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Open AccessCommunication Utilization of High Performance Liquid Chromatography Coupled to Tandem Mass Spectrometry for Characterization of 8-O-methylbostrycoidin Production by Species of the Fungus Fusarium

by Mark Busman

J. Fungi 2017, 3(3), 43; doi:10.3390/jof3030043

Received: 1 June 2017 / Revised: 14 July 2017 / Accepted: 20 July 2017 / Published: 25 July 2017

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Abstract

The pigment 8-O-methylbostrycoidin is a polyketide metabolite produced by multiple species of the fungus Fusarium that infects plant crops, including maize. A technique was developed for the analysis of 8-O-methylbostrycoidin by high performance liquid chromatography coupled to electrospray ionization

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The pigment 8-O-methylbostrycoidin is a polyketide metabolite produced by multiple species of the fungus Fusarium that infects plant crops, including maize. A technique was developed for the analysis of 8-O-methylbostrycoidin by high performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The quantitative nature of the LC-MS/MS experiment was demonstrated over a range of concentrations in maize. Limits of detection for the method (10 ng/g from 8-O-methylbostrycoidin spiked into ground maize) were shown, and susceptibility of the method to matrix effects from maize was also evaluated. The method was applied to evaluate the ability of the maize pathogen Fusarium verticillioides to produce 8-O-methylbostrycoidin in developing maize ears grown in an agricultural field. Full article

(This article belongs to the Special Issue Fungal Pigments)

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Open AccessArticle Development of an Automated Method for Selected Aromas of Red Wines from Cold-Hardy Grapes Using Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry-Olfactometry

by Lingshuang Cai, Somchai Rice, Jacek A. Koziel and Murlidhar Dharmadhikari

Separations 2017, 4(3), 24; doi:10.3390/separations4030024

Received: 1 June 2017 / Revised: 15 June 2017 / Accepted: 30 June 2017 / Published: 5 July 2017

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Abstract

The aroma profile of red wine is complex and research focusing on aroma compounds and their links to viticultural and enological practices is needed. Current research is limited to wines made from cold-hardy cultivars (interspecific hybrids of vinifera and native N. American grapes).

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The aroma profile of red wine is complex and research focusing on aroma compounds and their links to viticultural and enological practices is needed. Current research is limited to wines made from cold-hardy cultivars (interspecific hybrids of vinifera and native N. American grapes). The objective of this research was to develop a fully automated solid phase microextraction (SPME) method, using tandem gas chromatography-mass spectrometry (GC-MS)-olfactometry for the simultaneous chemical and sensory analysis of volatile/semi-volatile compounds and aroma in cold-hardy red wines. Specifically, the effects of SPME coating selection, extraction time, extraction temperature, incubation time, sample volume, desorption time, and salt addition were studied. The developed method was used to determine the aroma profiles of seven selected red wines originating from four different cold-hardy grape cultivars. Thirty-six aroma compounds were identified from Maréchal Foch, St. Croix, Frontenac, Vincent, and a Maréchal Foch/Frontenac blend. Among these 36 aroma compounds, isoamyl alcohol, ethyl caproate, benzeneethanol, ethyl decanoate, and ethyl caproate are the top five most abundant aroma compounds. Olfactometry helps to identify compounds not identified by MS. The presented method can be useful for grape growers and wine makers for the screening of aroma compounds in a wide variety of wines and can be used to balance desired wine aroma characteristics. Full article

(This article belongs to the Special Issue Trends in Microextraction Techniques for Sample Preparation)

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Open AccessArticle Semi-Quantitative Mass Spectrometry in AML Cells Identifies New Non-Genomic Targets of the EZH2 Methyltransferase

by Yordan Sbirkov, Colin Kwok, Amandeep Bhamra, Andrew J. Thompson, Veronica Gil, Arthur Zelent and Kevin Petrie

Int. J. Mol. Sci. 2017, 18(7), 1440; doi:10.3390/ijms18071440

Received: 10 June 2017 / Revised: 27 June 2017 / Accepted: 29 June 2017 / Published: 5 July 2017

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Abstract

Alterations to the gene encoding the EZH2 (KMT6A) methyltransferase, including both gain-of-function and loss-of-function, have been linked to a variety of haematological malignancies and solid tumours, suggesting a complex, context-dependent role of this methyltransferase. The successful implementation of molecularly targeted therapies against EZH2

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Alterations to the gene encoding the EZH2 (KMT6A) methyltransferase, including both gain-of-function and loss-of-function, have been linked to a variety of haematological malignancies and solid tumours, suggesting a complex, context-dependent role of this methyltransferase. The successful implementation of molecularly targeted therapies against EZH2 requires a greater understanding of the potential mechanisms by which EZH2 contributes to cancer. One aspect of this effort is the mapping of EZH2 partner proteins and cellular targets. To this end we performed affinity-purification mass spectrometry in the FAB-M2 HL-60 acute myeloid leukaemia (AML) cell line before and after all-trans retinoic acid-induced differentiation. These studies identified new EZH2 interaction partners and potential non-histone substrates for EZH2-mediated methylation. Our results suggest that EZH2 is involved in the regulation of translation through interactions with a number of RNA binding proteins and by methylating key components of protein synthesis such as eEF1A1. Given that deregulated mRNA translation is a frequent feature of cancer and that eEF1A1 is highly expressed in many human tumours, these findings present new possibilities for the therapeutic targeting of EZH2 in AML. Full article

(This article belongs to the Special Issue The Biology and Treatment of Myeloid Leukaemias)

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Open AccessArticle Tear Film Steroid Profiling in Dry Eye Disease by Liquid Chromatography Tandem Mass Spectrometry

by Damiana Pieragostino, Luca Agnifili, Ilaria Cicalini, Roberta Calienno, Mirco Zucchelli, Leonardo Mastropasqua, Paolo Sacchetta, Piero Del Boccio and Claudia Rossi

Int. J. Mol. Sci. 2017, 18(7), 1349; doi:10.3390/ijms18071349

Received: 28 April 2017 / Revised: 13 June 2017 / Accepted: 22 June 2017 / Published: 24 June 2017

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Abstract

Dry eye disease (DED) is a multifactorial disorder of the ocular surface unit resulting in eye discomfort, visual disturbance, and ocular surface damage; the risk of DED increases with age in both sexes, while its incidence is higher among females caused by an

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Dry eye disease (DED) is a multifactorial disorder of the ocular surface unit resulting in eye discomfort, visual disturbance, and ocular surface damage; the risk of DED increases with age in both sexes, while its incidence is higher among females caused by an overall hormonal imbalance. The role of androgens has recently investigated and these hormones were considered to have a protective function on the ocular surface. In order to correlate DED to tear steroid levels, a robust, specific, and selective method for the simultaneous quantification of cortisol (CORT), corticosterone (CCONE), 11-deoxycortisol (11-DECOL), 4-androstene-3,17-dione (ADIONE), testosterone (TESTO), 17α-hydroxyprogesterone (17-OHP), and progesterone (PROG) was developed and applied for the analysis of tear samples. The method involves a simple extraction procedure of steroids from tears collected on Schirmer strips, followed by a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) analysis. In total, tear samples from 14 DED female patients and 13 healthy female controls were analysed and, CORT, ADIONE, and 17-OHP response levels resulted significantly decreased in dry eye patients respect to controls. The receiver operating characteristic (ROC) curve obtained by the combination of these three steroids (AUC = 0.964) demonstrated the good diagnostic power of the differential tear steroids in identifying DED. In conclusion, the present method made it possible, for the first time, to study steroid profiling directly in tear fluid. Full article

(This article belongs to the Special Issue Dry Eye and Ocular Surface Disorders)

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Open AccessArticle A Simple Defined Medium for the Production of True Diketopiperazines in Xylella fastidiosa and Their Identification by Ultra-Fast Liquid Chromatography-Electrospray Ionization Ion Trap Mass Spectrometry

by Michelli Massaroli da Silva, Moacir dos Santos Andrade, Anelize Bauermeister, Marcus Vinícius Merfa, Moacir Rossi Forim, João Batista Fernandes, Paulo Cezar Vieira, Maria Fátima das Graças Fernandes da Silva, Norberto Peporine Lopes, Marcos Antônio Machado and Alessandra Alves de Souza

Molecules 2017, 22(6), 985; doi:10.3390/molecules22060985

Received: 30 March 2017 / Revised: 24 May 2017 / Accepted: 8 June 2017 / Published: 13 June 2017

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Abstract

Diketopiperazines can be generated by non-enzymatic cyclization of linear dipeptides at extreme temperature or pH, and the complex medium used to culture bacteria and fungi including phytone peptone and trypticase peptone, can also produce cyclic peptides by heat sterilization. As a result, it

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Diketopiperazines can be generated by non-enzymatic cyclization of linear dipeptides at extreme temperature or pH, and the complex medium used to culture bacteria and fungi including phytone peptone and trypticase peptone, can also produce cyclic peptides by heat sterilization. As a result, it is not always clear if many diketopiperazines reported in the literature are artifacts formed by the different complex media used in microorganism growth. An ideal method for analysis of these compounds should identify whether they are either synthesized de novo from the products of primary metabolism and deliver true diketopiperazines. A simple defined medium (X. fastidiosa medium or XFM) containing a single carbon source and no preformed amino acids has emerged as a method with a particularly high potential for the grown of X. fastidiosa and to produce genuine natural products. In this work, we identified a range of diketopiperazines from X. fastidiosa 9a5c growth in XFM, using Ultra-Fast Liquid Chromatography coupled with mass spectrometry. Diketopiperazines are reported for the first time from X. fastidiosa, which is responsible for citrus variegated chlorosis. We also report here fatty acids from X. fastidiosa, which were not biologically active as diffusible signals, and the role of diketopiperazines in signal transduction still remains unknown. Full article

(This article belongs to the Section Natural Products)

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Open AccessArticle Direct Analyses of Secondary Metabolites by Mass Spectrometry Imaging (MSI) from Sunflower (Helianthus annuus L.) Trichomes

by Denise Brentan Silva, Anna-Katharina Aschenbrenner, Norberto Peporine Lopes and Otmar Spring

Molecules 2017, 22(5), 774; doi:10.3390/molecules22050774

Received: 6 April 2017 / Revised: 7 May 2017 / Accepted: 8 May 2017 / Published: 10 May 2017

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Abstract

Helianthus annuus (sunflower) displays non-glandular trichomes (NGT), capitate glandular trichomes (CGT), and linear glandular trichomes (LGT), which reveal different chemical compositions and locations in different plant tissues. With matrix-assisted laser desorption/ionization (MALDI) and laser desorption/ionization (LDI) mass spectrometry imaging (MSI) techniques, efficient methods

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Helianthus annuus (sunflower) displays non-glandular trichomes (NGT), capitate glandular trichomes (CGT), and linear glandular trichomes (LGT), which reveal different chemical compositions and locations in different plant tissues. With matrix-assisted laser desorption/ionization (MALDI) and laser desorption/ionization (LDI) mass spectrometry imaging (MSI) techniques, efficient methods were developed to analyze the tissue distribution of secondary metabolites (flavonoids and sesquiterpenes) and proteins inside of trichomes. Herein, we analyzed sesquiterpene lactones, present in CGT, from leaf transversal sections using the matrix 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (CHCA) (mixture 1:1) with sodium ions added to increase the ionization in positive ion mode. The results observed for sesquiterpenes and polymethoxylated flavones from LGT were similar. However, upon desiccation, LGT changed their shape in the ionization source, complicating analyses by MSI mainly after matrix application. An alternative method could be applied to LGT regions by employing LDI (without matrix) in negative ion mode. The polymethoxylated flavones were easily ionized by LDI, producing images with higher resolution, but the sesquiterpenes were not observed in spectra. Thus, the application and viability of MALDI imaging for the analyses of protein and secondary metabolites inside trichomes were confirmed, highlighting the importance of optimization parameters. Full article

(This article belongs to the Special Issue Special Issue in Honor of Professor Nikolaus (Klaus) Fischer on the Occasion of His 80th Birthday)

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Open AccessArticle A Rapid Magnetic Solid Phase Extraction Method Followed by Liquid Chromatography-Tandem Mass Spectrometry Analysis for the Determination of Mycotoxins in Cereals

by Giorgia La Barbera, Anna Laura Capriotti, Chiara Cavaliere, Patrizia Foglia, Carmela Maria Montone, Riccardo Zenezini Chiozzi and Aldo Laganà

