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International audience; The two paintings Infant Bacchanals (Museo Nazionale d’Arte Antica, Palazzo Barberini, Rome, Italy) executed by Nicolas Poussin (Les Andelys, 1594–Rome, 1665) in around 1626 are thought to have been painted “a guazzo”, which means either with a glue or with an egg binding medium. To date, this has never been confirmed through analysis. Dual-beam time-of-flight secondary ion mass spectrometry (TOF-SIMS), using a bismuth cluster liquid metal ion gun and an argon gas cluster ion beam, allows the mapping of organic and inorganic matter on paintings cross sections, with the possibility to acquire submicrometer-resolution mass spectrometry images of the sample, together with high mass resolution using a delayed extraction of secondary ions. The surfaces of cross sections from both paintings were prepared beforehand either by polishing or by microtome cutting and then cleaned with the gas cluster ion beam directly inside the vacuum chamber of the instrument. The nature of the binders in the two paintings was investigated by TOF-SIMS analyses. By considering the uneven physical properties of the heterogeneous analyzed surfaces, several high-resolution images were recorded with different instrument settings. The detection of lipids seems to point toward an oil-containing medium, rather than a glue-binding medium. An emulsion made of oil and glue is another hypothesis to be explored to better understand the artist’s working methods in his early career.

Ion signal detection at the true (unperturbed) cyclotron frequency instead of the conventional reduced cyclotron frequency has remained a formidable challenge since the inception of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Recently, routine FT-ICR MS at the true cyclotron frequency has become a reality with the implementation of ICR cells with narrow aperture detection electrodes (NADEL). Here, we describe the development and implementation of the next generation of these cells, namely, a 2xNADEL ICR cell, which comprises four flat detect and four ∼45° cylindrical excite electrodes, enabling independent ion excitation and quadrupolar ion detection. The performance of the 2xNADEL ICR cell was evaluated on two commercial FT-ICR MS platforms, 10 T LTQ FT from Thermo Scientific and 9.4 T SolariX XR from Bruker Daltonics. The cells provided accurate mass measurements in the analyses of singly and multiply charged peptides (root-mean-square, RMS, mass error Δm/m of 90 ppb), proteins (Δm/m = 200 ppb), and petroleum fractions (Δm/m < 200 ppb). Due to the reduced influence of measured frequency on the space charge and external (trapping) electric fields, the 2xNADEL ICR cells exhibited stable performance in a wide range of trapping potentials (1-20 V). Similarly, in a 13 h rat brain MALDI imaging experiment, the RMS mass error did not exceed 600 ppb even for low signal-to-noise ratio analyte peaks. Notably, the same set of calibration constants was applicable to Fourier spectra in all pixels, reducing the need for recalibration at the individual pixel level. Overall, these results support further experimental development and fundamentals investigation of this promising technology.

Over the past couple of years, imaging mass spectrometry (IMS) has arisen as a powerful tool to answer research questions in the biomedical field. Imaging mass spectrometry allows for label-free chemical imaging by providing full molecular information. The IMS technique best positioned for cell and tissue analysis is time-of-flight secondary ion mass spectrometry (ToF-SIMS) because it has the best spatial resolution of all the molecular IMS techniques and can detect many biochemical species and especially lipids with high sensitivity. Because one must rely on the mass and isotopic pattern of an ion in combination with positive correlations with lower mass fragments to help identify its structure, one major problem during ToF-SIMS experiments is the ambiguity when assigning a molecule to a certain mass peak. The solution are instruments with tandem MS capabilities as was already the case for many MALDI-ToF instruments more than a decade ago. It has been a few years since instruments with this capability were introduced and a number of interesting publications have been produced highlighting the advantages in biological SIMS work. Here, we present a protocol describing how tandem MS can be used to elucidate the structure of unknown or ambiguous mass peaks in biological tissue samples observed during ToF-SIMS imaging based on our experiences.

