Electron-activated dissociation (EAD) for the complementary annotation of metabolites and lipids through data-dependent acquisition analysis and feature-based molecular networking, applied to the sentinel amphipod Gammarus fossarum.

The past decades have marked the rise of metabolomics and lipidomics as the -omics sciences which reflect the most phenotypes in living systems. Mass spectrometry-based approaches are acknowledged for both quantification and identification of molecular signatures, the latter relying primarily on fragmentation spectra interpretation. However, the high structural diversity of biological small molecules poses a considerable challenge in compound annotation. Feature-based molecular networking (FBMN) combined with database searches currently sets the gold standard for annotation of large datasets. Nevertheless, FBMN is usually based on collision-induced dissociation (CID) data, which may lead to unsatisfying information. The use of alternative fragmentation methods, such as electron-activated dissociation (EAD), is undergoing a re-evaluation for the annotation of small molecules, as it gives access to additional fragmentation routes. In this study, we apply the performances of data-dependent acquisition mass spectrometry (DDA-MS) under CID and EAD fragmentation along with FBMN construction, to perform extensive compound annotation in the crude extracts of the freshwater sentinel organism Gammarus fossarum. We discuss the analytical aspects of the use of the two fragmentation modes, perform a general comparison of the information delivered, and compare the CID and EAD fragmentation pathways for specific classes of compounds, including previously unstudied species. In addition, we discuss the potential use of FBMN constructed with EAD fragmentation spectra to improve lipid annotation, compared to the classic CID-based networks. Our approach has enabled higher confidence annotations and finer structure characterization of 823 features, including both metabolites and lipids detected in G. fossarum extracts.

Advances in Ultra-High-Resolution Mass Spectrometry for Pharmaceutical Analysis.

Pharmaceutical analysis refers to an area of analytical chemistry that deals with active compounds either by themselves (drug substance) or when formulated with excipients (drug product). In a less simplistic way, it can be defined as a complex science involving various disciplines, e.g., drug development, pharmacokinetics, drug metabolism, tissue distribution studies, and environmental contamination analyses. As such, the pharmaceutical analysis covers drug development to its impact on health and the environment. Moreover, due to the need for safe and effective medications, the pharmaceutical industry is one of the most heavily regulated sectors of the global economy. For this reason, powerful analytical instrumentation and efficient methods are required. In the last decades, mass spectrometry has been increasingly used in pharmaceutical analysis both for research aims and routine quality controls. Among different instrumental setups, ultra-high-resolution mass spectrometry with Fourier transform instruments, i.e., Fourier transform ion cyclotron resonance (FTICR) and Orbitrap, gives access to valuable molecular information for pharmaceutical analysis. In fact, thanks to their high resolving power, mass accuracy, and dynamic range, reliable molecular formula assignments or trace analysis in complex mixtures can be obtained. This review summarizes the principles of the two main types of Fourier transform mass spectrometers, and it highlights applications, developments, and future perspectives in pharmaceutical analysis.

Molecular networking and collision cross section prediction for structural isomer and unknown compound identification in plant metabolomics: a case study applied to Zhanthoxylum heitzii extracts.

Mass spectrometry-based plant metabolomics allow large-scale analysis of a wide range of compounds and the discovery of potential new active metabolites with minimal sample preparation. Despite recent tools for molecular networking, many metabolites remain unknown. Our objective is to show the complementarity of collision cross section (CCS) measurements and calculations for metabolite annotation in a real case study. Thus, a systematic and high-throughput investigation of root, bark, branch, and leaf of the Gabonese plant Zhanthoxylum heitzii was performed through ultra-high performance liquid chromatography high-resolution tandem mass spectrometry (UHPLC-QTOF/MS). A feature-based molecular network (FBMN) was employed to study the distribution of metabolites in the organs of the plants and discover potential new components. In total, 143 metabolites belonging to the family of alkaloids, lignans, polyphenols, fatty acids, and amino acids were detected and a semi-quantitative analysis in the different organs was performed. A large proportion of medical plant phytochemicals is often characterized by isomerism and, in the absence of reference compounds, an additional dimension of gas phase separation can result in improvements to both quantitation and compound annotation. The inclusion of ion mobility in the ultra-high performance liquid chromatography mass spectrometry workflow (UHPLC-IMS-MS) has been used to collect experimental CCS values in nitrogen and helium (CCSN2 and CCSHe) of Zhanthoxylum heitzii features. Due to a lack of reference data, the investigation of predicted collision cross section has enabled comparison with the experimental values, helping in dereplication and isomer identification. Moreover, in combination with mass spectra interpretation, the comparison of experimental and theoretical CCS values allowed annotation of unknown features. The study represents a practical example of the potential of modern mass spectrometry strategies in the identification of medicinal plant phytochemical components.