Toxins 2017, 9(4), 147; doi:10.3390/toxins9040147

Received: 28 February 2017 / Revised: 31 March 2017 / Accepted: 19 April 2017 / Published: 21 April 2017

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Abstract

Mycotoxins can contaminate various food commodities, including cereals. Moreover, mycotoxins of different classes can co-contaminate food, increasing human health risk. Several analytical methods have been published in the literature dealing with mycotoxins determination in cereals. Nevertheless, in the present work, the aim was

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Mycotoxins can contaminate various food commodities, including cereals. Moreover, mycotoxins of different classes can co-contaminate food, increasing human health risk. Several analytical methods have been published in the literature dealing with mycotoxins determination in cereals. Nevertheless, in the present work, the aim was to propose an easy and effective system for the extraction of six of the main mycotoxins from corn meal and durum wheat flour, i.e., the main four aflatoxins, ochratoxin A, and the mycoestrogen zearalenone. The developed method exploited magnetic solid phase extraction (SPE), a technique that is attracting an increasing interest as an alternative to classical SPE. Therefore, the use of magnetic graphitized carbon black as a suitable extracting material was tested. The same magnetic material proved to be effective in the extraction of mycoestrogens from milk, but has never been applied to complex matrices as cereals. Ultra high–performance liquid chromatography tandem mass spectrometry was used for detection. Recoveries were >60% in both cereals, even if the matrix effects were not negligible. The limits of quantification of the method results were comparable to those obtained by other two magnetic SPE-based methods applied to cereals, which were limited to one or two mycotoxins, whereas in this work the investigated mycotoxins belonged to three different chemical classes. Full article

(This article belongs to the Section Mycotoxins)

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Open AccessArticle Liquid Chromatography Tandem Mass Spectrometry Analysis of Synthetic Coccidiostats in Eggs

by Francesca Buiarelli, Patrizia Di Filippo, Carmela Riccardi, Donatella Pomata, Luigi Giannetti, Bruno Neri and Daniela Rago

Separations 2017, 4(2), 15; doi:10.3390/separations4020015

Received: 4 January 2017 / Revised: 21 February 2017 / Accepted: 29 March 2017 / Published: 17 April 2017

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Abstract

Coccidiostats are synthetic drugs administered to animals, especially to poultry, to cure coccidiosis. In this paper, we present a selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to analyze residues of five synthetic coccidiostats in eggs: clazuril, diclazuril, robenidine, nicarbazin, toltrazuril and its two

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Coccidiostats are synthetic drugs administered to animals, especially to poultry, to cure coccidiosis. In this paper, we present a selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method to analyze residues of five synthetic coccidiostats in eggs: clazuril, diclazuril, robenidine, nicarbazin, toltrazuril and its two metabolites. The extraction efficiency was evaluated by testing several solvents, pH, different volumes and time of extraction. The clean-up procedures were optimized using different solid phase extraction cartridges and different eluants. The chromatographic separation was achieved in reversed phase using a gradient of 0.1% formic acid in water and acetonitrile, whereas the MS detection was performed in negative electrospray ionization (ESI) for all the analytes, except for the robenidine. The developed method has been validated according to Commission Decision 2002/657/CE. The validation parameters, as linearity, precision, recovery, specificity, decision limit (CCα), detection capability (CCβ), and robustness have been determined. The proposed method resulted simple, fast, and suitable for screening and confirmation purposes. Full article

(This article belongs to the Special Issue Advances in High Pressure Liquid Chromatography)

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Open AccessArticle Oxidation Products of Ester-Based Oils with and without Antioxidants Identified by Stable Isotope Labelling and Mass Spectrometry

by Marcella Frauscher, Charlotte Besser, Günter Allmaier and Nicole Dörr

Appl. Sci. 2017, 7(4), 396; doi:10.3390/app7040396

Received: 2 March 2017 / Revised: 3 April 2017 / Accepted: 10 April 2017 / Published: 16 April 2017

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Abstract

As lubricants with a high thermo-oxidative stability such as synthetic esters are gaining more importance in the lubricant market, a detailed knowledge regarding their oxidative degradation behaviour is of high importance. In order to reveal their degradation products and processes, a novel approach

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As lubricants with a high thermo-oxidative stability such as synthetic esters are gaining more importance in the lubricant market, a detailed knowledge regarding their oxidative degradation behaviour is of high importance. In order to reveal their degradation products and processes, a novel approach combining artificial alteration, isotope labelling based on oxidation with ¹⁶O₂ and ¹⁸O₂, and mass spectrometry (MS), was applied to a bis(2-ethylhexyl) adipate base oil. The degradation products such as 2-ethylhexanol and its monoesters with short-chain fatty acids pinpointed the C–O ester bond as the site prone to oxidative attack, allowing the collection of information about the oxidation mechanisms. Furthermore, the influence of the antioxidant (AO) 4,4′-methylene-bis(2,6-di-tert-butylphenol) as an additive on the oxidation behaviour and resulting products was studied: blends containing AO showed a remarkably higher resistance against oxidation. However, similar degradation products were obtained after AO depletion and without AO. AO cleavage occurred at the carbon atom that bridges the phenols to give 2,6-di-tert-butyl-p-benzoquinone and 3,5-di-tert-butyl-4-hydroxybenzoic acid. By applying the isotope labelling approach, sites of preferential oxidative cleavage and hence differentiation of the origin of oxygen atoms—either from the atmosphere or from base oil components—can be unambiguously related in oxygen-containing base oils, as well as in blends with additives. Full article

(This article belongs to the Special Issue Lubricant Additives)

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Open AccessArticle Analyses of Indole Compounds in Sugar Cane (Saccharum officinarum L.) Juice by High Performance Liquid Chromatography and Liquid Chromatography-Mass Spectrometry after Solid-Phase Extraction

by Jean Wan Hong Yong, Liya Ge, Wei San Wong, Zhen Ma and Swee Ngin Tan

Separations 2017, 4(1), 7; doi:10.3390/separations4010007

Received: 31 December 2016 / Revised: 28 February 2017 / Accepted: 7 March 2017 / Published: 15 March 2017

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Abstract

Simultaneous quantitative analysis of 10 indole compounds, including indole-3-acetic acid (IAA, one of the most important naturally occurring auxins) and some of its metabolites, by high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) after solid-phase extraction (SPE) was reported for the

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Simultaneous quantitative analysis of 10 indole compounds, including indole-3-acetic acid (IAA, one of the most important naturally occurring auxins) and some of its metabolites, by high performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) after solid-phase extraction (SPE) was reported for the first time. The analysis was carried out using a reverse phase HPLC gradient elution, with an aqueous mobile phase (containing 0.1% formic acid) modified by methanol. Furthermore, a novel SPE procedure was developed for the pre-concentration and purification of indole compounds using C₁₈ SPE cartridges. The combination of SPE, HPLC, and LC-MS was applied to screen for the indole compounds present in sugar cane (Saccharum officinarum L.) juice, a refreshing beverage with various health benefits. Finally, four indole compounds were successfully detected and quantified in sugar cane juice by HPLC, which were further unequivocally confirmed by LC-MS/MS experiments operating in the multiple reaction monitoring (MRM) mode. Full article

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Open AccessArticle Tentative Characterization of Polyphenolic Compounds in the Male Flowers of Phoenix dactylifera by Liquid Chromatography Coupled with Mass Spectrometry and DFT

by Ridha Ben Said, Arafa I. Hamed, Usam A. Mahalel, Abdullah Sulaiman Al-Ayed, Mariusz Kowalczyk, Jaroslaw Moldoch, Wieslaw Oleszek and Anna Stochmal

Int. J. Mol. Sci. 2017, 18(3), 512; doi:10.3390/ijms18030512

Received: 28 December 2016 / Revised: 15 February 2017 / Accepted: 20 February 2017 / Published: 2 March 2017

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Abstract

Phoenix dacylifera is an ancient palm species rich in (poly)phenols. These phenolic compounds were tentatively identified by using liquid chromatography coupled with ion spray mass spectrometry in tandem mode (LC/MS/MS) with negative ion detection. Negative identification of the compounds was based on their

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Phoenix dacylifera is an ancient palm species rich in (poly)phenols. These phenolic compounds were tentatively identified by using liquid chromatography coupled with ion spray mass spectrometry in tandem mode (LC/MS/MS) with negative ion detection. Negative identification of the compounds was based on their retention times and mass spectra in full scan mode (MS), and in different MS/MS modes. For the first time, complete hypothesis, and routs for both p-coumaroylshikimic acids (CoSA) and caffeoylshikimic acids (CSA) were suggested and confirmed by Density Fonctional Theory (DFT) study. Notably, of the 53 compounds characterized, 19 hydroxycinnamates derivatives were tentativelycharacterized in male flowers of date palm and 15 of them were recorded for the first time. In addition, five organic acids, six B-type proanthocyanidins, two anthocyanidin and 21 flavonoid derivatives have been tentatively characterized. Identification of B-type proanthocyanidins were based on the diagnostic ions resulting from heterocyclic ring fission (HRF) and retro-Diels-Alder (RDA) reaction of flavan-3-ol provided information on the hydroxylation pattern and the type of inter-flavan bond proanthocyanidins. The sequence of proanthocyanidins was detected through ions extracted from quinone methide (QM) cleavage of the inter-flavan bond. Full article

(This article belongs to the Special Issue Anthocyanins)

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Open AccessArticle Identification of the Geographic Origin of Parmigiano Reggiano (P.D.O.) Cheeses Deploying Non-Targeted Mass Spectrometry and Chemometrics

by Bert Popping, Emiliano De Dominicis, Mario Dante and Marco Nocetti

Foods 2017, 6(2), 13; doi:10.3390/foods6020013

Received: 15 October 2016 / Revised: 12 January 2017 / Accepted: 30 January 2017 / Published: 16 February 2017

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Abstract

Parmigiano Reggiano is an Italian product with a protected designation of origin (P.D.O.). It is an aged hard cheese made from raw milk. P.D.O. products are protected by European regulations. Approximately 3 million wheels are produced each year, and the product attracts a

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Parmigiano Reggiano is an Italian product with a protected designation of origin (P.D.O.). It is an aged hard cheese made from raw milk. P.D.O. products are protected by European regulations. Approximately 3 million wheels are produced each year, and the product attracts a relevant premium price due to its quality and all around the world well known typicity. Due to the high demand that exceeds the production, several fraudulent products can be found on the market. The rate of fraud is estimated between 20% and 40%, the latter predominantly in the grated form. We have developed a non-target method based on Liquid Chomatography-High Resolution Mass Spectrometry (LC-HRMS) that allows the discrimination of Parmigiano Reggiano from non-authentic products with milk from different geographical origins or products, where other aspects of the production process do not comply with the rules laid down in the production specifications for Parmeggiano Reggiano. Based on a database created with authentic samples provided by the Consortium of Parmigiano Reggiano Cheese, a reliable classification model was built. The overall classification capabilities of this non-targeted method was verified on 32 grated cheese samples. The classification was 87.5% accurate. Full article

(This article belongs to the Special Issue Food Identity, Authenticity and Fraud: The Full Spectrum)

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Open AccessArticle Validation and Application of an Ultra High-Performance Liquid Chromatography Tandem Mass Spectrometry Method for Yuanhuacine Determination in Rat Plasma after Pulmonary Administration: Pharmacokinetic Evaluation of a New Drug Delivery System

by Man Li, Xiao Liu, Hao Cai, Zhichun Shen, Liu Xu, Weidong Li, Li Wu, Jinao Duan and Zhipeng Chen

Molecules 2016, 21(12), 1733; doi:10.3390/molecules21121733

Received: 14 November 2016 / Revised: 5 December 2016 / Accepted: 13 December 2016 / Published: 16 December 2016

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Abstract

Yuanhuacine was found to have significant inhibitory activity against A-549 human lung cancer cells. However, there would be serious adverse toxicity effects after systemic administration of yuanhuacine, such as by oral and intravenous ways. In order to achieve better curative effect and to