The material evidence for the wax finish on ancient marble statues, known as ganosis, is scarce and controversial, although Greek and Latin sources describe the recipes and cultural value of this treatment. The surface treatment of a colossal Roman head from the Roman theatre of Dougga (Tunisia), dated to the end of the second century CE, is studied by a multi-analytical protocol (video-microscope, cross section, and time-of-flight secondary ion mass spectrometry of one sample). The results of this physico-chemical analysis and the comparison with ancient recipes, prove the use of ganosis on a Roman statue and explore, for the first time, the application of the recipes described in ancient sources. This result shows the potential of the Time-of-Flight Secondary Ion Mass Spectrometry analysis, detecting at the same time organic and inorganic materials and their stratigraphy, to study the ancient recipes.

International audience; Pulmonary arterial hypertension (PAH) is a rare and deadly disease affecting roughly 15–60 people per million in Europe with a poorly understood pathology. There are currently no diagnostic tools for early detection nor does a curative treatment exist. The lipid composition of arteries in lung tissue samples from human PAH and control patients were investigated using matrix-assisted laser desorption ionization (MALDI) imaging mass spectrometry (IMS) combined with time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging. Using random forests as an IMS data analysis technique, it was possible to identify the ion at m/z 885.6 as a marker of PAH in human lung tissue. The m/z 885.6 ion intensity was shown to be significantly higher around diseased arteries and was confirmed to be a diacylglycerophosphoinositol PI(C18:0/C20:4) via MS/MS using a novel hybrid SIMS instrument. The discovery of a potential biomarker opens up new research avenues which may finally lead to a better understanding of the PAH pathology and highlights the vital role IMS can play in modern biomedical research.

Introduction Acetogenins are plant polyketides known to be cytotoxic and proposed as antitumor candidates. They are also suspected to be alimentary neurotoxins. Their occurrence as complex mixtures renders their dereplication and structural identification difficult using liquid chromatography coupled to tandem mass spectrometry and efforts are required to improve the methodology. Objective To develop a supercritical fluid chromatography (SFC) high-resolution tandem mass spectrometry method, involving lithium post-column cationisation, for the structural characterisation of Annonaceous acetogenins in crude extracts. Methodology The seeds of Annona muricata L. were extracted with methanol. Supercritical fluid chromatography of the extract, using a 2-ethylpyridine stationary phase column, was monitored using a high-resolution quadrupole time-of-flight mass spectrometer. Lithium iodide was added post-column in the make-up solvent. For comparison, the same extract was analysed using high-pressure liquid chromatography coupled to the same mass spectrometer, with a column based on solid core particles. Results Sensitivity was similar for both HPLC and SFC approaches. Retention behaviour and fragmentation pathways of three different isomer groups are described. A previously unknown group of acetogenins was also evidenced for the first time. Conclusion The use of SFC-MS/MS allows the reduction of the time of analysis, of environmental impact and an increase in the chromatographic resolution, compared to liquid chromatography. This new methodology enlightened a new group of acetogenins, isomers of montanacin-D. Copyright © 2017 John Wiley & Sons, Ltd.

International audience; The "3D­Plant2Cells" project investigates the impact of the agricultural mode on crops grown for human consumption. We are developing an innovative interdisciplinary approach to study the metabolome and the microbiota of plants in three­ dimension (3D) at three different scales: the whole plant, the fruit, and the cellular scales. The objective of this study is to get a new insight on the metabolome and microbiota response to pesticide treatment. The hypothesis is that the chemistry and microbiome could change upon the use of conventional cultivation managements. To explore this hypothesis, two groups of plants are cultivated in growth chamber and one receives pesticide treatments. The metabolome and the plant­ associated microbiota are explored on the whole plant surface (plant scale) by using an innovative interdisciplinary approach [1,2]. Samples are collected on the whole plant and their metabolite content profiled by high­resolution tandem­ mass spectrometry (HR­MS/MS) and plant­associated microorganism communities by amplicon sequence analysis (metagenomics) [1]. Results of these both inputs are compiled into a bioinformatic model representing a 3D topological map of the metabolome/microbiome over the entire organism surface [1]. Mass spectrometry data will be further interpreted using MS/MS molecular networking [1]. In the meantime, we are studying fruits of the cultivated specimens by 3D mass spectrometry imaging to study the metabolome/microbiota response to pesticide treatments along with the pesticide distribution in 3D. The fruit and cell scale are explored by analyzing serial sections using MALDI, nanoDESI, 3D­ TOF­SIMS coupled to HR­MS/MS. The presentation will aim at introducing the project, and to highlight some methodological approaches used to study the microbiota­chemistry relationships in species or ecosystem.

