the triple quadrupole instrument fitted very well with the standard fragmentation routes, in the ion trap several intense ions could not be explained by these rules, specially a fragment at m/z 597. Furthermore, this ion was observed in the mass spectrum of those isomers that sialic acid binds to GalNAc by an α2-6 linkage. From the MS3 spectrum of this ion an unexpected structure was deduced, and it led to propose alternative fragmentation pathways. Molecular mechanics calculations suggested that the found atypical route could be promoted by a hydrogen bond located only in α2-6-linked oligosaccharides. It has also been demonstrated that this process follows a slow kinetic, explaining why it cannot be observed using an ion beam-type mass analyzer. In conclusion, ion traps seem to be more appropriate than triple quadrupoles to develop a reliable analytical method to distinguish between isomeric O-linked glycans.Financial support was obtained from projects ANALISYC S-0505/ AGR/000312 from the Comunidad de Madrid, Consolider Ingenio 2010 (FUN-C-FOOD); CSD 2007-00063 from the Ministerio de Educación y Ciencia; and PIF-SIALOBIOTIC 200870F010-1 and -2 from CSIC.Peer reviewe

Proanthocyanidin characterization and bioactivity of extracts from different parts of Uncaria tomentosa L. (cat’s claw)

This article belongs to the Special Issue Dietary Antioxidants and Health Promotion.-- et al.Apart from alkaloids, bioactive properties of Uncaria tomentosa L. have been attributed to its phenolic constituents. Although there are some reports concerning low-molecular-weight polyphenols in U. tomentosa, its polymeric phenolic composition has been scarcely studied. In this study, phenolic-rich extracts from leaves, stems, bark and wood (n = 14) of Uncaria tomentosa plants from several regions of Costa Rica were obtained and analysed in respect to their proanthocyanidin profile determined by a quadrupole-time-of-flight analyser (ESI-QTOF MS). Main structural characteristics found for U. tomentosa proanthocyanidins were: (a) monomer composition, including pure procyanidins (only composed of (epi)catechin units) and propelargonidins (only composed of (epi)afzelechin units) as well as mixed proanthocyanidins; and (b) degree of polymerization, from 3 up to 11 units. In addition, U. tomentosa phenolic extracts were found to exhibit reasonable antioxidant capacity (ORAC (Oxygen Radical Absorbance Capacity) values between 1.5 and 18.8 mmol TE/g) and antimicrobial activity against potential respiratory pathogens (minimum IC of 133 µg/mL). There were also found to be particularly cytotoxic to gastric adenocarcinoma AGS and colon adenocarcinoma SW620 cell lines. The results state the particularities of U. tomentosa proanthocyanidins and suggest the potential value of these extracts with prospective use as functional ingredients.This project was partially funded by grant from the Spanish International Development Cooperation Agency (AECID) (Ref. A/023397/09 and A/030037/10) and a joint grant from the Costa Rica-USA Foundation (CRUSA) and the Spanish Scientific Research Council (CSIC) (Ref. CR0024). Authors also thank financial support from the Comunidad de Madrid (Spain) and European funding from FEDER program (projects AVANSECAL-CM S2013/ABI-3028 and ALIBIRD-CM S2013/ABI-2728) and from the University of Costa Rica. Special thanks are due to Eng. Juan Jose Cordero from Costa Rican National Production Council (CNP).Peer Reviewe

Prebiotic potential of a new sweetener based on galactooligosaccharides and modified mogrosides