Micelles of the chiral biocompatible surfactant (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB): molecular dynamics and fragmentation patterns in the gas phase.

RATIONALE: The study of self-assembly processes of surfactant molecules in the gas phase is of great interest for several theoretical and technological reasons related to their possible exploitation as drug carriers, protein shields and cleaning agents in the gas phase. METHODS: The stability and fragmentation patterns of singly and multiply charged (either positively or negatively) aggregates of the surfactant (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethyl ammonium bromide (DMEB) in the gas phase have been studied by ion mobility mass spectrometry and tandem mass spectrometry. Molecular dynamics (MD) simulations of positively and negatively singly and multiply charged DMEB aggregates have been performed to obtain structural and energetics information. Finally, in order to ascertain some clues on the DMEB growth mechanism, quantum mechanics calculations were carried out. RESULTS: It has been evidenced that positively and negatively singly charged aggregates at low collision energy decompose preferentially by loss of only one DMEB molecule. Increasing the collision energy, the loss of neutrals becomes increasingly abundant. Multiply charged DMEB aggregates are unstable and decompose forming singly charged monomers or dimers. MD simulations show reverse micelle-like structures with polar heads somewhat segregated into the aggregate interior. Finally, a good correlation between experimental and calculated collisional cross sections (CCS) was found. CONCLUSIONS: The fragmentation pathways of DMEB charged species evidenced for singly charged aggregates exhibit features similar to that of other detergent aggregates, but multiply charged aggregates showed a system-specific behavior. QM calculations on the optimized structures (21+ , 31+ , 11- and 21- ) indicate that the most determinant interactions are due to an OH---Br hydrogen bonding that is also involved in the link between monomeric DMEB units. The MD models gave CCS values in good agreement with experimental ones, evidenced by a less strict reverse micelle-like structure and a reasonably spread bromine anion distribution Copyright © 2017 John Wiley & Sons, Ltd.

Synthetic and natural small molecule TLR4 antagonists inhibit motoneuron death in cultures from ALS mouse model.

Increasing evidence indicates that inflammatory responses could play a critical role in the pathogenesis of motor neuron injury in amyotrophic lateral sclerosis (ALS). Recent findings have underlined the role of Toll-like receptors (TLRs) and the involvement of both the innate and adaptive immune responses in ALS pathogenesis. In particular, abnormal TLR4 signaling in pro-inflammatory microglia cells has been related to motoneuron degeneration leading to ALS. In this study the effect of small molecule TLR4 antagonists on in vitro ALS models has been investigated. Two different types of synthetic glycolipids and the phenol fraction extracted from commercial extra-virgin olive oil (EVOO) were selected since they efficiently inhibit TLR4 stimulus in HEK cells by interacting with the TLR4·MD-2 complex and CD14 co-receptor. Here, TLR4 antagonists efficiently protected motoneurons from LPS-induced lethality in spinal cord cultures, and inhibited the interleukine-1ß production by LPS-stimulated microglia. In motoneurons/glia cocultures obtained from wild type or SOD1 G93A mice, motoneuron death induced by SOD1mut glia was counteracted by TLR4 antagonists. The release of nitric oxide by LPS treatment or SOD1mut glia was also inhibited by EVOO, suggesting that the action of this natural extract could be mainly related to the modulation of this inflammatory mediator.

Electrospray ion mobility mass spectrometry of positively and negatively charged (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide aggregates.

