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

Diagnóstico del conocimiento taxonómico y florístico de las plantas vasculares del norte de México

Resumen Antecedentes: El conocimiento taxonómico y florístico de las plantas vasculares del norte de México presenta avances relevantes, aunque disgregados. Por lo anterior, es crítico hacer un diagnóstico para definir estrategias que los unifiquen y complementen. Preguntas: ¿cuál es la riqueza y endemismo de las plantas vasculares en el norte de México?, ¿en cuáles de sus áreas deben concentrarse los esfuerzos de exploración? Sitio de estudio: norte de México (Chihuahua, Coahuila, Durango y Nuevo León). Métodos: Se desarrolló una base de datos de plantas vasculares del norte de México a partir de la del Herbario CIIDIR, complementada con registros provenientes de la Universidad de Chihuahua, Universidad Antonio Narro y Universidad de Nuevo León, así como de revisión de trabajos taxonómicos y de los herbarios ANSM, CFNL, CIIDIR y FZ-UACH. Se calculó la riqueza y endemismo por estado y por ecorregión; se definieron los grupos y áreas geográficas mejor conocidos y los huecos en conocimiento; y se elaboró una relación de los herbarios, programas en botánica y botánicos en la región. Resultados: Se registran 8,503 especies, 1,599 géneros y 210 familias de plantas vasculares; 15 géneros son endémicos estrictos de la región. La mayor riqueza se registra para Durango (4,954 especies, 58 % del total). La Sierra Madre Occidental (en su porción para la zona estudiada) es la ecorregión con más especies (3,565), seguida por la Sierra Madre Oriental (2,862) y el Desierto Chihuahuense (2,602). Chihuahua y la Sierra Madre Occidental son el estado y la ecorregión menos explorados, mientras que la ecorregión mejor explorada es el Desierto Chihuahuense. Conclusiones: Las cifras de riqueza y endemismo presentadas reflejan el estado del conocimiento actual, sin embargo, se requiere incrementar los inventarios florísticos, las revisiones taxonómicas y los estudios ecológicos para contar con información más precisa y exacta del panorama real. Palabras clave: Chihuahua, Coahuila, Durango, flora, Nuevo León. A diagnosis of the taxonomic and floristic knowledge on vascular plants from northern Mexico Abstract Background: The taxonomic and floristic knowledge of vascular plants in northern Mexico presents relevant, though disaggregated advances. Therefore, it is crucial to make a diagnostic in order to define strategies to unify and complement the knowledge generated. Questions: how many species of vascular plants are there in northern Mexico? How many of these are restricted to this region? Which are the areas where main exploration efforts should be concentrated? Study site: northern Mexico (states of Chihuahua, Coahuila, Durango and Nuevo Léon). Methods: A database of vascular plants from northern Mexico was developed from the database of the CIIDIR Herbarium adding records gattered at the Universities of Chihuahua, Antonio Narro, and Nuevo Leon, as well as with data from taxonomic reviews and from herbaria (ANSM, CFNL, CIIDIR, FZ-UACH). From the report generated, richness and endemism per state and ecoregion were calculated. The best known groups and geographic areas were identified, as well as knowledge gaps; a list of the herbaria, programmes in botany and botanists in the region was compiled. Results: 8,503 species, 1,599 genera and 210 families of vascular plants were retrieved by the revision. 15 genera are strict endemics to the region. Durango is the richest state (4,954 species, 58 % of the total). Sierra Madre Occidental is the ecoregion with the higher richness (3,565 species, considering only its portion in the studied states), followed by Sierra Madre Oriental (2,862) and Chihuahuan Desert (2,602). The better known state and ecoregion are Chihuahua and Sierra Madre Occidental. Chihuahuan Desert is the region better explored. Conclusions: the magnitude of the richness and endemism presented here reflects the current knowledge, nonetheless, it is necessary to increase floristic inventaries, taxonomic revision and ecological studies to acquire more precise and exact information of the real scene. Key words: Chihuahua, Coahuila, Durango, flora, Nuevo Leó

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)

Fast and simultaneous determination of endocrine disrupting compounds by ultra-high performance liquid chromatography-tandem mass spectrometry

A rapid and sensitive analytical method for the simultaneous determination of thirteen endocrine disruptors (five phthalates, seven parabens, and bisphenol A) in a single chromatographic run has been developed for the first time. The separation method, based on ultra-high performance liquid chromatography (UHPLC), allows the separation of all compounds (including isobaric pairs) in less than 4.1 min. The fast polarity switching mode of the triple quadrupole mass spectrometer used enables the registration of positive (phthalates) and negative (parabens and BPA) ions in the same acquisition run. A Response Surface Methodology was used for the optimization of the method. The optimum elution program starts with 0.2 min in isocratic conditions (79.8% water; 20% acetonitrile, 0.2% ammonium formate 5 mM at pH 10.2), then the content of acetonitrile is linearly increased in 2 min up to 42%, and later up to 98% in 1.1 min. The analytical characteristics of the developed method were satisfactory. The method is robust and showed a linear response with determination coefficients (R2) higher than 0.991 in the range 5.0-2000 pg on column (or higher) for all the compounds investigated. Instrumental intra- and inter-day precision (expressed as relative standard deviation) were lower than 12% for parabens and bisphenol A, and between 5.9% and 27% for phthalates. Instrumental detection and quantification limits (iLODs and iLOQs) were in the range of medium-high femtograms (270-1300 pg on column for iLODs). Finally, the suitability of the developed method was demonstrated through its application to the analysis of commercial personal care products (shower gels) without any sample treatment, only a simple dilution, being possible to determine the simultaneous presence of phthalates, parabens, and bisphenol A in almost all the gels analyzed.AGL2012-37201 S2013/ABI-3028/AVANSECALPeer 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)

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

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

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Plasticisers and preservatives in commercial milk products: A comprehensive study on packages used in the Spanish market

A comprehensive study on packaging used in commercially available milk products from Spanish markets has been presented. Concentrations of four phthalates, seven parabens and BPA were determined in forty-two milk products. Eleven brands and five types of packaging (metallic aluminium bag, carton, high-density polyethylene, metal pail and polyethylene terephthalate) were included in the study. BPA showed the lowest concentrations (8.3 pg/g f.w.), far below those of phthalates (6431 pg/g f.w.) and parabens (6234 pg/g f.w.). Metallic aluminium bags were the least migrating packaging (considering plasticisers and monomers) followed by HDPE bottles, in the case of phthalates. Parabens showed their highest concentrations for fresh-milk samples. Levels found were far below the specific migration limits established by the EU and the cumulative hazard index was lower than 1, indicating that adverse health effects were not expected. In general, the results found in Spanish samples were lower than those reported in other countries.Authors thank Mrs. Sagrario Calvarro for UHPLC-QqQ maintenance and control. This work was supported by the Spanish Ministry of Economy and Competitiveness [AGL2012-37201] and Comunidad of Madrid (Spain) and European funding from FSE and FEDER program [S2018/BAA-4393 – AVANSECAL-II-CM]