International audience; The Annonaceous acetogenin annonacin is an environmental neurotoxin identified in the pulp of several fruits of the Annonaceae family, whose consumption was linked to the occurrence of sporadic atypical Parkinsonism with dementia. A method for its quantification in Rat brain homogenates by UPLC-MS/MS in selected reaction monitoring (SRM) mode was developed and validated. This method was applied to the quantitation of annonacin in Rat brain after intravenous (0.5 mg/kg) and oral (10 mg/kg, 100 mg/kg) administration.

The preparation of tropical wood surface sections for time-of-flight secondary ion mass spectrometry imaging is described, and the use of delayed extraction of secondary ions and its interest for the analysis of vegetal surface are shown. The method has been applied to the study by time-of-flight secondary ion mass spectrometry imaging with a resolution of less than one micron of a tropical wood species, Dicorynia guianensis, which is one of the most exploited wood in French Guiana for its durable heartwood. The heartwood of this species exhibits an economical importance, but its production is not controlled in forestry. Results show an increase of tryptamine from the transition zone and a concomitant decrease of inorganic ions and starch fragment ions. These experiments lead to a better understanding of the heartwood formation and the origin of the natural durability of D. guianensis. Copyright © 2016 John Wiley & Sons, Ltd.

Molecular analysis by parallel tandem mass spectrometry (MS/MS) imaging contributes to the in situ characterization of biosynthetic intermediates which is crucial for deciphering the metabolic pathways in living organisms. We report the first use of TOF-SIMS MS/MS imaging for the cellular localization and characterization of biosynthetic intermediates of bioactive γ-lactones rubrynolide and rubrenolide in the Amazonian tree Sextonia rubra (Lauraceae). Five γ-lactones, including previously reported rubrynolide and rubrenolide, were isolated using a conventional approach and their structural characterization and localization at a lateral resolution of ~400 nm was later achieved using TOF-SIMS MS/MS imaging analysis. 2D/3D MS imaging at subcellular level reveals that putative biosynthetic γ-lactones intermediates are localized in the same cell types (ray parenchyma cells and oil cells) as rubrynolide and rubrenolide. Consequently, a revised metabolic pathway of rubrynolide was proposed, which involves the reaction between 2-hydroxysuccinic acid and 3-oxotetradecanoic acid, contrary to previous studies suggesting a single polyketide precursor. Our results provide insights into plant metabolite production in wood tissues and, overall, demonstrate that combining high spatial resolution TOF-SIMS imaging and MS/MS structural characterization offers new opportunities for studying molecular and cellular biochemistry in plants.

L’imagerie par spectrometrie de masse d’ions secondaires TOF-SIMS est une technique d’analyse de surface et de volume qui permet de localiser et identifier la composition chimique d’un echantillon sur une epaisseur de plusieurs microns. Elle donne acces aux composes organiques par la detection d’ions moleculaires et de fragments, et a la composition minerale, et n’est pas destructive. C’est donc une technique qui est de plus en plus utilisee pour l’analyse de prelevements de tableaux, en particulier des tableaux anciens. Cet article presentera, dans une premiere partie, les methodes de l’analyse TOF-SIMS et, dans une seconde partie, trois exemples d’analyses de tableaux anciens.

Abiotic hydrocarbons and carboxylic acids are known to be formed on Earth, notably during the hydrothermal alteration of mantle rocks. Although the abiotic formation of amino acids has been predicted both from experimental studies and thermodynamic calculations, its occurrence has not been demonstrated in terrestrial settings. Here, using a multimodal approach that combines high-resolution imaging techniques, we obtain evidence for the occurrence of aromatic amino acids formed abiotically and subsequently preserved at depth beneath the Atlantis Massif (Mid-Atlantic Ridge). These aromatic amino acids may have been formed through Friedel–Crafts reactions catalysed by an iron-rich saponite clay during a late alteration stage of the massif serpentinites. Demonstrating the potential of fluid-rock interactions in the oceanic lithosphere to generate amino acids abiotically gives credence to the hydrothermal theory for the origin of life, and may shed light on ancient metabolisms and the functioning of the present-day deep biosphere. High-resolution imaging techniques show that aromatic amino acids such as tryptophan formed abiotically and were subsequently preserved at depth beneath the Atlantis Massif of the Mid-Atlantic Ridge, supporting the hydrothermal theory for the origin of life.