RATIONALE: Self-assembling processes of surfactants in the gas phase constitute a developing research field of interest since they allow information to be gained on the peculiar structural organization of these aggregates, on their ability to incorporate from small molecules up to proteins and on their possible use as carriers of drugs in the gas phase or as cleaning agents and exotic reaction media. METHODS: The mass spectra of charged aggregates of the chiral surfactant (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) in the gas phase have been recorded using a Synapt G2-Si mass spectrometer in the positive and negative ion mode. For comparison purposes, the mass spectra of sodium bis(2-ethylhexyl)sulfosuccinate and sodium octane sulfonate aggregates have also been recorded under the same experimental conditions. The collisional cross sections of positively and negatively charged DMEB aggregates were obtained through an appropriate calibration of the measured drift times. RESULTS: For all the surfactants investigated, it has been found that there is a lowest and a highest limit of the aggregation number at each charge state: no aggregates are found outside this range. Moreover, the occurrence at each aggregation number and extra charge of a unique value of drift time points toward aggregates whose conformations do not show discernible shape change in the experiment time scale. The analysis of the collisional cross sections emphasizes that the DMEB aggregates are nearly spherical clusters somewhat affected by the charge state and constituted by interlaced polar and apolar domains. CONCLUSIONS: The analysis of all the experimental findings indicates that in the gas phase DMEB forms supramolecular aggregates characterized by an internal organization whose stability is triggered by the charge state. The comparison of the behavior of DMEB aggregates with that of sodium bis(2-ethylhexyl)sulfosuccinate and sodium octane sulfonate aggregates allows us to highlight the effects on the aggregate organization in gas phase due to nature of the head group and alkyl chain steric hindrance.

Functional characterization of E. coli LptC: interaction with LPS and a synthetic ligand.

Lipopolysaccharide (LPS), the main cell-surface molecular constituent of Gram-negative bacteria, is synthesized in the inner membrane (IM) and transported to the outer membrane (OM) by the Lpt (lipopolysaccharide transport) machinery. Neosynthesized LPS is first flipped by MsbA across the IM, then transported to the OM by seven Lpt proteins located in the IM (LptBCFG), in the periplasm (LptA), and in the OM (LptDE). A functional OM is essential to bacterial viability and requires correct placement of LPS in the outer leaflet. Therefore, LPS biogenesis represents an ideal target for the development of novel antibiotics against Gram-negative bacteria. Although the structures of Lpt proteins have been elucidated, little is known about the mechanism of LPS transport, and few data are available on Lpt­LPS binding. We report here the first determination of the thermodynamic and kinetic parameters of the interaction between LptC and a fluorescent lipo-oligosaccharide (fLOS) in vitro. The apparent dissociation constant (Kd) of the fLOS­LptC interaction was evaluated by two independent methods. The first was based on fLOS capture by resin-immobilized LptC; the second used quenching of LptC intrinsic fluorescence by fLOS in solution. The Kd values by the two methods (71.4 and 28.8 µm, respectively) are very similar, and are of the same order of magnitude as that of the affinity of LOS for the upstream transporter, MsbA. Interestingly, both methods showed that fLOS binding to LptC is mostly irreversible, thus reflecting the fact that LPS can be released from LptC only when energy is supplied by ATP or in the presence of a higher-affinity LptA protein. A fluorescent glycolipid was synthesized: this also interacted irreversibly with LptC, but with lower affinity (apparent Kd=221 µM). This compound binds LptC at the LPS binding site and is a prototype for the development of new antibiotics targeting LPS transport in Gram-negative bacteria.

Modulation of CD14 and TLR4·MD-2 activities by a synthetic lipid A mimetic.

Monosaccharide lipid A mimetics based on a glucosamine core linked to two fatty acid chains and bearing one or two phosphate groups have been synthesized. Compounds 1 and 2, each with one phosphate group, were practically inactive in inhibiting LPS-induced TLR4 signaling and cytokine production in HEK-blue cells and murine macrophages, but compound 3, with two phosphate groups, was found to be active in efficiently inhibiting TLR4 signal in both cell types. The direct interaction between compound 3 and the MD-2 coreceptor was investigated by NMR spectroscopy and molecular modeling/docking analysis. This compound also interacts directly with the CD14 receptor, stimulating its internalization by endocytosis. Experiments on macrophages show that the effect on CD14 reinforces the activity on MD-2·TLR4 because compound 3's activity is higher when CD14 is important for TLR4 signaling (i.e., at low LPS concentration). The dual targeting of MD-2 and CD14, accompanied by good solubility in water and lack of toxicity, suggests the use of monosaccharide 3 as a lead compound for the development of drugs directed against TLR4-related syndromes.