This study was conducted to investigate the sweetness intensity and the potential fecal microbiome modulation of galactooligosaccharides in combination with enzymatically modified mogrosides (mMV-GOS), both generated through a patented single-pot synthesis. Sweetness intensity was performed in vivo by trained sensory panelists. The impact on the human fecal microbiome was evaluated by in vitro pH-controlled batch fermentation, and bacterial populations and organic acid concentrations were measured by qPCR and GC-FID, respectively. Significant growth (p ≤ 0.05) during the fermentation at 10 h of bacterial populations includes Bifidobacterium (8.49 ± 0.44 CFU/mL), Bacteroides (9.73 ± 0.32 CFU/mL), Enterococcus (8.17 ± 0.42 CFU/mL), and Clostridium coccoides (6.15 ± 0.11 CFU/mL) as compared to the negative control counts for each bacterial group (7.94 ± 0.27, 7.84 ± 1.11, 7.52 ± 0.37, and 5.81 ± 0.08 CFU/mL, respectively) at the same time of fermentation. Likewise, the corresponding significant increase in production of SCFA in mMV-GOS at 10 h of fermentation, mainly seen in acetate (20.32 ± 2.56 mM) and propionate (9.49 ± 1.44 mM) production compared to a negative control at the same time (8.15 ± 1.97 and 1.86 ± 0.24 mM), is in line with a positive control (short-chain fructooligosaccharides; 46.74 ± 12.13 and 6.51 ± 1.91 mM, respectively) revealing a selective fermentation. In conclusion, these substrates could be considered as novel candidate prebiotic sweeteners, foreseeing a feasible and innovative approach targeting the sucrose content reduction in food. This new ingredient could provide health benefits when evaluated in human studies by combining sweetness and prebiotic fiber functionality

A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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Hydrophilic interaction liquid chromatography coupled to mass spectrometry for the characterization of prebiotic galactooligosaccharides

El pdf del artículo es la versión pre-print.Three different stationary phases (sulfoalkylbetaine zwitterionic, polyhydroxyethyl aspartamide and ethylene bridge hybrid (BEH) with trifunctionally bonded amide), operating at hydrophilic interaction liquid chromatographic (HILIC) mode, have been assayed and compared for the analysis of complex mixtures of galactooligosaccharides (GOS). Chromatographic methods have been optimized to obtain the best separation between two consecutive galactose containing standards and maltodextrins, measured on the basis of resolution. Influence of several factors such as chemical modifiers (formic acid, ammonium acetate and ammonium hydroxide), organic solvent and gradients of the mobile phases in the separation of oligosaccharides have been studied. The best results were achieved on the BEH amide stationary phase, using acetonitrile:water with 0.1% ammonium hydroxide as mobile phase, where the most of oligosaccharides were successfully resolved. Characteristic MS 2 fragmentation profiles of disaccharides containing galactose, glucose and/or fructose units with different linkages were evaluated and used for the characterization of di-, tri- and tetrasaccharides of three commercial prebiotic GOS mixtures (GOS-1, GOS-2 and GOS-3) by HILIC-MS n. Similar qualitative and quantitative composition was observed for GOS-1 and GOS-3, whereas different linkages and abundances were detected for GOS-2. In general, (1→4) and (1→6) glycosidic linkages were the main structures found in GOS, although (1→2) and (1→3) linkages were also identified. Regarding molecular weight, up to pentasaccharides were detected in these samples, disaccharides being the most abundant carbohydrates. © 2011 Elsevier B.V.This work has been financed by projects PIF-SIALOBIOTIC 200870F010-1, -2 (CSIC), from Junta de Comunidades de Castilla- La Mancha and European regional development fund (ERDF) (POII10-0178-4685) and AGL2009-11909 (Ministerio de Ciencia e Innovación). O. Hernández-Hernández thanks CSIC for a JAE Predoc grant.Peer Reviewe

Volatile mass spectral fingerprinting by SPME MS for classification of honey botanical source

This work has been funded by the Ministerio de Economía, Industria y Competitividad of Spain (project AGL2016-80475-R, AEI/FEDER, UE) and by the Comunidad de Madrid and European funding from FSE and FEDER programs (project S2018/BAA-4393, AVANSECAL-II-CM)

Comprehensive evaluation of direct injection mass spectrometry for the quantitative profiling of volatiles in food samples

