Targeted and untargeted quantification of quorum sensing signalling molecules in bacterial cultures and biological samples via HPLC-TQ MS techniques.

Quorum sensing (QS) is the ability of some bacteria to detect and to respond to population density through signalling molecules. QS molecules are involved in motility and cell aggregation mechanisms in diseases such as sepsis. Few biomarkers are currently available to diagnose sepsis, especially in high-risk conditions. The aim of this study was the development of new analytical methods based on liquid chromatography-mass spectrometry for the detection and quantification of QS signalling molecules, including N-acyl homoserine lactones (AHL) and hydroxyquinolones (HQ), in biofluids. Biological samples used in the study were Pseudomonas aeruginosa bacterial cultures and plasma from patients with sepsis. We developed two MS analytical methods, based on neutral loss (NL) and product ion (PI) experiments, to identify and characterize unknown AHL and HQ molecules. We then established a multiple-reaction-monitoring (MRM) method to quantify specific QS compounds. We validated the HPLC-MS-based approaches (MRM-NL-PI), and data were in accord with the validation guidelines. With the NL and PI MS-based methods, we identified and characterized 3 and 13 unknown AHL and HQ compounds, respectively, in biological samples. One of the newly found AHL molecules was C12-AHL, first quantified in Pseudomonas aeruginosa bacterial cultures. The MRM quantitation of analytes in plasma from patients with sepsis confirmed the analytical ability of MRM for the quantification of virulence factors during sepsis. Graphical abstract.

Impacts of NRF2 activation in non-small-cell lung cancer cell lines on extracellular metabolites.

Aberrant activation of NRF2 is as a critical prognostic factor that drives the malignant progression of various cancers. Cancer cells with persistent NRF2 activation heavily rely on NRF2 activity for therapeutic resistance and aggressive tumorigenic capacity. To clarify the metabolic features of NRF2-activated lung cancers, we conducted targeted metabolomic (T-Met) and global metabolomic (G-Met) analyses of non-small-cell lung cancer (NSCLC) cell lines in combination with exome and transcriptome analyses. Exome analysis of 88 cell lines (49 adenocarcinoma, 14 large cell carcinoma, 15 squamous cell carcinoma and 10 others) identified non-synonymous mutations in the KEAP1, NRF2 and CUL3 genes. Judging from the elevated expression of NRF2 target genes, these mutations are expected to result in the constitutive stabilization of NRF2. Out of the 88 cell lines, 52 NSCLC cell lines (29 adenocarcinoma, 10 large cell carcinoma, 9 squamous cell carcinoma and 4 others) were subjected to T-Met analysis. Classification of the 52 cell lines into three groups according to the NRF2 target gene expression enabled us to draw typical metabolomic signatures induced by NRF2 activation. From the 52 cell lines, 18 NSCLC cell lines (14 adenocarcinoma, 2 large cell carcinoma, 1 squamous cell carcinoma and 1 others) were further chosen for G-Met and detailed transcriptome analyses. G-Met analysis of their culture supernatants revealed novel metabolites associated with NRF2 activity, which may be potential diagnostic biomarkers of NRF2 activation. This study also provides useful information for the exploration of new metabolic nodes for selective toxicity towards NRF2-activated NSCLC.

Liquid chromatography/mass spectrometry analytical determination of gabapentin transformation products by heterogeneous photocatalysis and environmental evaluation.

RATIONALE: Gabapentin is a drug used to treat epilepsy and peripheral neuropathic pain. It is an analog of gamma-aminobutyric acid, and it is a selective blocker of voltage-gated calcium channels. The drug is excreted unmetabolized; it is stable in the environment and is classified as a persistent mobile organic contaminant. Because wastewater treatment plants (WWTPs) are not completely efficient, some bioactive molecules may be released unaltered into the environment. The aim of this study was to provide information about degradation pathways of gabapentin in water by studying its photoinduced transformation products (TPs) through laboratory simulation experiments. Gabapentin and its TPs were monitored in influent and effluent water samples from WWTPs in Germany and Italy. METHODS: The laboratory simulation used heterogeneous photodegradation mediated by titanium dioxide (TiO2 ). Chromatographic separation was achieved using a C18 reverse-phase column, and the structural identification of TPs was performed using high-resolution electrospray ionization high-resolution mass spectrometry (ESI-HRMS) and multistage MSn experiments. RESULTS: Several TPs were observed during TiO2 photodegradation. Nine new compounds were detected, and potential structures were assigned by studying the fragmentation pathways of the [M + H]+ ions of these TPs and gabapentin. Gabapentin and some of the newly identified TPs were found in environmental samples from WWTPs. CONCLUSIONS: The developed high-performance liquid chromatography/high-resolution mass spectrometry method was used to identify TPs from gabapentin. It was then successfully applied to real environmental samples to monitor the TPs as potential environmental pollutants.