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Yuanhuacine was found to have significant inhibitory activity against A-549 human lung cancer cells. However, there would be serious adverse toxicity effects after systemic administration of yuanhuacine, such as by oral and intravenous ways. In order to achieve better curative effect and to alleviate the adverse toxicity effects, we tried to deliver yuanhuacine directly into the lungs. Ultra high-performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) was used to detect the analyte and IS. After extraction (ether:dichloromethane = 8:1), the analyte and IS were separated on a Waters BEH-C₁₈ column (100 mm × 2.1 mm, 1.7 μm) under a 5 min gradient elution using a mixture of acetonitrile and 0.1% formic acid aqueous solution as mobile phase at a flow rate of 0.3 mL/min. ESI positive mode was chosen for detection. The method was fully validated for its selectivity, accuracy, precision, stability, matrix effect, and extraction recovery. This new method for yuanhuacine concentration determination in rat plasma was reliable and could be applied for its preclinical and clinical monitoring purpose. Full article

(This article belongs to the Section Medicinal Chemistry)

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Open AccessArticle Harmonized Collaborative Validation of Aflatoxins and Sterigmatocystin in White Rice and Sorghum by Liquid Chromatography Coupled to Tandem Mass Spectrometry

by Hyun Ee Ok, Fei Tian, Eun Young Hong, Ockjin Paek, Sheen-Hee Kim, Dongsul Kim and Hyang Sook Chun

Toxins 2016, 8(12), 371; doi:10.3390/toxins8120371

Received: 5 October 2016 / Revised: 5 December 2016 / Accepted: 6 December 2016 / Published: 13 December 2016

Abstract

An interlaboratory study was performed in eight laboratories to validate a liquid chromatography–tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of aflatoxins and sterigmatocystin (STC) in white rice and sorghum (Sorghum bicolor). Fortified samples (at three different levels) of white

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An interlaboratory study was performed in eight laboratories to validate a liquid chromatography–tandem mass spectrometry (LC/MS/MS) method for the simultaneous determination of aflatoxins and sterigmatocystin (STC) in white rice and sorghum (Sorghum bicolor). Fortified samples (at three different levels) of white rice and sorghum were extracted, purified through a solid-phase extraction (SPE) column, and then analyzed by LC/MS/MS. The apparent recoveries (ARs) ranged from 78.8% to 95.0% for aflatoxins and from 85.3% to 96.7% for STC. The relative standard deviations for repeatability (RSD_r) and reproducibility (RSDR) of aflatoxins were in the ranges 7.9%–33.8% and 24.4%–81.0%, respectively. For STC, the RSD_r ranged from 7.1% to 40.2% and the RSDR ranged from 28.1% to 99.2%. The Horwitz ratio values for the aflatoxins and STC ranged from 0.4 to 1.2 in white rice and from 0.3 to 1.0 in sorghum, respectively. These results validated this method for the simultaneous determination of aflatoxins and STC by LC/MS/MS after SPE column cleanup. The percentages of satisfactory Z-score values (|Z| ≤ 2) were the following: for white rice, 100% for aflatoxins and STC; for sorghum, 100%, except in data from two laboratories for STC (0.3 μg/kg). This validated that the LC/MS/MS method was successfully applied for the determination of aflatoxins and STC in 20 white rice and 20 sorghum samples sourced from Korean markets. Full article

(This article belongs to the Special Issue LC-MS/MS Method for Mycotoxin Analysis)

Open AccessArticle Using Light Microscopy and Liquid Chromatography Tandem Mass Spectrometry for Qualitative and Quantitative Control of a Combined Three-Herb Formulation in Different Preparations

by Tun-Pin Hsueh, Wan-Ling Lin and Tung-Hu Tsai

Molecules 2016, 21(12), 1673; doi:10.3390/molecules21121673

Received: 10 November 2016 / Revised: 1 December 2016 / Accepted: 1 December 2016 / Published: 6 December 2016

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Abstract

Artemisia capillaries Thunb, Gardenia jasminoides Ellis, and Rheum officinale Baill have been combined to treat jaundice for thousands of years. Studies have revealed that these herbs induce anti-hepatic fibrosis and anti-hepatic apoptosis and alleviate hepatic oxidative stress. This study aims to determine the

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Artemisia capillaries Thunb, Gardenia jasminoides Ellis, and Rheum officinale Baill have been combined to treat jaundice for thousands of years. Studies have revealed that these herbs induce anti-hepatic fibrosis and anti-hepatic apoptosis and alleviate hepatic oxidative stress. This study aims to determine the quality and quantity of an herbal formulation (Chinese name: Yin-Chen-Hao-Tang) using physical and chemical examinations. Physical examination of Yin-Chen-Hao-Tang in pharmaceutical herbal products, raw fiber powders, and decoction preparations was performed using Congo red and iodine-potassium staining. A sensitive and validated method employing ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) was developed to simultaneously quantify the bioactive compounds scoparone, geniposide, and rhein in the Yin-Chen-Hao-Tang formulation in different preparations. Physical examination indicated that cellulose fibers with irregular round shapes were present in the pharmaceutical herbal products. The developed UHPLC-MS/MS method showed good linearity and was well validated. The quantification results revealed that the decoction preparations had the highest amounts of geniposide and rhein. Scoparone appeared in pharmaceutical herbal products from two manufacturers. This experiment provides a qualitative and quantitative method using physical and chemical examinations to test different preparations of herbal products. The results provide a reference for clinical herbal product preparations and further pharmacokinetic research. Full article

(This article belongs to the collection Herbal Medicine Research)

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Open AccessTechnical Note A Non-Derivatized Assay for the Simultaneous Detection of Amino Acids, Acylcarnitines, Succinylacetone, Creatine, and Guanidinoacetic Acid in Dried Blood Spots via Tandem Mass Spectrometry

by Carter K. Asef, Kameron M. Khaksarfard and Víctor R. De Jesús

Int. J. Neonatal Screen. 2016, 2(4), 13; doi:10.3390/ijns2040013

Received: 30 August 2016 / Revised: 9 November 2016 / Accepted: 17 November 2016 / Published: 24 November 2016

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Abstract

Guanidinoacetate methyltransferase (GAMT) deficiency is an autosomal recessive genetic disorder which results in global developmental delay and intellectual disability. There is evidence that early treatment prevents intellectual disability and seizures. GAMT deficiency is now being discussed as a potential addition to the U.S.

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Guanidinoacetate methyltransferase (GAMT) deficiency is an autosomal recessive genetic disorder which results in global developmental delay and intellectual disability. There is evidence that early treatment prevents intellectual disability and seizures. GAMT deficiency is now being discussed as a potential addition to the U.S. Recommended Uniform Screening Panel (RUSP); the availability of suitable screening methods must be considered. A neonatal screening derivatized method to quantify creatine (CRE) and guanidinoacetic acid (GAA) in dried blood spots by tandem mass spectrometry (MS/MS) has been described. Its key feature is the ability to detect CRE and GAA in the same extract generated from neonatal dried blood spots (DBS’s) during amino acids (AA) and acylcarnitines (AC) analysis. More laboratories are adopting non-derivatized MS/MS screening methods. We describe an improved, non-derivatized DBS extraction and MS/MS analytical method (AAAC-GAMT) that incorporates quantitation of CRE and GAA into routine analysis of amino acids, acylcarnitines, and succinylacetone. The non-derivatized AAAC-GAMT method performs comparably to the stand-alone GAMT and non-derivatized AAAC screening methods, supporting its potential suitability for high-throughput GAMT neonatal screening. Full article

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Open AccessCommunication Direct Separation of Pregabalin Enantiomers Using a Zwitterionic Chiral Selector by High Performance Liquid Chromatography Coupled to Mass Spectrometry and Ultraviolet Detection

by Lakshmi Narayana Chennuru, Thirupathi Choppari, Ramakrishna Prasad Nandula, Tong Zhang and Pilar Franco

Molecules 2016, 21(11), 1578; doi:10.3390/molecules21111578

Received: 31 October 2016 / Revised: 14 November 2016 / Accepted: 15 November 2016 / Published: 19 November 2016

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Abstract

The chromatographic resolution of pregabalin enantiomers has been often achieved by derivatization of the molecule, in order to reach enough sensitivity at low concentrations of the minor enantiomer present in the active principle. In the present article, the development and optimization of two

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The chromatographic resolution of pregabalin enantiomers has been often achieved by derivatization of the molecule, in order to reach enough sensitivity at low concentrations of the minor enantiomer present in the active principle. In the present article, the development and optimization of two liquid chromatographic methods are presented for the direct resolution of pregabalin enantiomers on a chiral stationary phase (CSP) containing a zwitterionic selector derived from cinchona alkaloid and sulfonic acid (CHIRALPAK ZWIX). The key parameters for the separation as well as the compatibility of chromatographic conditions with different detection modes (ultraviolet and mass spectrometry) were investigated. The resulting methods were found to be selective, of high performance and low limits of detection (2 µg/mL by UV and 1 ng/mL by MS, respectively) and quantification (6 µg/mL by UV and 5 ng/mL by MS, respectively) for the minor enantiomer which is considered as a chiral impurity. Full article

(This article belongs to the Special Issue Chromatographic Separation of Enantiomers: Commemorative Issue in Honor of Professor Stig Allenmark on the Occasion of His 80th Birthday)

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Open AccessArticle Simultaneous Determination of Coumarin and Its Derivatives in Tobacco Products by Liquid Chromatography-Tandem Mass Spectrometry

by Zhiqin Ren, Bo Nie, Tong Liu, Fei Yuan, Feng Feng, Yuan Zhang, Weie Zhou, Xiuli Xu, Meiyi Yao and Feng Zhang

Molecules 2016, 21(11), 1511; doi:10.3390/molecules21111511

Received: 21 July 2016 / Revised: 30 October 2016 / Accepted: 1 November 2016 / Published: 10 November 2016

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Abstract

In this paper an analytical method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the determination of coumarin and its derivatives in tobacco products was developed. The MS/MS fragmentation pathways of the eight coumarins were elucidated. The new

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In this paper an analytical method based on high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) for the determination of coumarin and its derivatives in tobacco products was developed. The MS/MS fragmentation pathways of the eight coumarins were elucidated. The new analytical method was defined based on two main axes, an extraction procedure with acetonitrile and analyte detection performed by HPLC-MS/MS in electron impact mode. The excellent selectivity and sensitivity achieved in multiple reaction monitoring (MRM) mode allowed satisfactory confirmation and quantitation for the coumarin flavor additives. Under the optimized gradient elution conditions, it took only 4.5 min to separate all eight coumarins. Good linearity for all the analytes were confirmed by the correlation coefficient r², ranging from 0.9987 to 0.9996. The limits of detection (LODs) and limits of quantitation (LOQs) of these compounds were in the range of 0.5–1.7 μg/kg and 1.7–5.2 μg/kg, respectively. The average recoveries at three spiked levels (LOQ, 1.5LOQ, 2LOQ) were all in the range of 69.6%–95.1% with RSDs (n = 6) lower than 5.3%. The method of HPLC-MS/MS developed in this study was initially applied to the research of coumarin flavor additives in tobacco products collected from the located market in Beijing from China and proved to be accurate, sensitive, convenient and practical. Full article

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Open AccessArticle A Proof of Concept to Bridge the Gap between Mass Spectrometry Imaging, Protein Identification and Relative Quantitation: MSI~LC-MS/MS-LF

by Laëtitia Théron, Delphine Centeno, Cécile Coudy-Gandilhon, Estelle Pujos-Guillot, Thierry Astruc, Didier Rémond, Jean-Claude Barthelemy, Frédéric Roche, Léonard Feasson, Michel Hébraud, Daniel Béchet and Christophe Chambon

Proteomes 2016, 4(4), 32; doi:10.3390/proteomes4040032

Received: 15 July 2016 / Revised: 4 October 2016 / Accepted: 17 October 2016 / Published: 26 October 2016

Abstract

Mass spectrometry imaging (MSI) is a powerful tool to visualize the spatial distribution of molecules on a tissue section. The main limitation of MALDI-MSI of proteins is the lack of direct identification. Therefore, this study focuses on a MSI~LC-MS/MS-LF workflow to link the