ToF-SIMS imaging shows specific lipophilic vitamin alterations in chronic reprotoxicity caused by the emerging contaminant Pravastatin in Gammarus fossarum.

Blood lipid-lowering agents, such as Pravastatin, are among the most frequently used pharmaceuticals released into the aquatic environment. Although their effects on humans are very well understood, their consequences on freshwater organisms are not well known, especially in chronic exposure conditions. Gammarus fossarum is commonly used as sentinel species in ecotoxicology because of its sensitivity to a wide range of environmental contaminants and the availability of standardized bioassays. Moreover, there is an increased interest in linking molecular changes in sentinel species, such as gammarids, to observed toxic effects. Here, we performed a reproductive toxicity assay on females exposed to different concentrations of pravastatin (30; 300; 3,000 and 30,000 ng L-1) during two successive reproductive cycles and we applied ToF-SIMS imaging to evaluate the effect of pravastatin on lipid homeostasis in gammarids. Reproductive bioassay showed that pravastatin could affect oocyte development in Gammarus fossarum inducing embryotoxicity in the second reproductive cycle. Mass spectrometry imaging highlighted the disruption in vitamin E production in the oocytes of exposed female gammarids at the second reproductive cycle, while limited alterations were observed in other lipid classes, regarding both production and tissue distribution. The results demonstrated the interest of applying spatially resolved lipidomics by mass spectrometry imaging to assess the molecular effects induced by long-term exposure to environmental pharmaceutical residues in sentinel species.

Concomitant investigation of crustacean amphipods lipidome and metabolome during the molting cycle by Zeno SWATH data-independent acquisition coupled with electron activated dissociation and machine learning.

BACKGROUND: DIA (Data-Independent Acquisition) is a powerful technique in Liquid Chromatography coupled with high-resolution tandem Mass Spectrometry (LC-MS/MS) initially developed for proteomics studies and recently emerging in metabolomics and lipidomics. It provides a comprehensive and unbiased coverage of molecules with improved reproducibility and quantitative accuracy compared to Data-Dependent Acquisition (DDA). Combined with the Zeno trap and Electron-Activated Dissociation (EAD), DIA enhances data quality and structural elucidation compared to conventional fragmentation under CID. These tools were applied to study the lipidome and metabolome of the freshwater amphipod Gammarus fossarum, successfully discriminating stages and highlighting significant biological features. Despite being underused, DIA, along with the Zeno trap and EAD, holds great potential for advancing research in the omics field. RESULTS: DIA combined with the Zeno trap enhances detection reproducibility compared to conventional DDA, improving fragmentation spectra quality and putative identifications. LC coupled with Zeno-SWATH-DIA methods were used to characterize molecular changes in reproductive cycle of female gammarids. Multivariate data analysis including Principal Component Analysis and Partial Least Square Discriminant Analysis successfully identified significant features. EAD fragmentation helped to identify unknown features and to confirm their molecular structure using fragmentation spectra database annotation or machine learning. EAD database matching accurately annotated five glycerophospholipids, including the position of double bonds on fatty acid chain moieties. SIRIUS database predicted structures of unknown features based on experimental fragmentation spectra to compensate for database incompleteness. SIGNIFICANCE: Reproducible detection of features and confident identification of putative compounds are pivotal stages within analytical pipelines. The DIA approach combined with Zeno pulsing enhances detection sensitivity and targeted fragmentation with EAD in positive polarity provides orthogonal fragmentation information. In our study, Zeno-DIA and EAD thereby facilitated a comprehensive and insightful exploration of pertinent biological molecules associated with the reproductive cycle of gammarids. The developed methodology holds great promises for identifying informative biomarkers on the health status of an environmental sentinel species.

Tuning the nature of the fluorescent state: a substituted polycondensed dye as a case study.