For the most effective analytical strategies, development and validation include optimization of such analytical variables as resolution, detectability, sensitivity, simplicity, cost effectiveness, flexibility, and speed. However, other aspects concerning operator safety and environmental impact are not considered at the same level. The result has been many unintended negative effects of analytical methods developed to investigate different kinds of sample, especially hydrophobic compounds that generate a large amount of chemical waste and have a strong negative environmental impact. In this context, quantification of tocopherols and tocotrienols, i.e. the vitamin E family, is usually achieved by normal-phase liquid chromatography using large volumes of toxic organic solvents, or reversed-phase liquid chromatography using a high percentage of methanol for elution. We propose here a "greener" analytical strategy, including the hyphenation of supercritical-fluid chromatography, using CO2 and ethanol as mobile phase, NH2 as stationary phase, and mass spectrometry for the detection and quantification of vitamin E congeners in soybean oil. An atmospheric-pressure photoionization (APPI) source seemed significantly more sensitive and robust than electrospray or atmospheric-pressure chemical ionization (APCI). This method led to shortened analysis time (less than 5 min) and was revealed to be as sensitive as more traditional approaches, with limits of detection and quantification in the tens of μg L(-1).

Imaging mass spectrometry (IMS) has become a powerful tool to characterize the spatial distribution of biomolecules in thin tissue sections. In the case of matrix-assisted laser desorption ionization (MALDI) IMS, homogeneous matrix deposition is critical to produce high-quality ion images, and sublimation in particular has shown to be an excellent matrix deposition method for the imaging of lipids. Matrix deposition by sublimation is, however, a completely solvent-free system, which ought to prevent the mixing of matrix and analytes thought to be necessary for successful MALDI. Using 3D time-of-flight secondary ion imaging mass spectrometry, we have studied the matrix tissue interface in 3D with high resolution to understand the MALDI process of lipids after matrix deposition by sublimation. There is a strong indication that diffusion is the process by which lipids migrate from the tissue to the matrix layer. We show that triacylglycerols and phospholipids have a delayed migratory trend as compared to diacylglycerols and monoacylglycerols, which is dependent on time and matrix thickness. Additional experiments show that a pure lipid's capacity to migrate into the matrix is dependent on its fluidity at room temperature. Furthermore, it is shown that cholesterol can only migrate in the presence of a (fluid) lipid and appears to fluidize lipids, which could explain its colocalization with the diacylglycerols and monoacylglycerols in the matrix.

International audience; The emission/ionization process under massive argon cluster bombardment was investigated by measuring the internal energy distributions of a series of benzylpyridinium ions. Argon clusters with kinetic energies between 10 and 20keV and cluster sizes ranging from 500 to 10,000 were used to establish the influence of their size, energy, and velocity on the internal energy distribution of the secondary ions. It is shown that the internal energy distribution of secondary ions principally depends on the energy per atom or the velocity of the cluster ion beam (E/n v(2)). Under low energy per atom (E/n?10eV), the mean internal energy and fragmentation yield increase rapidly with the incident energy of individual constituents. Beyond 10eV/atom impact (up to 40eV/atom), the internal energy reaches a plateau and remains constant. Results were compared with those generated from bismuth cluster impacts for which the mean internal energies correspond well to the plateau values for argon clusters. However, a significant difference was found between argon and bismuth clusters concerning the damage or disappearance cross section. A 20 times smaller disappearance cross section was measured under 20keV Ar-2000(+) impact compared to 25keV Bi-5(+) bombardment, thus quantitatively showing the low damage effect of large argon clusters for almost the same molecular ion yield.