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Mass spectrometry imaging (MSI) is a powerful tool to visualize the spatial distribution of molecules on a tissue section. The main limitation of MALDI-MSI of proteins is the lack of direct identification. Therefore, this study focuses on a MSI~LC-MS/MS-LF workflow to link the results from MALDI-MSI with potential peak identification and label-free quantitation, using only one tissue section. At first, we studied the impact of matrix deposition and laser ablation on protein extraction from the tissue section. Then, we did a back-correlation of the m/z of the proteins detected by MALDI-MSI to those identified by label-free quantitation. This allowed us to compare the label-free quantitation of proteins obtained in LC-MS/MS with the peak intensities observed in MALDI-MSI. We managed to link identification to nine peaks observed by MALDI-MSI. The results showed that the MSI~LC-MS/MS-LF workflow (i) allowed us to study a representative muscle proteome compared to a classical bottom-up workflow; and (ii) was sparsely impacted by matrix deposition and laser ablation. This workflow, performed as a proof-of-concept, suggests that a single tissue section can be used to perform MALDI-MSI and protein extraction, identification, and relative quantitation. Full article

(This article belongs to the Special Issue Computational Proteomics)

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Open AccessReview Trace Element Analysis of Minerals in Magmatic-Hydrothermal Ores by Laser Ablation Inductively-Coupled Plasma Mass Spectrometry: Approaches and Opportunities

by Nigel Cook, Cristiana L. Ciobanu, Luke George, Zhi-Yong Zhu, Benjamin Wade and Kathy Ehrig

Minerals 2016, 6(4), 111; doi:10.3390/min6040111

Received: 31 July 2016 / Revised: 15 August 2016 / Accepted: 16 August 2016 / Published: 20 October 2016

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Abstract

Laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) has rapidly established itself as the method of choice for generation of multi-element datasets for specific minerals, with broad applications in Earth science. Variation in absolute concentrations of different trace elements within common, widely distributed phases,

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Laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) has rapidly established itself as the method of choice for generation of multi-element datasets for specific minerals, with broad applications in Earth science. Variation in absolute concentrations of different trace elements within common, widely distributed phases, such as pyrite, iron-oxides (magnetite and hematite), and key accessory minerals, such as apatite and titanite, can be particularly valuable for understanding processes of ore formation, and when trace element distributions vary systematically within a mineral system, for a vector approach in mineral exploration. LA-ICP-MS trace element data can assist in element deportment and geometallurgical studies, providing proof of which minerals host key elements of economic relevance, or elements that are deleterious to various metallurgical processes. This contribution reviews recent advances in LA-ICP-MS methodology, reference standards, the application of the method to new mineral matrices, outstanding analytical uncertainties that impact on the quality and usefulness of trace element data, and future applications of the technique. We illustrate how data interpretation is highly dependent on an adequate understanding of prevailing mineral textures, geological history, and in some cases, crystal structure. Full article

(This article belongs to the Special Issue Advances in Mineral Analytical Techniques)

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Open AccessArticle Development and Validation of Miglitol and Its Impurities by RP-HPLC and Characterization Using Mass Spectrometry Techniques

by Kesavan Balakumaran, Mosesbabu Janagili, Nagaraju Rajana, Sureshbabu Papureddy and Jayashree Anireddy

Sci. Pharm. 2016, 84(4), 654-670; doi:10.3390/scipharm84040654

Received: 23 April 2016 / Accepted: 11 August 2016 / Published: 14 October 2016

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Abstract

Alpha glucoside inhibitors used to treat type-2 diabetes mellitus (DM) are likely to be safe and effective. These agents are most effective for postprandial hyperglycemia. Miglitol is a type of drug used to treat type-2 DM. A simple, selective, linear, precise and accurate

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Alpha glucoside inhibitors used to treat type-2 diabetes mellitus (DM) are likely to be safe and effective. These agents are most effective for postprandial hyperglycemia. Miglitol is a type of drug used to treat type-2 DM. A simple, selective, linear, precise and accurate reversed-phase high-performance liquid chromatography (RP-HPLC) method was developed and validated for a related substance of miglitol and its identification, and characterization was done by different mass spectrometry techniques. The gradient method at a flow rate of 1.0 mL/min was employed on a prevail carbohydrate ES column (250 × 4.6 mm, 5 μm particle size) at a temperature of 35 °C. Mobile phase A consisted of 10 mM dipotassium hydrogen orthophosphate adjusted to pH 8.0 using concentrated phosphoric acid and mobile phase B consisted of acetonitrile. The ultraviolet detection wavelength was 210 nm and 20 μL of the sample were injected. The retention time for miglitol was about 24.0 min. Forced degradation of the miglitol sample was conducted in accordance with the International Conference on Harmonisation (ICH) guidelines. Acidic, basic, neutral, and oxidative hydrolysis, thermal stress, and photolytic degradation were used to assess the stability-indicating the power of the method. Substantial degradation was observed during oxidative hydrolysis. No degradation was observed under the other stress conditions. The method was optimized using samples generated by forced degradation and sample solutions spiked with impurities and epimers. Good resolution of the analyte peak from peaks, corresponding to process-related impurities, epimers and degradation products, was achieved and the method was validated as per the ICH guidelines. The method can successfully be applied for routine analysis of miglitol. Full article

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Open AccessArticle The Profiling and Identification of the Absorbed Constituents and Metabolites of Guizhi Decoction in Rat Plasma and Urine by Rapid Resolution Liquid Chromatography Combined with Quadrupole-Time-of-Flight Mass Spectrometry

by Hongjun Xiang, Lishi Zhang, Jiannan Song, Bin Fan, Yinglan Nie, Dong Bai and Haimin Lei

Int. J. Mol. Sci. 2016, 17(9), 1409; doi:10.3390/ijms17091409

Received: 20 June 2016 / Revised: 21 July 2016 / Accepted: 12 August 2016 / Published: 12 September 2016

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Abstract

Guizhi decoction (GZD), a well-known traditional Chinese medicine (TCM) prescription consisting of Ramulus Cinnamomi, Radix Paeoniae Alba, Radix Glycyrrhizae, Fructus Jujubae and Rhizoma Zingiberis Recens, is usually used for the treatment of common colds, influenza, and other pyretic conditions in the clinic. However,

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Guizhi decoction (GZD), a well-known traditional Chinese medicine (TCM) prescription consisting of Ramulus Cinnamomi, Radix Paeoniae Alba, Radix Glycyrrhizae, Fructus Jujubae and Rhizoma Zingiberis Recens, is usually used for the treatment of common colds, influenza, and other pyretic conditions in the clinic. However, the absorbed ingredients and metabolic compounds of GZD have not been reported. In this paper, a method incorporating rapid resolution liquid chromatography (RRLC) with quadrupole-time-of-flight mass spectrometry (Q-TOF-MS) was used to identify ingredients after oral administration of GZD. Identification of the primary components in GZD, drug-containing serum and urine samples was carried out in order to investigate the assimilation and metabolites of the decoction in vivo. By comparing the total ion chromatograms (TICs) of GZD, a total of 71 constituents were detected or characterized. By comparing TICs of blank and dosed rat plasma, a total of 15 constituents were detected and identified as prototypes according to their retention time (t_R) and MS, MS/MS data. Based on this, neutral loss scans of 80 and 176 Da in samples of rat plasma and urine helped us to identify most of the metabolites. Results showed that the predominant metabolic pathways of (epi) catechin and gallic acid were sulfation, methylation, glucuronidation and dehydroxylation; the major metabolic pathways of flavone were hydrolysis, sulfation and glucuronidation. Furthermore, degradation, oxidation and ring fission were found to often occur in the metabolism process of GZD in vivo. Full article

(This article belongs to the Section Bioactives and Nutraceuticals)

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Open AccessArticle Analysis of Sheng-Mai-San, a Ginseng-Containing Multiple Components Traditional Chinese Herbal Medicine Using Liquid Chromatography Tandem Mass Spectrometry and Physical Examination by Electron and Light Microscopies

by Yung-Yi Cheng and Tung-Hu Tsai

Molecules 2016, 21(9), 1159; doi:10.3390/molecules21091159

Received: 15 June 2016 / Revised: 15 August 2016 / Accepted: 25 August 2016 / Published: 1 September 2016

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Abstract

Sheng-Mai-San is a multi-component traditional Chinese herbal preparation. Due to the fact granulated additives, such as starch, carboxymethyl cellulose, lactose and raw herbal powder may alter the content of the bioactive markers in the herbal products, a developed ultra-high performance liquid chromatography tandem

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Sheng-Mai-San is a multi-component traditional Chinese herbal preparation. Due to the fact granulated additives, such as starch, carboxymethyl cellulose, lactose and raw herbal powder may alter the content of the bioactive markers in the herbal products, a developed ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was used to measure the herbal biomarkers of ginsenoside Rb₁, Rb₂, Rc, Rd, Re, Rg₁, Rh₁, compound K, ophiopogonin D and schizandrin from the Sheng-Mai-San herbal formulation. Besides, scanning electron microscopy (SEM) was used to observe the morphology of the herbal granular powders. Light microscopy with Congo red and iodine-KI reagent staining was used to identify the cellulose fiber and cornstarch added to pharmaceutical herbal products. The swelling power (SP), water solubility index (WSI), and crude fiber analysis were used to determine the contents of cellulose fiber and cornstarch in pharmaceutical herbal products. In this study, we developed a novel skill to assess the quantification of appended cornstarch in pharmaceutical herbal products using Aperio ImageScope software. Compared with the traditional cornstarch analysis, our analysis method is a rapid, simple and conversion process which could be applied to detect the percentage of added cornstarch in unknown powder products. The various range of the herbal content for the five pharmaceutical manufacturers varied by up to several hundreds-fold. The physical examination reveals that the morphology of the herbal pharmaceutical products is rough and irregular with sharp layers. This study provides a reference standard operating procedure guide for the quality control of the Chinese herbal pharmaceutical products of Sheng-Mai-San. Full article

(This article belongs to the Section Natural Products)

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Open AccessReview Selecting Sample Preparation Workflows for Mass Spectrometry-Based Proteomic and Phosphoproteomic Analysis of Patient Samples with Acute Myeloid Leukemia

by Maria Hernandez-Valladares, Elise Aasebø, Frode Selheim, Frode S. Berven and Øystein Bruserud

Proteomes 2016, 4(3), 24; doi:10.3390/proteomes4030024

Received: 6 July 2016 / Revised: 9 August 2016 / Accepted: 12 August 2016 / Published: 22 August 2016

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Abstract

Global mass spectrometry (MS)-based proteomic and phosphoproteomic studies of acute myeloid leukemia (AML) biomarkers represent a powerful strategy to identify and confirm proteins and their phosphorylated modifications that could be applied in diagnosis and prognosis, as a support for individual treatment regimens and

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Global mass spectrometry (MS)-based proteomic and phosphoproteomic studies of acute myeloid leukemia (AML) biomarkers represent a powerful strategy to identify and confirm proteins and their phosphorylated modifications that could be applied in diagnosis and prognosis, as a support for individual treatment regimens and selection of patients for bone marrow transplant. MS-based studies require optimal and reproducible workflows that allow a satisfactory coverage of the proteome and its modifications. Preparation of samples for global MS analysis is a crucial step and it usually requires method testing, tuning and optimization. Different proteomic workflows that have been used to prepare AML patient samples for global MS analysis usually include a standard protein in-solution digestion procedure with a urea-based lysis buffer. The enrichment of phosphopeptides from AML patient samples has previously been carried out either with immobilized metal affinity chromatography (IMAC) or metal oxide affinity chromatography (MOAC). We have recently tested several methods of sample preparation for MS analysis of the AML proteome and phosphoproteome and introduced filter-aided sample preparation (FASP) as a superior methodology for the sensitive and reproducible generation of peptides from patient samples. FASP-prepared peptides can be further fractionated or IMAC-enriched for proteome or phosphoproteome analyses. Herein, we will review both in-solution and FASP-based sample preparation workflows and encourage the use of the latter for the highest protein and phosphorylation coverage and reproducibility. Full article

(This article belongs to the Special Issue Clinical Proteomics)

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Open AccessArticle Monoacylglycerol Analysis Using MS/MS^ALL Quadruple Time of Flight Mass Spectrometry

by Fei Gao, Justice McDaniel, Emily Y. Chen, Hannah Rockwell, Matthew D. Lynes, Yu-Hua Tseng, Rangaprasad Sarangarajan, Niven R. Narain and Michael A. Kiebish

Metabolites 2016, 6(3), 25; doi:10.3390/metabo6030025

Received: 16 June 2016 / Revised: 9 August 2016 / Accepted: 12 August 2016 / Published: 17 August 2016

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Abstract

Monoacylglycerols (MAGs) are structural and bioactive metabolites critical for biological function. Development of facile tools for measuring MAG are essential to understand its role in different diseases and various pathways. A data-independent acquisition method, MS/MS^ALL, using electrospray ionization (ESI) coupled quadrupole