Identification of Polyphenolic Compounds in Edible Wild Fruits Grown in the North-West of Italy by Means of HPLC-DAD-ESI HRMS.

The popularity of edible wild fruits has increased in industrialized countries due to their composition and positive effects. The aim of this study has been to characterize the polyphenolics and anthocyanins of black mulberry (Morus nigra L.), cornelian cherry (Cornus mas L.), elderberry (Sambucus nigra L.), hawthorn (Crataegus monogyna L.), lingonberry (Vaccinium vitis-idaea L.) and rose hip (Rosa canina L.) harvested in the north-west of Italy by means of HPLC-DAD-ESI HRMS in positive ion mode. Although there is an abundant amount of literature related to the polyphenolics of cultivated fruit, a new type of comparison has here been conducted between wild and cultivated fruits on their polyphenolic content. The HPLC-DAD-ESI HRMS method has detected 64 different polyphenolic molecules and it can be used to perform qualitative and quantitative analyses. Furthermore, the cornelian cherry and elderberry samples showed the highest polyphenolic compound levels. The quercetin glycosylated compounds showed the highest percentage of flavonols in most of the analyzed wild fruits.

Characterization of alkaloids in bark extracts of Geissospermum vellosii by HPLC-UV-diode array-multistage high-resolution mass spectrometry.

A number of analytical studies, started in the sixties of the last century, concerning the stem bark of Geissospermum vellosii, have documented the presence of a number of indole alkaloids whose molecular identity was defined by NMR technique. The potential bioactivity of these compounds has inspired more recent analogous studies either devoted to structural elucidation of new alkaloid molecules or to the investigation of the role of some of them in cancer therapy. Anyway, a complete fingerprinting of the bark content is still lacking. In this paper, after a suitable extraction step, we obtain a chromatographic separation showing a number of components higher than the number of alkaloids so far described. Considering the great number of substances present in the stem bark, their identification is practically impossible to reveal by NMR techniques. As we presume that there are other stem bark unidentified alkaloids with important bioactivity, we propose to characterize their molecular structures by UV-Vis Diode Array spectrophotometry and High-Resolution Multistage Mass Spectrometry. The two adopted detection techniques were first tested on the already known Geissospermum vellosii molecules, and, after an inspection of their efficacy, were applied to the substances that have not yet been described. Herewith we propose the molecular structures of 10 substances that were never previously described, and in addition we provide experimental evidence of the presence of 6 already known substances which were never reported in the Geissospermum genus. A far more detailed description of the bark constituents is therefore provided.

Bisphenol A and S in the Urine of Newborns: Plastic for Non-Food Use Still without Rules.

The aim of the present study was to assess the effects of bisphenol (BP) exposure on pregnancy and neonatal life. We have (a) determined BP (BPA and BPS) concentration levels in a group of newborns and their mothers; (b) identified factors, habits, and devices possibly responsible for BP uptake; and (c) determined the effect of BP exposure. No significant correlations were detected between maternal and neonatal BP concentration levels. In newborns, positive correlations between pacifier use and BPS total (p = 0.04) and free BPS (p = 0.03) concentrations were detected. A significant correlation was also found between oral glucose administration and concentration levels of free BPA (p < 0.05). Our study points to a central role of lifestyle, hospital procedures, and neonatal devices in inducing BP exposure, especially during the perinatal period. This is the first report of BP contamination in newborns due to widely non-alimentary products designed for newborn care, such as glucose-solution containers for BPA and pacifiers for BPS. Further studies are advocated in order to clarify both the impact of other BP forms on human health and development, as well as potential BPA exposure sources during neonatal and childhood life.

HPLC-HRMS Global Metabolomics Approach for the Diagnosis of "Olive Quick Decline Syndrome" Markers in Olive Trees Leaves.

Olive quick decline syndrome (OQDS) is a multifactorial disease affecting olive plants. The onset of this economically devastating disease has been associated with a Gram-negative plant pathogen called Xylella fastidiosa (Xf). Liquid chromatography separation coupled to high-resolution mass spectrometry detection is one the most widely applied technologies in metabolomics, as it provides a blend of rapid, sensitive, and selective qualitative and quantitative analyses with the ability to identify metabolites. The purpose of this work is the development of a global metabolomics mass spectrometry assay able to identify OQDS molecular markers that could discriminate between healthy (HP) and infected (OP) olive tree leaves. Results obtained via multivariate analysis through an HPLC-ESI HRMS platform (LTQ-Orbitrap from Thermo Scientific) show a clear separation between HP and OP samples. Among the differentially expressed metabolites, 18 different organic compounds highly expressed in the OP group were annotated; results obtained by this metabolomic approach could be used as a fast and reliable method for the biochemical characterization of OQDS and to develop targeted MS approaches for OQDS detection by foliage analysis.

Bioactive Compounds and Antioxidant Capacity of Small Berries.