International audience; Driven by a necessity for confident molecular identification at high spatial resolution, a new time-of-flight secondary ion mass spectrometry (TOF-SIMS) tandem mass spectrometry (tandem MS) imaging instrument has been recently developed. In this paper, the superior MS/MS spectrometry and imaging capability of this new tool is shown for natural product study. For the first time, via in situ analysis of the bioactive metabolites rubrenolide and rubrenolide in Amazonian tree species Sextonia rubra (Lauraceae), we were able both to analyze and to image by tandem MS the molecular products of natural biosynthesis. Despite the low abundance of the metabolites in the wood sample(s), efficient MS/MS analysis of these gamma-lactone compounds was achieved, providing high confidence in the identification and localization. In addition, tandem MS imaging minimized the mass interferences and revealed specific localization of these metabolites primarily in the ray parenchyma cells but also in certain oil cells and, further, revealed the presence of previously unidentified gamma-lactone, paving the way for future studies in biosynthesis.

Wood extractives in the xylem of European larch Larix decidua were mapped by time-of-flight secondary ion mass spectrometry (TOF-SIMS) imaging, which allows the radial distribution of both mineral and lipophilic extractives in the xylem to be scrutinized with high spatial resolution for the first time. Results show that all the components are inhomogeneously distributed across the annual ring. Mineral nutrients including Na+, K+, Ca+, and Cl− ions exhibit no preferential localization between earlywood and latewood, whereas PO3− ion is exclusively present in the ray cells, indicating it may be related to acid phosphatase. Lipophilic extractives were found to be more abundant in the inner secondary xylem. Ion images with 400 nm spatial resolution reveal that fatty acids, triglycerides and phytosterols are co-localized principally in the earlywood within the first annual ring. Resin acids prove to be the main components in the resin canal of the secondary xylem and are distributed in the outer of it.

A supercritical fluid chromatography-based targeted purification procedure using tandem mass spectrometry and molecular networking was developed to analyze, annotate, and isolate secondary metabolites from complex plant extract mixture. This approach was applied for the targeted isolation of new antiviral diterpene esters from Euphorbia semiperfoliata whole plant extract. The analysis of bioactive fractions revealed that unknown diterpene esters, including jatrophane esters and phorbol esters, were present in the samples. The purification procedure using semipreparative supercritical fluid chromatography led to the isolation and identification of two new jatrophane esters (13 and 14) and one known (15) and three new 4-deoxyphorbol esters (16–18). The structure and absolute configuration of compound 16 were confirmed by X-ray crystallography. This compound was found to display antiviral activity against Chikungunya virus (EC50 = 0.45 μM), while compound 15 proved to be a potent and selective inhibitor of H...

Natural oils are commonly used in topical pharmaceutical formulations as emulsifiers, stabilizers or solubility enhancers. They are presented as safe and inert components, mainly used for formulation purposes. It is confirmed that natural oils can affect the skin penetration of various substances. Fatty acids are mainly responsible for this effect. Current understanding lacks reliable scientific data on penetration of natural oils into the skin and their skin penetration enhancement potential. In the current study, fatty acid content analysis was used to determine the principal fatty acids in soybean, olive, avocado, sea-buckthorn pulp, raspberry seed and coconut oils. Time of flight secondary ion mass spectrometry bioimaging was used to determine the distribution of these fatty acids in human skin ex vivo after application of the oils. Skin penetration enhancement ratios were determined for a perspective antioxidant compound dihydroquercetin. The results demonstrated skin penetration of fatty acids from all oils tested. Only soybean and olive oils significantly increased the skin distribution of dihydroquercetin and can be used as skin penetration enhancers. However, no correlation can be determined between the fatty acids’ composition and skin penetration enhancement using currently available methodological approaches. This indicates that potential chemical penetration enhancement should be evaluated during formulation of topically applied products containing natural oils.