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Monoacylglycerols (MAGs) are structural and bioactive metabolites critical for biological function. Development of facile tools for measuring MAG are essential to understand its role in different diseases and various pathways. A data-independent acquisition method, MS/MS^ALL, using electrospray ionization (ESI) coupled quadrupole time of flight mass spectrometry (MS), was utilized for the structural identification and quantitative analysis of individual MAG molecular species. Compared with other acylglycerols, diacylglycerols (DAG) and triacylglycerols (TAG), MAG characteristically presented as a dominant protonated ion, [M + H]⁺, and under low collision energy as fatty acid-like fragments due to the neutral loss of the glycerol head group. At low concentrations (<10 pmol/µL), where lipid-lipid interactions are rare, there was a strong linear correlation between ion abundance and MAG concentration. Moreover, using the MS/MS^ALL method the major MAG species from human plasma and mouse brown and white adipose tissues were quantified in less than 6 min. Collectively, these results demonstrate that MS/MS^ALL analysis of MAG is an enabling strategy for the direct identification and quantitative analysis of low level MAG species from biological samples with high throughput and sensitivity. Full article

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Open AccessArticle MALDI Mass Spectrometry Imaging Reveals Decreased CK5 Levels in Vulvar Squamous Cell Carcinomas Compared to the Precursor Lesion Differentiated Vulvar Intraepithelial Neoplasia

by Chao Zhang, Georgia Arentz, Lyron Winderbaum, Noor A. Lokman, Manuela Klingler-Hoffmann, Parul Mittal, Christopher Carter, Martin K. Oehler and Peter Hoffmann

Int. J. Mol. Sci. 2016, 17(7), 1088; doi:10.3390/ijms17071088

Received: 10 May 2016 / Revised: 24 June 2016 / Accepted: 30 June 2016 / Published: 8 July 2016

Abstract

Vulvar cancer is the fourth most common gynecological cancer worldwide. However, limited studies have been completed on the molecular characterization of vulvar squamous cell carcinoma resulting in a poor understanding of the disease initiation and progression. Analysis and early detection of the precursor

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Vulvar cancer is the fourth most common gynecological cancer worldwide. However, limited studies have been completed on the molecular characterization of vulvar squamous cell carcinoma resulting in a poor understanding of the disease initiation and progression. Analysis and early detection of the precursor lesion of HPV-independent vulvar squamous cell carcinoma (VSCC), differentiated vulvar intraepithelial neoplasia (dVIN), is of great importance given dVIN lesions have a high level of malignant potential. Here we present an examination of adjacent normal vulvar epithelium, dVIN, and VSCC from six patients by peptide Matrix-assisted laser desorption/ionization Mass Spectrometry Imaging (MALDI-MSI). The results reveal the differential expression of multiple peptides from the protein cytokeratin 5 (CK5) across the three vulvar tissue types. The difference observed in the relative abundance of CK5 by MALDI-MSI between the healthy epithelium, dVIN, and VSCC was further analyzed by immunohistochemistry (IHC) in tissue from eight VSCC patients. A decrease in CK5 immunostaining was observed in the VSCC compared to the healthy epithelium and dVIN. These results provide an insight into the molecular fingerprint of the vulvar intraepithelial neoplasia that appears to be more closely related to the healthy epithelium than the VSCC. Full article

(This article belongs to the Special Issue Cancer Molecular Imaging in the Era of Precision Medicine)

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Open AccessArticle Protonation Sites, Tandem Mass Spectrometry and Computational Calculations of o-Carbonyl Carbazolequinone Derivatives

by Maximiliano Martínez-Cifuentes, Graciela Clavijo-Allancan, Pamela Zuñiga-Hormazabal, Braulio Aranda, Andrés Barriga, Boris Weiss-López and Ramiro Araya-Maturana

Int. J. Mol. Sci. 2016, 17(7), 1071; doi:10.3390/ijms17071071

Received: 3 May 2016 / Revised: 10 June 2016 / Accepted: 28 June 2016 / Published: 5 July 2016

Abstract

A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical

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A series of a new type of tetracyclic carbazolequinones incorporating a carbonyl group at the ortho position relative to the quinone moiety was synthesized and analyzed by tandem electrospray ionization mass spectrometry (ESI/MS-MS), using Collision-Induced Dissociation (CID) to dissociate the protonated species. Theoretical parameters such as molecular electrostatic potential (MEP), local Fukui functions and local Parr function for electrophilic attack as well as proton affinity (PA) and gas phase basicity (GB), were used to explain the preferred protonation sites. Transition states of some main fragmentation routes were obtained and the energies calculated at density functional theory (DFT) B3LYP level were compared with the obtained by ab initio quadratic configuration interaction with single and double excitation (QCISD). The results are in accordance with the observed distribution of ions. The nature of the substituents in the aromatic ring has a notable impact on the fragmentation routes of the molecules. Full article

(This article belongs to the Special Issue Chemical Bond and Bonding 2016)

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Open AccessArticle Development and Validation of an Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry Method for Simultaneous Determination of Four Type B Trichothecenes and Masked Deoxynivalenol in Various Feed Products

by Zhichen Fan, Bing Bai, Peng Jin, Kai Fan, Wenbo Guo, Zhihui Zhao and Zheng Han

Molecules 2016, 21(6), 747; doi:10.3390/molecules21060747

Received: 9 March 2016 / Revised: 21 May 2016 / Accepted: 30 May 2016 / Published: 8 June 2016

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Abstract

A reliable and sensitive analytical method was developed for simultaneous determination of deoxynivalenol(DON), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), fusarenon X (FUS-X), and masked deoxynivalenol (deoxynivalenol-3-glucoside, D3G) in formula feed, concentrated feed, and premixed feed products. The method was based on an improved sample pretreatment

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A reliable and sensitive analytical method was developed for simultaneous determination of deoxynivalenol(DON), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), fusarenon X (FUS-X), and masked deoxynivalenol (deoxynivalenol-3-glucoside, D3G) in formula feed, concentrated feed, and premixed feed products. The method was based on an improved sample pretreatment with the commercially available HLB cartridges used for sample purification and enrichment followed by analysis using ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Several key parameters including the extraction solvents, the positions of sample loading solvents, washing and elution solvents for HLB cartridges were carefully optimized to achieve optimal extraction and purification efficiencies. The established method was extensively validated by determining the linearity (R² ≥ 0.99), sensitivity (limit of quantification in the range of 0.08–4.85 μg/kg), recovery (79.3%–108.1%), precision (Intra-day RSDs ≤ 13.5% and Inter-day RSDs ≤ 14.9%), and then was successfully applied to determine the four type B trichothecenes and D3G in a total of 31 feed samples. Among them, 26 were contaminated with various mycotoxins at the levels of 2.1–864.5 μg/kg, and D3G has also been detected in 17 samples with the concentrations in the range of 2.1–34.8 μg/kg, proving the established method to be a valuable tool for type B trichothecenes and masked DON monitoring in complex feed matrices. Full article

(This article belongs to the Section Natural Products)

Open AccessArticle High-Performance Liquid Chromatography with Diode Array Detector and Electrospray Ionization Ion Trap Time-of-Flight Tandem Mass Spectrometry to Evaluate Ginseng Roots and Rhizomes from Different Regions

by Hong-Ping Wang, You-Bo Zhang, Xiu-Wei Yang, Xin-Bao Yang, Wei Xu, Feng Xu, Shao-Qing Cai, Ying-Ping Wang, Yong-Hua Xu and Lian-Xue Zhang

Molecules 2016, 21(5), 603; doi:10.3390/molecules21050603

Received: 27 February 2016 / Revised: 30 April 2016 / Accepted: 5 May 2016 / Published: 9 May 2016

Abstract

Ginseng, Panax ginseng C. A. Meyer, is an industrial crop in China and Korea. The functional components in ginseng roots and rhizomes are characteristic ginsenosides. This work developed a new high-performance liquid chromatography coupled with electrospray ionization ion trap time-of-flight multistage mass spectrometry

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Ginseng, Panax ginseng C. A. Meyer, is an industrial crop in China and Korea. The functional components in ginseng roots and rhizomes are characteristic ginsenosides. This work developed a new high-performance liquid chromatography coupled with electrospray ionization ion trap time-of-flight multistage mass spectrometry (LC–ESI-IT-TOF-MSⁿ) method to identify the triterpenoids. Sixty compounds (1–60) including 58 triterpenoids were identified from the ginseng cultivated in China. Substances 1, 2, 7, 15–20, 35, 39, 45–47, 49, 55–57, 59, and 60 were identified for the first time. To evaluate the quality of ginseng cultivated in Northeast China, this paper developed a practical liquid chromatography–diode array detection (LC–DAD) method to simultaneously quantify 14 interesting ginsenosides in ginseng collected from 66 different producing areas for the first time. The results showed the quality of ginseng roots and rhizomes from different sources was different due to growing environment, cultivation technology, and so on. The developed LC–ESI-IT-TOF-MSⁿ method can be used to identify many more ginsenosides and the LC–DAD method can be used not only to assess the quality of ginseng, but also to optimize the cultivation conditions for the production of ginsenosides. Full article

(This article belongs to the Special Issue Triterpenes and Triterpenoids 2016)

Open AccessReview Advantages and Pitfalls of Mass Spectrometry Based Metabolome Profiling in Systems Biology

by Ina Aretz and David Meierhofer

Int. J. Mol. Sci. 2016, 17(5), 632; doi:10.3390/ijms17050632

Received: 22 March 2016 / Revised: 19 April 2016 / Accepted: 21 April 2016 / Published: 27 April 2016

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Abstract

Mass spectrometry-based metabolome profiling became the method of choice in systems biology approaches and aims to enhance biological understanding of complex biological systems. Genomics, transcriptomics, and proteomics are well established technologies and are commonly used by many scientists. In comparison, metabolomics is an

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Mass spectrometry-based metabolome profiling became the method of choice in systems biology approaches and aims to enhance biological understanding of complex biological systems. Genomics, transcriptomics, and proteomics are well established technologies and are commonly used by many scientists. In comparison, metabolomics is an emerging field and has not reached such high-throughput, routine and coverage than other omics technologies. Nevertheless, substantial improvements were achieved during the last years. Integrated data derived from multi-omics approaches will provide a deeper understanding of entire biological systems. Metabolome profiling is mainly hampered by its diversity, variation of metabolite concentration by several orders of magnitude and biological data interpretation. Thus, multiple approaches are required to cover most of the metabolites. No software tool is capable of comprehensively translating all the data into a biologically meaningful context yet. In this review, we discuss the advantages of metabolome profiling and main obstacles limiting progress in systems biology. Full article

(This article belongs to the Special Issue Metabolomic Technologies in Medicine)

Open AccessArticle Mechanical Modulation of Phonon-Assisted Field Emission in a Silicon Nanomembrane Detector for Time-of-Flight Mass Spectrometry

by Jonghoo Park and Robert H. Blick

Sensors 2016, 16(2), 200; doi:10.3390/s16020200

Received: 18 November 2015 / Revised: 27 January 2016 / Accepted: 2 February 2016 / Published: 5 February 2016

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Abstract

We demonstrate mechanical modulation of phonon-assisted field emission in a free-standing silicon nanomembrane detector for time-of-flight mass spectrometry of proteins. The impacts of ion bombardment on the silicon nanomembrane have been explored in both mechanical and electrical points of view. Locally elevated lattice

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We demonstrate mechanical modulation of phonon-assisted field emission in a free-standing silicon nanomembrane detector for time-of-flight mass spectrometry of proteins. The impacts of ion bombardment on the silicon nanomembrane have been explored in both mechanical and electrical points of view. Locally elevated lattice temperature in the silicon nanomembrane, resulting from the transduction of ion kinetic energy into thermal energy through the ion bombardment, induces not only phonon-assisted field emission but also a mechanical vibration in the silicon nanomembrane. The coupling of these mechanical and electrical phenomenon leads to mechanical modulation of phonon-assisted field emission. The thermal energy relaxation through mechanical vibration in addition to the lateral heat conduction and field emission in the silicon nanomembrane offers effective cooling of the nanomembrane, thereby allowing high resolution mass analysis. Full article

(This article belongs to the Section Biosensors)

Open AccessArticle Liquid Chromatography-Mass Spectrometry-Based Rapid Secondary-Metabolite Profiling of Marine Pseudoalteromonas sp. M2

by Woo Jung Kim, Young Ok Kim, Jin Hee Kim, Bo-Hye Nam, Dong-Gyun Kim, Cheul Min An, Jun Sik Lee, Pan Soo Kim, Hye Min Lee, Joa-Sup Oh and Jong Suk Lee

Mar. Drugs 2016, 14(1), 24; doi:10.3390/md14010024

Received: 14 October 2015 / Revised: 5 January 2016 / Accepted: 11 January 2016 / Published: 20 January 2016

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Abstract

The ocean is a rich resource of flora, fauna, and food. A wild-type bacterial strain showing confluent growth on marine agar with antibacterial activity was isolated from marine water, identified using 16S rDNA sequence analysis as Pseudoalteromonas sp., and designated as strain M2.