An extensive spectroscopic analysis is presented of an elongated polycondensed dye with a donor-acceptor substitution. The charge-transfer (CT) state, polarized along the long molecular axis, is close in energy to a local excitation (LE) of the polycondensed system, roughly polarized along the short molecular axis, which makes this system particularly suitable to investigate the subtle LE/CT interplay. An essential-state model is presented that quantitatively reproduces absorption and fluorescence spectra, as well as fluorescence emission and excitation anisotropy spectra collected in solvents of different polarity and viscosity, which sets a sound basis for the understanding of how solvent polarity and solvent relaxation affect the nature of low-lying excitations. The markedly different fluorescence emission and excitation anisotropy spectra measured in glassy and liquid polar solvents unambiguously demonstrate the major role played by solvent relaxation in the definition of fluorescence properties of the dye.

Direct introduction MALDI FTICR MS based on dried droplet deposition applied to non-targeted metabolomics on Pisum Sativum root exudates.

Non-targeted metabolomic approaches based on direct introduction (DI) through a soft ionization source are nowadays used for large-scale analysis and wide cover-up of metabolites in complex matrices. When coupled with ultra-high-resolution Fourier-Transform ion cyclotron resonance (FTICR MS), DI is generally performed through electrospray (ESI), which, despite the great analytical throughput, can suffer of matrix effects due to residual salts or charge competitors. In alternative, matrix assisted laser desorption ionization (MALDI) coupled with FTICR MS offers relatively high salt tolerance but it is mainly used for imaging of small molecule within biological tissues. In this study, we report a systematic evaluation on the performance of direct introduction ESI and MALDI coupled with FTICR MS applied to the analysis of root exudates (RE), a complex mixture of metabolites released from plant root tips and containing a relatively high salt concentration. Classic dried droplet deposition followed by screening of best matrices and ratio allowed the selection of high ranked conditions for non-targeted metabolomics on RE. Optimization of MALDI parameters led to improved reproducibility and precision. A RE desalted sample was used for comparison on ionization efficiency of the two sources and ion enhancement at high salinity was highlighted in MALDI by spiking desalted solution with inorganic salts. Application of a true lyophilized RE sample exhibited the complementarity of the two sources and the ability of MALDI in the detection of undisclosed metabolites suffering of matrix effects in ESI mode.

Exploring the LPS/TLR4 signal pathway with small molecules.

The identification of the bacterial endotoxin receptors for innate immunity, most notably TLR4 (Toll-like receptor 4), has sparked great interest in therapeutic manipulation of the innate immune system. In the present mini-review, several natural and synthetic molecules that modulate the TLR4-mediated LPS (lipopolysaccharide) signalling in animals and humans are considered, and their mechanisms of action are discussed. The process of LPS sensing and signal amplification in humans is based on the sequential action of specific receptors situated in the extracellular side of the innate immunity cells, which bind and transfer LPS to TLR4: LBP (LPS-binding protein), CD14, MD-2 (myeloid differentiation protein 2). We classified the compounds active on TLR4 pathway depending on the specific molecular targets (LPS, LBP, CD14, MD-2 or TLR4). Small molecules developed by our group are described that inhibit LPS-stimulated TLR4 activation by selectively targeting the LPS-CD14 interaction. These compounds have an interesting antiseptic shock, anti-inflammatory and anti-neuropathic pain activity in vivo.

Functionalization of oxide surfaces by terpyridine phosphonate ligands: surface reactions and anchoring geometry.

A strategy for creating a general-purposes surface functionalization platform is reported, based on direct attachment of phosphate groups onto hydroxylated surfaces and subsequent formation of a terpyridine-based monolayer. Such a platform is suitable for the construction, onto technologically relevant oxide surfaces, of single- and multilayer structures of interest in technological applications. In particular, the paper describes the successful attachment of 4-(2,2':6',2''-terpyridine-4-yl)benzenephosphonic acid (1, PPTP) onto a SiO(2) surface previously functionalized by means of Zr-phosphate groups. Two alternative anchoring strategies of the PPTP were explored: (i) a direct one-step way, implying no protection of terpyridinic functionality, and (ii) a three-step way, implying protection and successive deprotection of this group. It was found that, in the first case, the PPTP ligand anchoring to the Zr-containing phosphate layer takes place by means of terpyridinic group. At variance of this, in the second case, due to the protection of the terpyridinic functionality, the anchoring process takes place through the phosphonic group, making the terpyridinic moiety available for further reactions, i.e., multilayer constructs. X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were used to study the functionalized surfaces, providing information on coverage, chemical structure, and stoichiometry of the various functionalized layers and, among the others, clear evidence of the PPTP linkage and orientation.