Rationale Mass spectrometry imaging (MSI) is a powerful tool for mapping the surface of a sample. Time-of-flight secondary ion mass spectrometry (TOF-SIMS) and atmospheric pressure matrix-assisted laser desorption/ionization (AP-MALDI) offer complementary capabilities. Here, we present a workflow to apply both techniques to a single tissue section and combine the resulting data for the example of human colon cancer tissue. Methods Following cryo-sectioning, images were acquired using the high spatial resolution (1 μm pixel size) provided by TOF-SIMS. The same section was then coated with a para-nitroaniline matrix and images were acquired using AP-MALDI coupled to an Orbitrap mass spectrometer, offering high mass resolution, high mass accuracy and tandem mass spectrometry (MS/MS) capabilities. Datasets provided by both mass spectrometers were converted into the open and vendor-independent imzML file format and processed with the open-source software MSiReader. Results The TOF-SIMS and AP-MALDI mass spectra show strong signals of fatty acids, cholesterol, phosphatidylcholine and sphingomyelin. We showed a high correlation between the fatty acid ions detected with TOF-SIMS in negative ion mode and the phosphatidylcholine ions detected with AP-MALDI in positive ion mode using a similar setting for visualization. Histological staining on the same section allowed the identification of the anatomical structures and their correlation with the ion images. Conclusions This multimodal approach using two MSI platforms shows an excellent complementarity for the localization and identification of lipids. The spatial resolution of both systems is at or close to cellular dimensions, and thus spatial correlation can only be obtained if the same tissue section is analyzed sequentially. Data processing based on imzML allows a real correlation of the imaging datasets provided by these two technologies and opens the way for a more complete molecular view of the anatomical structures of biological tissues.

Using a time-of-flight secondary ion mass spectrometer equipped with an argon cluster ion for sputtering and a bismuth liquid metal ion source for analysis, both surfaces of leaves and fruits of Macaranga vedeliana, an endemic New Caledonian species, have been for the first time analyzed by a dual beam depth profiling. To prevent in-vacuum evaporation of the liquid content of the small glandular trichomes covering fruits and leaves surfaces and also to be able to analyze their liquid content while preventing any sublimation of the latter, the samples were kept frozen during the whole experiment using a nitrogen cooled sample holder. Thus, it was possible to demonstrate that vedelianin, an active metabolite of the family of prenylated stilbenes named schweinfurthins, is only located in these glandular trichomes.

Nonalcoholic steatohepatitis (NASH) is a condition which can progress to cirrhosis and hepatocellular carcinoma. Markers for NASH diagnosis are still lacking. We performed a comprehensive lipidomic analysis on human liver biopsies including normal liver, nonalcoholic fatty liver and NASH. Random forests-based machine learning approach allowed characterizing a signature of 32 lipids discriminating NASH with 100% sensitivity and specificity. Furthermore, we validated this signature in an independent group of NASH patients. Then, metabolism dysregulations were investigated in both patients and murine models. Alterations of elongase and desaturase activities were observed along the fatty acid synthesis pathway. The decreased activity of the desaturase FADS1 appeared as a bottleneck, leading upstream to an accumulation of fatty acids and downstream to a deficiency of long-chain fatty acids resulting to impaired phospholipid synthesis. In NASH, mass spectrometry imaging on tissue section revealed the spreading into the hepatic parenchyma of selectively accumulated fatty acids. Such lipids constituted a highly toxic mixture to human hepatocytes. In conclusion, this study characterized a specific and sensitive lipid signature of NASH and positioned FADS1 as a significant player in accumulating toxic lipids during NASH progression.

The development of ‘omics’ sciences offers new opportunities for the study of neurodegenerative diseases but increases at the same time the sample demand on brain banks that collect and store valuable human post-mortem tissue. Our study aims to evaluate in lipidomics the potential of formalin-fixed tissue compared with the cryopreservation method, considered as the gold standard for biochemical research. Two complementary liquid chromatography/mass spectrometry analytical platforms were used on the basis of hybrid quadrupole time-of-flight and triple quadrupole mass spectrometers. Untargeted fingerprinting, semitargeted profiling of specific lipid classes and targeted monitoring of lipid species were performed in formalin-fixed and cryopreserved samples to provide detailed information at the molecular level on the formalin-induced alterations of the brain tissue. In vitro incubations of lipid standards were also performed to further describe the degradation processes induced by formaldehyde. Phospholipid compounds were found to be extensively hydrolysed, whilst the sphingolipid ones were preserved. N-methylation and N-formylation of amine-containing phospholipids have also been evidenced. These findings show that the potential detrimental effect of formalin on the analytes of interest must be taken into account when analysing formalin-fixed samples. Copyright © 2014 John Wiley & Sons, Ltd.