Although qualitative strategies based on direct injection mass spectrometry (DiMS) have recently emerged as an alternative for the rapid classification of food samples, the potential of these approaches in quantitative tasks has scarcely been addressed to date. In this paper, the applicability of different multivariate regression procedures to data collected by DiMS from simulated mixtures has been evaluated. The most relevant factors affecting quantitation, such as random noise, the number of calibration samples, type of validation, mixture complexity and similarity of mass spectra, were also considered and comprehensively discussed. Based on the conclusions drawn from simulated data, and as an example of application, experimental mass spectral fingerprints collected by direct thermal desorption coupled to mass spectrometry were used for the quantitation of major volatiles in Thymus zygis subsp. zygis chemotypes. The results obtained, validated with the direct thermal desorption coupled to gas chromatography-mass spectrometry method here used as a reference, show the potential of DiMS approaches for the fast and precise quantitative profiling of volatiles in foods.Peer Reviewe

Volatile fingerprinting by solid-phase microextraction mass spectrometry for rapid classification of honey botanical source

Volatile fingerprinting by Headspace-Solid-Phase Microextraction followed by Direct Injection Mass Spectrometry (HS-SPME DIMS) has been assessed for the first time as an alternative approach to gas chromatographic methods (HS-SPME GC-MS) for the rapid classification of honey botanical origin. In order to fully evaluate the potential of SPME for honey authentication, samples from different botanical sources (eucalyptus, citrus, acacia, rosemary and honeydew) were analyzed by both approaches using either carboxen/polydimethylsiloxane (C/PDMS) or polyacrylate SPME fibers. These datasets were further subjected to different supervised and unsupervised chemometric techniques, including powerful machine learning methods such as FreeViz, not previously applied for this purpose. The best overall classification rate (99% success), outperforming that provided by GC-MS data (98.25% success), was obtained when partial least squares-linear discriminant analysis was applied to mass spectral fingerprints gathered by C/PDMS fiber. The HS-SPME DIMS approach here optimized is shown as an advantageous alternative in terms of analysis time over chromatographic methods (2 vs 50 min), as well as a reliable and cost-efficient approach for honey source authentication issues both in research and food industry fields.This work is part of the I+D+I projects AGL2016-80475-R funded by the Spanish MINECO/AEI/FEDER, UE and PID2019-106405GB-I00 financed by MCIN/AEI/10.13039/501100011033. Authors also thank the Comunidad of Madrid and European funding from FSE and FEDER programs for financial support (project S2018/BAA-4393, AVANSECAL-II-CM)

PROFILING FOOD VOLATILES BY DIRECT COUPLING OF THERMAL DESORPTION AND MASS SPECTROMETRY. DIFFERENTIATION OF THYME CHEMOTYPES

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Congener-specific determination of hydroxylated polychlorinated biphenyls by polar-embedded reversed-phase liquid chromatography-tandem mass spectrometry

This paper reports the development of an LC-ESI-MS method for the sensitive determination of hydroxylated polychlorinated biphenyls (OH-PCBs) in human serum samples. Congener-specific separation was achieved by using a polar-embedded stationary phase, previously optimized for the working group, which provided better separation of isobaric compounds than the common octadecylsilane phases. MS fragmentation patterns and energies showed differences among OH-PCB congeners, mainly depending on the position of OH-group and the number of chlorine atoms in the molecule, although the most intense transitions were always those corresponding to the neutral loss of an HCl group from the quasi-molecular ion cluster. The method allowed the determination of OH-PCBs with good linearity (dynamic linear range of four orders of magnitude with R higher than 0.995) and precision (relative standard deviations of absolute areas lower than 10%), and with better sensitivity than other similar methods previously described in the literature. Matrix effect has been evaluated and reduced to less than 10% by the addition of isotopically labeled standards and a 10-fold dilution of the final sample extract. The low iLODs provided by the developed method (from 1.2 to 5.4 fg µL for all the OH-PCBs studied, except 4′-OH[sbnd]CB108, whose iLOD was 61 fg µL) allows dilution without losses of detected peaks. Finally, the applicability of the method has been demonstrated by analyzing human serum samples belonging to an interlaboratory exercise.Authors thank Comunidad of Madrid and European funding from FSE and FEDER program (S2018/BAA-4393–AVANSECAL-II- CM) and the Spanish Ministry of Economy and Competitiveness (projects AGL2012–37201 and AGL2016–80475-R) for the financial support. We are particularly grateful to Laura Herrero and Sagrario Calvarro for their technical ai