Recombinant human erythropoietin in the prevention of late anemia in intrauterine transfused neonates with Rh-isoimmunization.

The majority of neonates with Rh-isoimmunization develops late anemia between the second and the sixth week of life. We report the effectiveness of recombinant human erythropoietin (rHuEPO) in preventing late anemia in 25 intrauterine and nonintrauterine-transfused neonates. The neonates were treated from 11+/-4 days after birth to 26+/-14 days (400 U/kg/d of rHuEpo, administered subcutaneously). During rHuEpo therapy, vitamin E, calcium folinate, and iron maltose were administered intramuscularly on a daily basis. Hematocrit, platelet, and neutrophil counts did not differ significantly before and after 21-days therapy. However, average values for reticulocyte showed a significant increase. The hematocrit values in the non-intrauterine transfusion (IUT) group increased progressively from the beginning to the end of the treatment, whereas that in the IUT group remained stable. Reticulocyte count increased during treatment in both groups, but it was significantly elevated in the non-IUT group only. Moreover, we observed that only neonates transfused with IUTs needed transfusions before and after treatment. This study suggests the effectiveness of rHuEpo therapy in the treatment of neonates with Rh-isoimmunization and it highlights how IUTs decrease the neonatal response efficacy. Larger, better if multicentric, randomized controlled trial are needed to definitely state whether rHuEPO safely decreases the incidence of late onset anemia.

Collision Cross Sections of Phosphoric Acid Cluster Anions in Helium Measured by Drift Tube Ion Mobility Mass Spectrometry.

In the last years, ion mobility mass spectrometry (IMS-MS) has improved structural analysis and compound identification by giving access to the collision cross section (CCS). An increasingly wide and accurate database of CCS values is now available but often without assessment of the influence of different instrumental settings on CCS values. Here, we present 75 CCS values in helium (DTCCSHe) for phosphoric acid cluster anions [(H3PO4)n - zH]z- with charge state (z) up to 4-. The CCS values, noted DTCCSHe, were obtained with a commercial drift tube ion mobility mass spectrometer, in helium, by applying a classic multifield approach. Phosphoric acid clusters are fragile structures that allow to evaluate the effect of different experimental conditions on the retention of weak bonds and their effect on CCS values. We probed harsh and soft voltage gradients in the electrospray (ESI) source before the IMS and two different voltage gradients in the post-IMS region. The variations in the ion mobility and mass spectra consisted in a change in the distribution of the cluster anions aggregation numbers (n) and charge states (z), with a higher amount of multiply charged species for the soft pre-IMS voltage gradient and a lower proportion of cluster dissociation for soft post-IMS conditions. However, the CCS values did not change with experimental conditions for a given cluster, as long as it stays intact from the IMS to the mass analyzer. The DTCCSHe were found in good agreement among 3 to 10 replicated values, with a relative standard deviation between 0.1 and 1.7%.

Functional composition and diversity of leaf traits in subalpine versus alpine vegetation in the Apennines.

Mediterranean high mountain grasslands are shaped by climatic stress and understanding their functional adaptations can contribute to better understanding ecosystems' response to global change. The present work analyses the plant functional traits of high-elevation grasslands growing in Mediterranean limestone mountains to explore, at the community level, the presence of different plant strategies for resource use (conservative vs. acquisitive) and functional diversity syndromes (convergent or divergent). Thus, we compared the functional composition and diversity of the above-ground traits related to resource acquisition strategies of subalpine and alpine calcareous grasslands in the central Apennines, a mountain region characterized by a dry-summer Mediterranean climate. We used georeferenced vegetation plots and field-measured plant functional traits (plant maximum height, specific leaf area and leaf dry matter content) for the dominant species of two characteristic vegetation types: the subalpine Sesleria juncifolia community and the alpine Silene acaulis community. Both communities are of particular conservation concern and are rich in endemic species for which plant functional traits are measured here for the first time. We analysed the functional composition and diversity using the community-weighted mean trait index and the functional diversity using Rao's function, and we assessed how much the observed pattern deviated from a random distribution by calculating the respective standardized effect sizes. The results highlighted that an acquisitive resource use strategy and relatively higher functional diversity of leaf traits prevail in the alpine S. acaulis community, optimizing a rapid carbon gain, which would help overcome the constraints exerted by the short growing season. The divergent functional strategy underlines the co-occurrence of different leaf traits in the alpine grasslands, which shows good adaptation to a microhabitat-rich environment. Conversely, in the subalpine S. juncifolia grassland, a conservative resource use strategy and relatively lower functional diversity of the leaf traits are likely related to a high level resistance to aridity over a longer growing season. Our outcomes indicate the preadaptation strategy of the subalpine S. juncifolia grassland to shift upwards to the alpine zone that will become warmer and drier as a result of anthropogenic climate change.