The popularity of small berries has rapidly increased in Western countries given their antioxidant, anti-inflammatory, and antimicrobial activities and health-promoting properties. The aim of this study was to compare the fatty acid (FA) profile, phenolic compounds, and antioxidant capacity of extracts of 11 berries cultivated in the North West of Italy. Berry samples were extracted and evaluated for FA profile and total anthocyanin (TAC), total flavonoid contents (TFC), ferric-reducing antioxidant power (FRAP), and for their radical scavenging activities against 2,2'-diphenyl-1-picrylhydrazyl (DPPH•) radical. The main polyphenols of berry extracts were characterized by HPLC-DAD-UV-ESI HRMS in positive ion mode. Results showed that the highest TAC and TFC contents were recorded in black currants, blackberries, and blueberries. Maximum and minimum DPPH• radical scavenging activities, Trolox Equivalent Antioxidant Capacity, and FRAP measurements confirmed the same trend recorded for TAC and TFC values. HPLC-HRMS analyses highlight how blueberries and blackberries have the highest concentration in polyphenols. Palmitic, stearic, oleic, linoleic, α-linolenic, and γ-linolenic acids significantly differ between berries, with oleic and α-linolenic acid representing the most abundant FAs in raspberries. Among the berries investigated, results of phytochemical characterization suggest choosing black currants and blueberries as an excellent source of natural antioxidants for food and health purposes.

Multi-Analyte MS Based Investigation in Relation to the Illicit Treatment of Fish Products with Hydrogen Peroxide.

Fishery products are perishable due to the action of many enzymes, both endogenous and exogenous. The latter are produced by bacteria that may contaminate the products. When fishes age, there is a massive bacteria growth that causes the appearance of off-flavor. In order to obtain "false" freshness of fishery products, an illicit treatment with hydrogen peroxide is reported to be used. Residues of hydrogen peroxide in food may be of toxicology concern. We developed two mass spectrometry based methodologies to identify and quantify molecules related to the treatment of fishes with hydrogen peroxide. With ultra-high-performance liquid chromatography-mass spectrometry (UHPLC-MS) we evaluated the concentration of trimethylamine-N-oxide (TMAO), trimethylamine (TMA), dimethylamine (DMA), and cadaverine (CAD) in fish products. After evaluating LOQ, we measured and validated the lower limits of quantification (LLOQs as first levels of calibration curves) values of 50 (TMAO), 70 (TMA), 45 (DMA), and 40 (CAD) ng/mL. A high ratio between TMAO and TMA species indicated the freshness of the food. With a GC-MS method we confirmed the illicit treatment measuring the levels of H2O2 after an analytical reaction with anisole to give 2-hydroxyanisole as a marker. This latter product was detected in the headspace of the homogenized sample with simplification of the work-up. A LLOQ of 50 ng/mL was checked and validated. When fish products were whitened and refreshed with hydrogen peroxide, the detected amount of the product 2-hydroxyanisole could be very important, (larger than 100 mg/kg). The developed analytical methods were suitable to detect the illicit management of fishery products with hydrogen peroxide; they resulted as sensitive, selective, and robust.

Author Correction: Nrf2 contributes to the weight gain of mice during space travel.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Nrf2 contributes to the weight gain of mice during space travel.

Space flight produces an extreme environment with unique stressors, but little is known about how our body responds to these stresses. While there are many intractable limitations for in-flight space research, some can be overcome by utilizing gene knockout-disease model mice. Here, we report how deletion of Nrf2, a master regulator of stress defense pathways, affects the health of mice transported for a stay in the International Space Station (ISS). After 31 days in the ISS, all flight mice returned safely to Earth. Transcriptome and metabolome analyses revealed that the stresses of space travel evoked ageing-like changes of plasma metabolites and activated the Nrf2 signaling pathway. Especially, Nrf2 was found to be important for maintaining homeostasis of white adipose tissues. This study opens approaches for future space research utilizing murine gene knockout-disease models, and provides insights into mitigating space-induced stresses that limit the further exploration of space by humans.

Formation of by-products during chemical interesterification of lipids. Detection and characterization of dialkyl ketones by non-aqueous reversed-phase liquid chromatography-high resolution mass spectrometry and gas chromatography-mass spectrometry.

A new class of foreign substances present in the unsaponifiable fraction of vegetable oils undergone to chemical interesterification was systematically investigated. Their chemical structure, corresponding to dialkyl ketones (DAK) molecules, was elucidated both by gas chromatography-mass spectrometry (GC-MS), and liquid chromatography-high resolution mass spectrometry (LC-HRMS). An analytical protocol aimed to qualitative and quantitative detection of DAK molecules in vegetable oils of confectionery industry interest was developed. Being the range of concentration levels to be evaluated dependent on the technological task of interesterification process, the quantitation step was thoroughly examined. All the validation parameters were satisfactory and particularly the concentration determinations were made more reliable by the contemporary use of several quantitation standards. GC-MS and LC-HRMS analytical techniques exhibited comparable performances even if the second one shown better detection sensitivity.