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The ocean is a rich resource of flora, fauna, and food. A wild-type bacterial strain showing confluent growth on marine agar with antibacterial activity was isolated from marine water, identified using 16S rDNA sequence analysis as Pseudoalteromonas sp., and designated as strain M2. This strain was found to produce various secondary metabolites including quinolone alkaloids. Using high-resolution mass spectrometry (MS) and nuclear magnetic resonance (NMR) analysis, we identified nine secondary metabolites of 4-hydroxy-2-alkylquinoline (pseudane-III, IV, V, VI, VII, VIII, IX, X, and XI). Additionally, this strain produced two novel, closely related compounds, 2-isopentylqunoline-4-one and 2-(2,3-dimetylbutyl)qunoline-4-(1H)-one, which have not been previously reported from marine bacteria. From the metabolites produced by Pseudoalteromonas sp. M2, 2-(2,3-dimethylbutyl)quinolin-4-one, pseudane-VI, and pseudane-VII inhibited melanin synthesis in Melan-A cells by 23.0%, 28.2%, and 42.7%, respectively, wherein pseudane-VII showed the highest inhibition at 8 µg/mL. The results of this study suggest that liquid chromatography (LC)-MS/MS-based metabolite screening effectively improves the efficiency of novel metabolite discovery. Additionally, these compounds are promising candidates for further bioactivity development. Full article

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Open AccessArticle Analysis of Indole Alkaloids from Rhazya stricta Hairy Roots by Ultra-Performance Liquid Chromatography-Mass Spectrometry

by Amir Akhgari, Into Laakso, Tuulikki Seppänen-Laakso, Teijo Yrjönen, Heikki Vuorela, Kirsi-Marja Oksman-Caldentey and Heiko Rischer

Molecules 2015, 20(12), 22621-22634; doi:10.3390/molecules201219873

Received: 28 October 2015 / Revised: 10 December 2015 / Accepted: 11 December 2015 / Published: 17 December 2015

Abstract

Rhazya stricta Decne. (Apocynaceae) contains a large number of terpenoid indole alkaloids (TIAs). This study focused on the composition of alkaloids obtained from transformed hairy root cultures of R. stricta employing ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). In the UPLC-MS analyses, a total of

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Rhazya stricta Decne. (Apocynaceae) contains a large number of terpenoid indole alkaloids (TIAs). This study focused on the composition of alkaloids obtained from transformed hairy root cultures of R. stricta employing ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). In the UPLC-MS analyses, a total of 20 TIAs were identified from crude extracts. Eburenine and vincanine were the main alkaloids followed by polar glucoalkaloids, strictosidine lactam and strictosidine. Secodine-type alkaloids, tetrahydrosecodinol, tetrahydro- and dihydrosecodine were detected too. The occurrence of tetrahydrosecodinol was confirmed for the first time for R. stricta. Furthermore, two isomers of yohimbine, serpentine and vallesiachotamine were identified. The study shows that a characteristic pattern of biosynthetically related TIAs can be monitored in Rhazya hairy root crude extract by this chromatographic method. Full article

(This article belongs to the Section Natural Products)

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Open AccessArticle Three-Dimensional Electro-Sonic Flow Focusing Ionization Microfluidic Chip for Mass Spectrometry

by Cilong Yu, Xiang Qian, Yan Chen, Quan Yu, Kai Ni and Xiaohao Wang

Micromachines 2015, 6(12), 1890-1902; doi:10.3390/mi6121463

Received: 9 November 2015 / Revised: 30 November 2015 / Accepted: 1 December 2015 / Published: 4 December 2015

Abstract

Increasing research efforts have been recently devoted to the coupling of microfluidic chip-integrated ionization sources to mass spectrometry (MS). Considering the limitations of microfluidic chips coupled with MS such as liquid spreading, dead volume, and manufacturing troubles, this paper proposed a new three-dimensional

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Increasing research efforts have been recently devoted to the coupling of microfluidic chip-integrated ionization sources to mass spectrometry (MS). Considering the limitations of microfluidic chips coupled with MS such as liquid spreading, dead volume, and manufacturing troubles, this paper proposed a new three-dimensional (3D) flow focusing (FF)-based microfluidic ionizing source. This source was fabricated by using the two-layer soft lithography method with the nozzle placed inside the chip. The proposed FF microfluidic chip can realize two-phase FF with liquid in air regardless of the viscosity ratio of the continuous and dispersed phases. MS results indicated that the proposed FF microfluidic chip can work as a typical electrical ionization source when supplied with high voltage and can serve as a sonic ionization source without high voltage. The electro-sonic FF ionization microfluidic chip is expected to have various applications, particularly in the integrated and portable applications of ionization sources coupling with portable MS in the future. Full article

(This article belongs to the Special Issue Micro/Nano Devices for Chemical Analysis)

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Open AccessArticle Mass Spectrometry-Based Method of Detecting and Distinguishing Type 1 and Type 2 Shiga-Like Toxins in Human Serum

by Christopher J. Silva, Melissa L. Erickson-Beltran, Craig B. Skinner, Stephanie A. Patfield and Xiaohua He

Toxins 2015, 7(12), 5236-5253; doi:10.3390/toxins7124875

Received: 29 September 2015 / Revised: 28 October 2015 / Accepted: 9 November 2015 / Published: 2 December 2015

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Abstract

Shiga-like toxins (verotoxins) are responsible for the virulence associated with a variety of foodborne bacterial pathogens. Direct detection of toxins requires a specific and sensitive technique. In this study, we describe a mass spectrometry-based method of analyzing the tryptic decapeptides derived from the

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Shiga-like toxins (verotoxins) are responsible for the virulence associated with a variety of foodborne bacterial pathogens. Direct detection of toxins requires a specific and sensitive technique. In this study, we describe a mass spectrometry-based method of analyzing the tryptic decapeptides derived from the non-toxic B subunits. A gene encoding a single protein that yields a set of relevant peptides upon digestion with trypsin was designed. The ¹⁵N-labeled protein was prepared by growing the expressing bacteria in minimal medium supplemented with ¹⁵NH₄Cl. Trypsin digestion of the ¹⁵N-labeled protein yields a set of ¹⁵N-labeled peptides for use as internal standards to identify and quantify Shiga or Shiga-like toxins. We determined that this approach can be used to detect, quantify and distinguish among the known Shiga toxins (Stx) and Shiga-like toxins (Stx1 and Stx2) in the low attomole range (per injection) in complex media, including human serum. Furthermore, Stx1a could be detected and distinguished from the newly identified Stx1e in complex media. As new Shiga-like toxins are identified, this approach can be readily modified to detect them. Since intact toxins are digested with trypsin prior to analysis, the handling of intact Shiga toxins is minimized. The analysis can be accomplished within 5 h. Full article

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Open AccessArticle Optimization of Sample Preparation for the Identification and Quantification of Saxitoxin in Proficiency Test Mussel Sample using Liquid Chromatography-Tandem Mass Spectrometry

by Kirsi Harju, Marja-Leena Rapinoja, Marc-André Avondet, Werner Arnold, Martin Schär, Stephen Burrell, Werner Luginbühl and Paula Vanninen

Toxins 2015, 7(12), 4868-4880; doi:10.3390/toxins7124853

Received: 18 June 2015 / Revised: 30 July 2015 / Accepted: 4 August 2015 / Published: 25 November 2015

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Abstract

Saxitoxin (STX) and some selected paralytic shellfish poisoning (PSP) analogues in mussel samples were identified and quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Sample extraction and purification methods of mussel sample were optimized for LC-MS/MS analysis. The developed method was applied to the

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Saxitoxin (STX) and some selected paralytic shellfish poisoning (PSP) analogues in mussel samples were identified and quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Sample extraction and purification methods of mussel sample were optimized for LC-MS/MS analysis. The developed method was applied to the analysis of the homogenized mussel samples in the proficiency test (PT) within the EQuATox project (Establishment of Quality Assurance for the Detection of Biological Toxins of Potential Bioterrorism Risk). Ten laboratories from eight countries participated in the STX PT. Identification of PSP toxins in naturally contaminated mussel samples was performed by comparison of product ion spectra and retention times with those of reference standards. The quantitative results were obtained with LC-MS/MS by spiking reference standards in toxic mussel extracts. The results were within the z-score of ±1 when compared to the results measured with the official AOAC (Association of Official Analytical Chemists) method 2005.06, pre-column oxidation high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Full article

(This article belongs to the Special Issue Detection and identification of biological toxins in international proficiency tests)

Open AccessArticle Comparative Lipidomics of Caenorhabditis elegans Metabolic Disease Models by SWATH Non-Targeted Tandem Mass Spectrometry

by Jeevan K. Prasain, Landon Wilson, Hieu D. Hoang, Ray Moore and Michael A. Miller

Metabolites 2015, 5(4), 677-696; doi:10.3390/metabo5040677

Received: 30 September 2015 / Revised: 29 October 2015 / Accepted: 4 November 2015 / Published: 11 November 2015

Abstract

Tandem mass spectrometry (MS/MS) with Sequential Window Acquisition of all Theoretical (SWATH) mass spectra generates a comprehensive archive of lipid species within an extract for retrospective, quantitative MS/MS analysis. Here we apply this new technology in Caenorhabditis elegans (C. elegans) to

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Tandem mass spectrometry (MS/MS) with Sequential Window Acquisition of all Theoretical (SWATH) mass spectra generates a comprehensive archive of lipid species within an extract for retrospective, quantitative MS/MS analysis. Here we apply this new technology in Caenorhabditis elegans (C. elegans) to identify potential lipid mediators and pathways. The DAF-1 type I TGF-β and DAF-2 insulin receptors transmit endocrine signals that couple metabolic status to fertility and lifespan. Mutations in daf-1 and daf-2 reduce prostaglandin-endoperoxide synthase (i.e., Cox)-independent prostaglandin synthesis, increase triacylglyceride storage, and alter transcription of numerous lipid metabolism genes. However, the extent to which DAF-1 and DAF-2 signaling modulate lipid metabolism and the underlying mechanisms are not well understood. MS/MSALL with SWATH analysis across the groups identified significant changes in numerous lipids, including specific triacylglycerols, diacylglycerols, and phosphatidylinositols. Examples are provided, using retrospective neutral loss and precursor ion scans as well as MS/MS spectra, to help identify annotated lipids and search libraries for lipids of interest. As proof of principle, we used comparative lipidomics to investigate the prostaglandin metabolism pathway. SWATH data support an unanticipated model: Cox-independent prostaglandin synthesis may involve lysophosphatidylcholine and other lyso glycerophospholipids. This study showcases the power of comprehensive, retrospectively searchable lipid archives as a systems approach for biological discovery in genetic animal models. Full article

Open AccessArticle The Occurrence of Propyl Lactate in Chinese Baijius (Chinese Liquors) Detected by Direct Injection Coupled with Gas Chromatography-Mass Spectrometry

by Jihong Wu, Yang Zheng, Baoguo Sun, Xiaotao Sun, Jiyuan Sun, Fuping Zheng and Mingquan Huang

Molecules 2015, 20(10), 19002-19013; doi:10.3390/molecules201019002

Received: 1 September 2015 / Revised: 7 October 2015 / Accepted: 13 October 2015 / Published: 19 October 2015

Cited by 2 | Viewed by 928 | PDF Full-text (1106 KB) | HTML Full-text | XML Full-text