Structure-Activity Relationship in Monosaccharide-Based Toll-Like Receptor 4 (TLR4) Antagonists.

The structure-activity relationship was investigated in a series of synthetic TLR4 antagonists formed by a glucosamine core linked to two phosphate esters and two linear carbon chains. Molecular modeling showed that the compounds with 10, 12, and 14 carbons chains are associated with higher stabilization of the MD-2/TLR4 antagonist conformation than in the case of the C16 variant. Binding experiments with human MD-2 showed that the C12 and C14 variants have higher affinity than C10, while the C16 variant did not interact with the protein. The molecules, with the exception of the C16 variant, inhibited the LPS-stimulated TLR4 signal in human and murine cells, and the antagonist potency mirrored the MD-2 affinity calculated from in vitro binding experiments. Fourier-transform infrared, nuclear magnetic resonance, and small angle X-ray scattering measurements suggested that the aggregation state in aqueous solution depends on fatty acid chain lengths and that this property can influence TLR4 activity in this series of compounds.

Entrapment of amino acids in gas phase surfactant assemblies: The case of tryptophan confined in positively charged (1R,2S)-dodecyl (2-hydroxy-1-methyl-2-phenylethyl) dimethylammonium bromide aggregates.

The ability of positively charged aggregates of the surfactant (1R,2S)-dodecyl(2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium bromide (DMEB) to incorporate D-tryptophan or L-tryptophan in the gas phase has been investigated by electrospray ion mobility mass spectrometry (ESI-IM-MS). Strongly impacted by the pH of the electrosprayed solutions, both protonated (T+ ) and deprotonated (T- ) tryptophan are effectively included into the aggregates, whereas, tryptophan in zwitterionic (T0 ) form is practically absent in singly charged DMEB aggregates but can be found in multiply charged ones. The ability to incorporate tryptophan increases with the aggregation number and charge state of aggregates. More than 1 tryptophan species can be entrapped (aggregates including up to 5 tryptophan are observed). Collision induced dissociation experiments performed on the positively singly charged DMEB hexamer containing 1 T- show that at low collision energies the loss of a DMEB molecule is preferred with respect to the loss of the DMEB cation plus T- species which, in turn, is preferred with respect to the loss of mere tryptophan, suggesting that the deprotonated amino acid is preferentially located in proximity of a DMEB head group and with the ionic moiety pointing towards the core of the aggregate. The analysis of the collision cross sections (CCS) of bare and tryptophan containing aggregates allowed evaluating the contributions of tryptophan and bromide ions to the total aggregate CCS. No significant discrimination between D-tryptophan and L-tryptophan by the chiral DMEB aggregates has been evidenced by mass spectra data, CID experiments, and CCS values.

Triacylglycerols in edible oils: Determination, characterization, quantitation, chemometric approach and evaluation of adulterations.

Vegetable oils are a dietary source of lipids that constitute an essential component of a healthy diet. The commonly used vegetable oils differ significantly for their triacylglycerol (TAG) profile. TAGs represent the principal components of oils and may contain different fatty acids (FA) esterified with glycerol leading to several positional isomers. To differentiate individual TAGs species in edible oils, advanced analysis systems and innovative methods are therefore required. TAGs can be considered as good fingerprints for quality control and many studies have been performed to develop rapid and low cost analytical methods to determinate the authenticity, origin and eventually evidence frauds or adulterations. The present manuscript provides a general overview on the most common vegetable oils TAGs compositions and on the related analytical methodologies recently used. Finally, the chemometric applications developed to assess the authenticity, quality and botanical origin of various edible oils are discussed.