International audience; Epidemiological and toxicological studies have suggested Annonaceaeous acetogenins to be environmental neurotoxins responsible for sporadic atypical parkinsonism/dementia in tropical areas. These compounds are present in the tropical genus Annona (Annonaceae), known for its fruit-yielding cultivated species such as Annona cherimolia. This species is widely cultivated in South America, Spain, and Portugal and yields acetogenins in its seeds, stems, and roots. The presence of these compounds in the pulp of its fruit and in derived food products is unclear. An innovative and sensitive methodology by HPLC-ESI-LTQ-Orbitrap with postcolumn infusion of lithium iodide was used to identify the presence of low levels of acetogenins in an A. cherimolia Mill. fruit-based commercial alcoholic beverage. More than 80 representatives were detected, and the 31 most intense acetogenins were identified. All together these findings indicate that this species should be considered as a risk factor within the framework of a worldwide problem of food toxicity.

International audience; Lipid disorders have been associated with glomerulopathies, a distinct type of renal pathologies, such as nephrotic syndrome. Global analyses targeting kidney lipids in this pathophysiologic context have been extensively performed, but most often regardless of the architectural and functional complexity of the kidney. The new developments in mass spectrometry imaging technologies have opened a promising field in localized lipidomic studies focused on this organ. In this article, we revisit the main works having employed the Matrix Assisted Laser Desorption Ionization Time of Flight (MALDI-TOF) technology, and the few reports on the use of TOF-Secondary Ion Mass Spectrometry (TOF-SIMS). We also present a first analysis of mouse kidney cortex sections by cluster TOF-SIMS. The latter represents a good option for high resolution lipid imaging when frozen unfixed histological samples are available. The advantages and drawbacks of this developing field are discussed.

Studies of the chemical composition of organs using mass spectrometry imaging become an important issue to better understand the mechanisms involved in various diseases. Biologists not only focus on the detection and characterization of compounds of interest but also on the reliability of the method. Time-of-flight secondary ion mass spectrometry (TOF-SIMS), which is already known to offer an excellent repeatability in material sciences, is also a method of choice for the detection and mapping of small molecules in biological samples. Ions corresponding to different types of lipids such as the fatty acid chains, cholesterol and vitamin E were studied in gyrus dentatus and cortex of rat brain sections. The analysis of the repeatability of the data was conducted, and a global coefficient of variation of about 10% was found. It thus confirms that TOF-SIMS studies can be considered as an accurate analytical method for the study of biological samples.

A supercritical fluid chromatography-based targeted purification workflow using tandem mass spectrometry and molecular networking was developed to analyze, annotate and isolate secondary metabolites from complex mixture. This approach was applied for targeted isolation of new antiviral diterpene esters from Euphorbia semiperfoliata whole plant extract. The analysis of bioactive fractions revealed that unknown diterpene esters, including jatrophane esters and phorboids esters, were present in the samples. The purification procedure using semi-preparative-supercritical fluid chromatography led to the isolation and identification of two jatrophane esters (13 and 14) and four 4-deoxyphorbol esters (15-18). Compound 16 was found to display antiviral activity against chikungunya virus (EC50 = 0.45 µM), while compound 15 was found to be a potent and selective inhibitor of HIV-1 replication in a recombinant virus assay (EC50 = 13 nM). This study showed that supercritical fluid chromatography-based workflow and molecular networking can facilitate and accelerate the discovery of bioactive small molecules by targeted molecules of interest, while minimizing the use of toxic solvents.

International audience; An integrative approach combining traditional natural products chemistry, molecular networking, and mass spectrometry imaging has been undertaken to decipher the molecular dialogue between the fungus Paraconiothyrium variabile and the bacterium Bacillus subtilis, which were isolated as endophytes from the conifer Cephalotaxus harringtonia and are characterized by a strong and mutual antibiosis. From this study, we highlight that bacterial surfactins and a fungal tetronic acid are involved in such competition and that the fungus is able to hydrolyze surfactins to fight against the bacterial partner.