Abstract

As one of the oldest distillates in the world, flavor compounds of Chinese Baijiu (Chinese liquor) were extremely complex. Propyl lactate was ﬁrstly detected by direct injection and gas chromatography-mass spectrometry (GC-MS) in 72 Chinese Baijius. The objectives were to detect the contents

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As one of the oldest distillates in the world, flavor compounds of Chinese Baijiu (Chinese liquor) were extremely complex. Propyl lactate was ﬁrstly detected by direct injection and gas chromatography-mass spectrometry (GC-MS) in 72 Chinese Baijius. The objectives were to detect the contents of propyl lactate and evaluate its contribution to the aroma of Chinese Baijiu based on odor activity values (OAVs). The levels of propyl lactate in these distillates were determined by internal standard method and selective ion monitoring (SIM), which ranged from 0.050 to 1.900 mg∙L⁻¹ under investigation. Its detection threshold was determined by Three-Alternative Forced-Choice (3-AFC) and curve fitting (CF), which was 0.740 mg∙L⁻¹ in 38% ethanol solution. The contribution of propyl lactate on the aroma of these distillate drinks was evaluated by their odor activity values (OAVs), which varied from 0.066 to 4.440. The OAVs of propyl lactate were found to exceed 1 in 13 Chinese Baijius, including 50° Jingzhi Guniang 5 years (4.440), 52° Jingzhi Guniang 10 years (3.024), Jingyanggang (2.568), Xianghe Ronghe Shaofang (2.313), and 1956 Laolang (1.431), which indicated that propyl lactate was one of odor-active components in these Chinese Baijius. Full article

(This article belongs to the collection Recent Advances in Flavors and Fragrances)

Open AccessArticle Antiproliferative and Apoptotic Activity of Chamaecyparis obtusa Leaf Extract against the HCT116 Human Colorectal Cancer Cell Line and Investigation of the Bioactive Compound by Gas Chromatography-Mass Spectrometry-Based Metabolomics

by Hye-Youn Kim, Seul-Gi Lee, Taek-Joo Oh, Sa Rang Lim, So-Hyun Kim, Hong Jin Lee, Young-Suk Kim and Hyung-Kyoon Choi

Molecules 2015, 20(10), 18066-18082; doi:10.3390/molecules201018066

Received: 4 September 2015 / Revised: 21 September 2015 / Accepted: 29 September 2015 / Published: 2 October 2015

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Abstract

Chamaecyparis obtusa (CO) belongs to the Cupressaceae family, and it is found widely distributed in Japan and Korea. In this study, the anti-proliferative activities of the methanol and water extracts of CO leaves against a human colorectal cancer cell line (HCT116) were investigated.

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Chamaecyparis obtusa (CO) belongs to the Cupressaceae family, and it is found widely distributed in Japan and Korea. In this study, the anti-proliferative activities of the methanol and water extracts of CO leaves against a human colorectal cancer cell line (HCT116) were investigated. The methanol extract of CO leaves, at a concentration of 1.25 µg/mL, exhibited anti-proliferative activity against HCT116 cells, while displaying no cytotoxicity against Chang liver cells. Comparative global metabolite profiling was performed using gas chromatography-mass spectrometry coupled with multivariate statistical analysis, and it was revealed that anthricin was the major compound contributing to the anti-proliferative activity. The activation of c-Jun N-terminal kinases played a key role in the apoptotic effect of the methanol extract of CO leaves in HCT116 human colon cancer cells. These results suggest that the methanol extract and anthricin derived from CO leaves might be useful in the development of medicines with anti-colorectal cancer activity. Full article

(This article belongs to the Special Issue Applications of Metabolomics within Natural Products Chemistry)

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Open AccessArticle Automated Analysis of Oxytocin by On-Line in-Tube Solid-Phase Microextraction Coupled with Liquid Chromatography-Tandem Mass Spectrometry

by Eri Moriyama and Hiroyuki Kataoka

Chromatography 2015, 2(3), 382-391; doi:10.3390/chromatography2030382

Received: 12 May 2015 / Revised: 21 June 2015 / Accepted: 26 June 2015 / Published: 30 June 2015

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Abstract

A simple and sensitive method for the analysis of oxytocin was developed using automated on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC–MS/MS). Oxytocin was separated within 3 min on a Zorbax Eclipse XDB-C8 column, with water/methanol (10/90, v/v) as

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A simple and sensitive method for the analysis of oxytocin was developed using automated on-line in-tube solid-phase microextraction (SPME) coupled with liquid chromatography-tandem mass spectrometry (LC–MS/MS). Oxytocin was separated within 3 min on a Zorbax Eclipse XDB-C8 column, with water/methanol (10/90, v/v) as the mobile phase at a flow rate of 0.2 mL min⁻¹. Electrospray ionization conditions in the positive ion mode were optimized for MS/MS detection by multiple reaction monitoring. The optimum in-tube SPME conditions were 20 draw/eject cycles of 40 µL sample at a flow rate of 250 µL min⁻¹ using a Supel-Q PLOT capillary column as an extraction device. The extracted oxytocin was easily desorbed from the capillary by passage of the mobile phase, and no carryover was observed. The calibration curves for oxytocin were linear (r = 0.9981) in the range of 0−5.0 ng mL⁻¹, and the relative standard deviations at each point were below 14.7% (n = 3). The limit of detection of this method was 4.0 pg mL⁻¹, and its sensitivity was 58-fold higher than that of the direct injection method. This method was applied successfully to the analysis of oxytocin in saliva samples without any other interference peaks. Full article

(This article belongs to the Special Issue Solid Phase Micro-Extraction)

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Open AccessArticle Structural Characterization of New Peptide Variants Produced by Cyanobacteria from the Brazilian Atlantic Coastal Forest Using Liquid Chromatography Coupled to Quadrupole Time-of-Flight Tandem Mass Spectrometry

by Miriam Sanz, Ana Paula Dini Andreote, Marli Fatima Fiore, Felipe Augusto Dörr and Ernani Pinto

Mar. Drugs 2015, 13(6), 3892-3919; doi:10.3390/md13063892

Received: 26 February 2015 / Revised: 14 May 2015 / Accepted: 21 May 2015 / Published: 18 June 2015

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Abstract

Cyanobacteria from underexplored and extreme habitats are attracting increasing attention in the search for new bioactive substances. However, cyanobacterial communities from tropical and subtropical regions are still largely unknown, especially with respect to metabolite production. Among the structurally diverse secondary metabolites produced by

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Cyanobacteria from underexplored and extreme habitats are attracting increasing attention in the search for new bioactive substances. However, cyanobacterial communities from tropical and subtropical regions are still largely unknown, especially with respect to metabolite production. Among the structurally diverse secondary metabolites produced by these organisms, peptides are by far the most frequently described structures. In this work, liquid chromatography/electrospray ionization coupled to high resolution quadrupole time-of-flight tandem mass spectrometry with positive ion detection was applied to study the peptide profile of a group of cyanobacteria isolated from the Southeastern Brazilian coastal forest. A total of 38 peptides belonging to three different families (anabaenopeptins, aeruginosins, and cyanopeptolins) were detected in the extracts. Of the 38 peptides, 37 were detected here for the first time. New structural features were proposed based on mass accuracy data and isotopic patterns derived from full scan and MS/MS spectra. Interestingly, of the 40 surveyed strains only nine were confirmed to be peptide producers; all of these strains belonged to the order Nostocales (three Nostoc sp., two Desmonostoc sp. and four Brasilonema sp.). Full article

(This article belongs to the Special Issue Compounds from Cyanobacteria)

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Open AccessArticle Employing Response Surface Methodology for the Optimization of Ultrasound Assisted Extraction of Lutein and β-Carotene from Spinach

by Ammar Altemimi, David A. Lightfoot, Mary Kinsel and Dennis G. Watson

Molecules 2015, 20(4), 6611-6625; doi:10.3390/molecules20046611

Received: 6 February 2015 / Revised: 8 April 2015 / Accepted: 10 April 2015 / Published: 14 April 2015

Cited by 5 | Viewed by 1516 | PDF Full-text (2400 KB) | HTML Full-text | XML Full-text

Abstract

The extraction of lutein and β-carotene from spinach (Spinacia oleracea L.) leaves is important to the dietary supplement industry. A Box-Behnken design and response surface methodology (RSM) were used to investigate the effect of process variables on the ultrasound-assisted extraction (UAE) of

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The extraction of lutein and β-carotene from spinach (Spinacia oleracea L.) leaves is important to the dietary supplement industry. A Box-Behnken design and response surface methodology (RSM) were used to investigate the effect of process variables on the ultrasound-assisted extraction (UAE) of lutein and β-carotene from spinach. Three independent variables, extraction temperature (°C), extraction power (%) and extraction time (min) were studied. Thin-layer chromatography (TLC) followed by UV visualization and densitometry was used as a simple and rapid method for both identification and quantification of lutein and β-carotene during UAE. Methanol extracts of leaves from spinach and authentic standards of lutein and β-carotene were separated by normal-phase TLC with ethyl acetate-acetone (5:4 (v/v)) as the mobile phase. In this study, the combination of TLC, densitometry, and Box–Behnken with RSM methods were effective for the quantitative analysis of lutein and β-carotene from spinach extracts. The resulting quadratic polynomial models for optimizing lutein and β-carotene from spinach had high coefficients of determination of 0.96 and 0.94, respectively. The optimal UAE settings for output of lutein and β-carotene simultaneously from spinach extracts were an extraction temperature of 40 °C, extraction power of 40% (28 W/cm³) and extraction time of 16 min. The identity and purity of each TLC spot was measured using time-of-flight mass spectrometry. Therefore, UAE assisted extraction of carotenes from spinach can provide a source of lutein and β-carotene for the dietary supplement industry. Full article

(This article belongs to the Special Issue New Technologies for the Recovery of Natural Products)

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Open AccessCommunication Solvent Separating Secondary Metabolites Directly from Biosynthetic Tissue for Surface-Assisted Laser Desorption Ionisation Mass Spectrometry

by David Rudd, Kirsten Benkendorff and Nicolas H. Voelcker

Mar. Drugs 2015, 13(3), 1410-1431; doi:10.3390/md13031410

Received: 30 November 2014 / Revised: 13 February 2015 / Accepted: 2 March 2015 / Published: 16 March 2015

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Abstract

Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry

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Marine bioactive metabolites are often heterogeneously expressed in tissues both spatially and over time. Therefore, traditional solvent extraction methods benefit from an understanding of the in situ sites of biosynthesis and storage to deal with heterogeneity and maximize yield. Recently, surface-assisted mass spectrometry (MS) methods namely nanostructure-assisted laser desorption ionisation (NALDI) and desorption ionisation on porous silicon (DIOS) surfaces have been developed to enable the direct detection of low molecular weight metabolites. Since direct tissue NALDI-MS or DIOS-MS produce complex spectra due to the wide variety of other metabolites and fragments present in the low mass range, we report here the use of “on surface” solvent separation directly from mollusc tissue onto nanostructured surfaces for MS analysis, as a mechanism for simplifying data annotation and detecting possible artefacts from compound delocalization during the preparative steps. Water, ethanol, chloroform and hexane selectively extracted a range of choline esters, brominated indoles and lipids from Dicathais orbita hypobranchial tissue imprints. These compounds could be quantified on the nanostructured surfaces by comparison to standard curves generated from the pure compounds. Surface-assisted MS could have broad utility for detecting a broad range of secondary metabolites in complex marine tissue samples. Full article

(This article belongs to the Special Issue Marine Natural Products - Advances in Separation, Characterisation and Chemical Profiling Methodologies)

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Open AccessTechnical Note High-Throughput Mass Spectrometry Applied to Structural Genomics

by Rod Chalk, Georgina Berridge, Leela Shrestha, Claire Strain-Damerell, Pravin Mahajan, Wyatt W. Yue, Opher Gileadi and Nicola A. Burgess-Brown

Chromatography 2014, 1(4), 159-175; doi:10.3390/chromatography1040159

Received: 1 July 2014 / Revised: 3 September 2014 / Accepted: 11 September 2014 / Published: 9 October 2014

Viewed by 1636 | PDF Full-text (1100 KB) | HTML Full-text | XML Full-text | Supplementary Files

Abstract

Mass spectrometry (MS) remains under-utilized for the analysis of expressed proteins because it is inaccessible to the non-specialist, and sample-turnaround from service labs is slow. Here, we describe 3.5 min Liquid-Chromatography (LC)-MS and 16 min LC-MSMS methods which are tailored to validation and