The painting Rebecca and Eliezer at the Well, which hangs in the Fitzwilliam Museum, Cambridge, UK, is possibly one of the last figure painting executed by Nicolas Poussin at the very end of his life and is usually dated to the early 1660s. In this perspective special feature, Philippe Walter, Alain Brunelle and colleagues give new insights on the artist's working methods by a careful stateof-the-art imaging ToF-SIMS study of one sample taken on the edge of the painting. This approach allowed for the identification of the pigments used in the painting, their nature and components and those of the ground and preparatory layers, with the identification of the binder(s) and possible other additions of organic materials such as glue. This study paves the way to a wider use of ToF-SIMS for the analysis of ancient cultural heritage artefacts. Dr. Walter is the Director of the Molecular and Structural Archeology Laboratory (Universite Pierre et Marie Curie, Paris, France). Dr. Brunelle is Head of the Mass Spectrometry Laboratory at the Institut de Chimie des Substances Naturelles (CNRS, Gif-sur-Yvette, France). Their long standing collaboration has led to several seminal publications on the analysis of ancient artefacts by mass spectrometry.

Acetogenins are plant polyketides known to be cytotoxic and proposed as antitumor candidates. They are also suspected to be alimentary neurotoxins. Their occurrence as complex mixtures renders their dereplication and structural identification difficult using liquid chromatography coupled to tandem mass spectrometry and efforts are required to improve the methodology.To develop a supercritical fluid chromatography (SFC) high-resolution tandem mass spectrometry method, involving lithium post-column cationisation, for the structural characterisation of Annonaceous acetogenins in crude extracts.The seeds of Annona muricata L. were extracted with methanol. Supercritical fluid chromatography of the extract, using a 2-ethylpyridine stationary phase column, was monitored using a high-resolution quadrupole time-of-flight mass spectrometer. Lithium iodide was added post-column in the make-up solvent. For comparison, the same extract was analysed using high-pressure liquid chromatography coupled to the same mass spectrometer, with a column based on solid core particles.Sensitivity was similar for both HPLC and SFC approaches. Retention behaviour and fragmentation pathways of three different isomer groups are described. A previously unknown group of acetogenins was also evidenced for the first time.The use of SFC-MS/MS allows the reduction of the time of analysis, of environmental impact and an increase in the chromatographic resolution, compared to liquid chromatography. This new methodology enlightened a new group of acetogenins, isomers of montanacin-D. Copyright © 2017 John WileySons, Ltd.

Annonaceous acetogenins (AAGs) are a homogenous class of polyketides proposed as environmental neurotoxins. Previous dereplication studies of AAGs were limited by the use of low-resolution mass spectrometers. Only poor information in terms of structures was provided due to the limited fragmentation of protonated or sodium cationized species. An innovative approach, using reversed-phase high-performance liquid chromatography coupled to a hybrid linear ion trap / orbitrap mass spectrometer (LTQ-Orbitrap®), was therefore performed. Sensitivity was enhanced by post-column infusion of lithium, since AAGs have a high affinity for this cation. High level of structural information was obtained from low-energy-collision-induced dissociation fragmentation experiments of lithium-cationized AAGs ([M + Li](+) ions) as demonstrated with purified standards. The method was then applied to a total ethyl-acetate extract prepared from commercial soursop nectar (Annona muricata L.). The sensitivity, mass accuracy and specific fragmentation patterns proved to be particularly useful for characterization of the AAGs. Typical structural identification procedure and unexpected observations for specific structural types are illustrated, with major and minor compounds. Copyright © 2012 John Wiley & Sons, Ltd.

International audience; Background: Lipidomic studies related to Alzheimer's disease have been reported on either biological fluids or large human brain samples. For a better understanding of the role of lipids, especially during the amyloid-β peptide aggregation, it is crucial to determine the composition of the senile plaque versus the surrounding tissue, that is, the neuropil. Results: A laser microdissection step was added to the analysis by UPLC-MS/MS. Despite the very low amount of sample, two phosphatidylcholines that were significantly depleted in the senile plaque were identified. Conclusion: Changes in the phospholipid content have been shown between senile plaque versus neuropil. Nano HPLC, allowing a complete lipidomic profile, should further improve the results.