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Mass spectrometry (MS) remains under-utilized for the analysis of expressed proteins because it is inaccessible to the non-specialist, and sample-turnaround from service labs is slow. Here, we describe 3.5 min Liquid-Chromatography (LC)-MS and 16 min LC-MSMS methods which are tailored to validation and characterization of recombinant proteins in a high throughput structural biology pipeline. We illustrate the type and scope of MS data typically obtained from a 96-well expression and purification test for both soluble and integral membrane proteins (IMPs), and describe their utility in the selection of constructs for scale-up structural work, leading to cost and efficiency savings. We propose that value of MS data lies in how quickly it becomes available and that this can fundamentally change the way in which it is used. Full article

(This article belongs to the Special Issue Recent Advancements in Analysis of Biomolecules with Separation Technologies)

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Open AccessArticle Continuous Flow Atmospheric Pressure Laser Desorption/Ionization Using a 6–7-µm-Band Mid-Infrared Tunable Laser for Biomolecular Mass Spectrometry

by Ryuji Hiraguchi, Hisanao Hazama, Kenichirou Senoo, Yukinori Yahata, Katsuyoshi Masuda and Kunio Awazu

Int. J. Mol. Sci. 2014, 15(6), 10821-10834; doi:10.3390/ijms150610821

Received: 20 March 2014 / Revised: 28 May 2014 / Accepted: 4 June 2014 / Published: 16 June 2014

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Abstract

A continuous flow atmospheric pressure laser desorption/ionization technique using a porous stainless steel probe and a 6–7-µm-band mid-infrared tunable laser was developed. This ion source is capable of direct ionization from a continuous flow with a high temporal stability. The 6–7-µm wavelength region

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A continuous flow atmospheric pressure laser desorption/ionization technique using a porous stainless steel probe and a 6–7-µm-band mid-infrared tunable laser was developed. This ion source is capable of direct ionization from a continuous flow with a high temporal stability. The 6–7-µm wavelength region corresponds to the characteristic absorption bands of various molecular vibration modes, including O–H, C=O, CH₃ and C–N bonds. Consequently, many organic compounds and solvents, including water, have characteristic absorption peaks in this region. This ion source requires no additional matrix, and utilizes water or acetonitrile as the solvent matrix at several absorption peak wavelengths (6.05 and 7.27 µm, respectively). The distribution of multiply-charged peptide ions is extremely sensitive to the temperature of the heated capillary, which is the inlet of the mass spectrometer. This ionization technique has potential for the interface of liquid chromatography/mass spectrometry (LC/MS). Full article

(This article belongs to the Special Issue Mass Spectrometry Application in Biology) Printed Edition available

Open AccessArticle Investigation of Non-Enzymatic Glycosylation of Human Serum Albumin Using Ion Trap-Time of Flight Mass Spectrometry

by Xue Bai, Zhangjie Wang, Chengcai Huang, Zhe Wang and Lianli Chi

Molecules 2012, 17(8), 8782-8794; doi:10.3390/molecules17088782

Received: 4 June 2012 / Revised: 8 July 2012 / Accepted: 13 July 2012 / Published: 25 July 2012

Cited by 13 | Viewed by 2800 | PDF Full-text (772 KB) | Supplementary Files

Abstract

Non-enzymatic glycosylation or glycation involves covalent attachment of reducing sugar residues to proteins without enzyme participation. Glycation of glucose to human serum albumin in vivo is related to diabetes and many other diseases. We present an approach using liquid chromatography coupled to an

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Non-enzymatic glycosylation or glycation involves covalent attachment of reducing sugar residues to proteins without enzyme participation. Glycation of glucose to human serum albumin in vivo is related to diabetes and many other diseases. We present an approach using liquid chromatography coupled to an electrospray ionization source of a hybrid ion trap-time of flight (IT-TOF-MS/MS) tandem mass spectrometer to identify the glycation sites on serum albumin from both a healthy person and a diabetic patient. The MetID software, which is commonly used for screening metabolites, is adapted for peptide fingerprinting based on both m/z values and isotopic distribution profiles. A total of 21 glycation sites from the healthy person and 16 glycation sites from the diabetic patient were identified successfully. We also demonstrate the use of matrix assisted laser desorption ionization-time of flight mass spectrometry to estimate the incorporation ratio of glucose to albumin during glycation. Results from this study show that the glycation in healthy person is more complicated than previously thought. Further analysis of incorporation ratio distribution may be necessary to accurately reflect the change of serum albumin glycation in diabetic patients. Full article

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Open AccessArticle Chemical Investigation of Saponins in Different Parts of Panax notoginseng by Pressurized Liquid Extraction and Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry

by Jian-Bo Wan, Qing-Wen Zhang, Si-Jia Hong, Peng Li, Shao-Ping Li and Yi-Tao Wang

Molecules 2012, 17(5), 5836-5853; doi:10.3390/molecules17055836

Received: 12 April 2012 / Revised: 3 May 2012 / Accepted: 11 May 2012 / Published: 16 May 2012

Cited by 21 | Viewed by 3666 | PDF Full-text (527 KB)

Abstract

A pressurized liquid extraction (PLE) and high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed for the qualitative determination of saponins in different parts of P. notoginseng, including rhizome, root, fibre root, seed, stem, leaf and flower. The samples

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A pressurized liquid extraction (PLE) and high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) method was developed for the qualitative determination of saponins in different parts of P. notoginseng, including rhizome, root, fibre root, seed, stem, leaf and flower. The samples were extracted using PLE. The analysis was achieved on a Zorbax SB-C18 column with gradient elution of acetonitrile and 8 mM aqueous ammonium acetate as mobile phase. The mass spectrometer was operated in the negative ion mode using the electrospray ionization, and a collision induced dissociation (CID) experiment was also carried out to aid the identification of compounds. Forty one saponins were identified in different parts of P. notoginseng according to the fragmentation patterns and literature reports, among them, 21 saponins were confirmed by comparing the retention time and ESI-MS data with those of standard compounds. The results showed that the chemical characteristics were obviously diverse in different parts of P. notoginseng, which is helpful for pharmacological evaluation and quality control of P. notoginseng. Full article

(This article belongs to the Section Natural Products)

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Open AccessArticle Fast Direct Injection Mass-Spectrometric Characterization of Stimuli for Insect Electrophysiology by Proton Transfer Reaction-Time of Flight Mass-Spectrometry (PTR-ToF-MS)

by Marco Tasin, Luca Cappellin and Franco Biasioli

Sensors 2012, 12(4), 4091-4104; doi:10.3390/s120404091

Received: 21 January 2012 / Revised: 14 March 2012 / Accepted: 22 March 2012 / Published: 27 March 2012

Cited by 6 | Viewed by 2578 | PDF Full-text (340 KB) | HTML Full-text | XML Full-text

Abstract

Electrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound

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Electrophysiological techniques are used in insect neuroscience to measure the response of olfactory neurons to volatile odour stimuli. Widely used systems to deliver an olfactory stimulus to a test insect include airstream guided flow through glass cartridges loaded with a given volatile compound on a sorbent support. Precise measurement of the quantity of compound reaching the sensory organ of the test organism is an urgent task in insect electrophysiology. In this study we evaluated the performances of the recent realised proton transfer reaction-time of flight mass-spectrometry (PTR-ToF-MS) as a fast and selective gas sensor. In particular, we characterised the gas emission from cartridges loaded with a set of volatile compounds belonging to different chemical classes and commonly used in electrophysiological experiments. PTR-ToF-MS allowed a fast monitoring of all investigated compounds with sufficient sensitivity and time resolution. The detection and the quantification of air contaminants and solvent or synthetic standards impurities allowed a precise quantification of the stimulus exiting the cartridge. The outcome of this study was twofold: on one hand we showed that PTR-ToF-MS allows monitoring fast processes with high sensitivity by real time detection of a broad number of compounds; on the other hand we provided a tool to solve an important issue in insect electrophysiology. Full article

(This article belongs to the Special Issue Odor Detection: Electronic Nose, Olfactometer, and Advanced Instrumentation)

Open AccessArticle Observation of T-2 Toxin and HT-2 Toxin Glucosides from Fusarium sporotrichioides by Liquid Chromatography Coupled to Tandem Mass Spectrometry (LC-MS/MS)

by Mark Busman, Stephen M. Poling and Chris M. Maragos

Toxins 2011, 3(12), 1554-1568; doi:10.3390/toxins3121554

Received: 24 November 2011 / Revised: 14 December 2011 / Accepted: 19 December 2011 / Published: 20 December 2011

Cited by 36 | Viewed by 2513 | PDF Full-text (482 KB) | HTML Full-text | XML Full-text

Abstract

The trichothecenes produced by solid and liquid cultures of Fusarium sporotrichioides were evaluated with high performance liquid chromatography—tandem mass spectrometry (LC-MS/MS). Along with the expected T-2 toxin HT-2 toxin and neosolaniol, two additional compounds were detected, which had ions 162 m/z higher than

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The trichothecenes produced by solid and liquid cultures of Fusarium sporotrichioides were evaluated with high performance liquid chromatography—tandem mass spectrometry (LC-MS/MS). Along with the expected T-2 toxin HT-2 toxin and neosolaniol, two additional compounds were detected, which had ions 162 m/z higher than those in the mass spectra of T-2 toxin or HT-2 toxin. Fragmentation behavior of these two compounds was similar to that of T-2 toxin and HT-2 toxin. Based on LC-MS/MS behavior, it is proposed that the two compounds are T-2 toxin 3-O-glucoside and HT-2 toxin 3-O-glucoside. Production of the two glucosides was measured in kernels from wheat and oat inoculated with F. sporotrichiodes, as well as in cultures grown in liquid media and on cracked corn or rice. Production of glucosides in wheat and oats suggest that they may also be present in naturally contaminated cereals. Full article

(This article belongs to the Special Issue Trichothecenes)

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Open AccessArticle Identification of Serum Biomarkers for Biliary Tract Cancers by a Proteomic Approach Based on Time-of-Flight Mass Spectrometry

by Wen-Jing Wang, Wang-Hong Xu, Cha-Zhen Liu, Asif Rashid, Jia-Rong Cheng, Ping Liao, Heng Hu, Lisa W. Chu, Yu-Tang Gao, Kai Yu and Ann W. Hsing

Cancers 2010, 2(3), 1602-1616; doi:10.3390/cancers2031602

Received: 21 June 2010 / Revised: 5 August 2010 / Accepted: 16 August 2010 / Published: 18 August 2010

Viewed by 5792 | PDF Full-text (157 KB) | HTML Full-text | XML Full-text

Abstract

Biliary tract cancers (BTCs) are lethal malignancies currently lacking satisfactory methods for early detection and accurate diagnosis. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is a promising diagnostic tool for this disease. In this pilot study, sera samples from 50 BTCs and 30

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Biliary tract cancers (BTCs) are lethal malignancies currently lacking satisfactory methods for early detection and accurate diagnosis. Surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) is a promising diagnostic tool for this disease. In this pilot study, sera samples from 50 BTCs and 30 cholelithiasis patients as well as 30 healthy subjects from a population-based case-control study were randomly grouped into training set (30 BTCs, 20 cholelithiasis and 20 controls), duplicate of training set, and blind set (20 BTCs, 10 cholelithiasis and 10 controls); all sets were analyzed on Immobilized Metal Affinity Capture ProteinChips via SELDI-TOF-MS. A decision tree classifier was built using the training set and applied to all test sets. The classification tree constructed with the 3,400, 4,502, 5,680, 7,598, and 11,242 mass-to-charge ratio (m/z) protein peaks had a sensitivity of 96.7% and a specificity of 85.0% when comparing BTCs with non-cancers. When applied to the duplicate set, sensitivity was 66.7% and specificity was 70.0%, while in the blind set, sensitivity was 95.0% and specificity was 75.0%. Positive predictive values of the training, duplicate, and blind sets were 82.9%, 62.5% and 79.2%, respectively. The agreement of the training and duplicate sets was 71.4% (Kappa = 0.43, u = 3.98, P < 0.01). The coefficient of variations based on 10 replicates of one sample for the five differential peaks were 15.8–68.8% for intensity and 0–0.05% for m/z. These pilot results suggest that serum protein profiling by SELDI-TOF-MS may be a promising approach for identifying BTCs but low assay reproducibility may limit its application in clinical practice. Full article

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