Search results for " ionization"
showing 10 items of 621 documents
Biomonitoring of Enniatin B1 and Its Phase I Metabolites in Human Urine: First Large-Scale Study
2020
Enniatins (Enns) are mycotoxins produced by Fusarium spp. which are a fungus widely spread throughout cereals and cereal-based products. Among all the identified enniatins, Enn B1 stands as one of the most prevalent analogues in cereals in Europe. Hence, the aim of this study was to evaluate for the first time the presence of Enn B1 and its phase I metabolites in 300 human urine samples using an ultrahigh-performance liquid chromatography high resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS) methodology. Enn B1 was detected in 94.3% of samples ranging from 0.007 to 0.429 ng/mL (mean value: 0.065 ng/mL). In accordance with previous in vitro and in vivo analysis, hydroxylated metabolites …
Ciclohexadespipeptide beauvericin degradation by different strains of Saccharomyces cerevisiae
2013
Abstract The interaction between the mycotoxin beauvericin (BEA) and 9 yeast strains of Saccharomyces cerevisiae named LO9, YE-2, YE5, YE-6, YE-4, A34, A17, A42 and A08 was studied. The biological degradations were carried out under aerobic conditions in the liquid medium of Potato Dextrose Broth (PDB) at 25 °C for 48 h and in a food/feed system composed of corn flour at 37 °C for 3 days, respectively. BEA present in fermented medium and corn flour was determined using liquid chromatography coupled to the mass spectrometry detector in tandem (LC–MS/MS) and the BEA degradation products produced during the fermentations were determined using the technique of the liquid chromatography coupled …
Antibacterial activity of the enniatin B, produced by Fusarium tricinctum in liquid culture, and cytotoxic effects on Caco-2 cells.
2011
The enniatins (ENs) are bioactive compounds of hexadepsipeptidic structure produced by several strains of Fusarium sp. The EN B was purified from extracts of Fusarium tricinctum growth on liquid culture of potato dextrose broth (PDB), using a semipreparative liquid chromatography (LC) followed by an analytical LC. The purity and the structure of the isolated compound were confirmed by the determination of the extinction coefficient and with electrospray ionization-mass spectrometry (ESI-MS) study. The pure fraction of EN B was utilized to determine the antibiotic effects on several bacterial strains that are considered normally pathogens of the intestinal tract: Escherichia coli, Enterococc…
Isolation, purification and antibacterial effects of fusaproliferin produced by Fusariumsubglutinans in submerged culture.
2009
To evaluate the fusaproliferin (FUS) production, Fusariumsubglutinans ITEM 2404 was grown in a liquid medium of potato being this mycotoxin purified by high-performance liquid chromatography (HPLC) with a C18 semipreparative column using a mobile phase of acetonitrile/H(2)O using gradient conditions. The purity of the fusaproliferin was verified by analytical HPLC, ultraviolet absorbance measurements, LC/MS-MS, (1)H NMR spectroscopy. The isolated FUS was shown to be free of impurities and can be used as a standard for routine analysis. The pure fusaproliferin was utilized to study the biological activity on Escherichiacoli and Staphylococcusaureus. This study demostred that FUS not showed s…
Study of the chemical reduction of the fumonisins toxicity using allyl, benzyl and phenyl isothiocyanate in model solution and in food products
2012
Abstract Fumonisins (FBs) are bioactive compounds produced by several strains of Fusarium spp. which contain a polyketide structure similar to sphinganine. These mycotoxins contain a free amino group that could work as an electron donor and react with the electrophile carbon present within the isothiocyanate (ITC) group. The objective of this study was to determine the effect of ITCs (allyl, benzyl and phenyl) on the stability of FB 1 , FB 2 and FB 3 . Firstly, PBS solutions at three pH levels (4, 7 and 9) were prepared and added with pairs of one FB (1 mg/L) plus one ITC (1 mg/L). Then, gaseous ITC was used to fumigate corn kernels and corn flour contaminated with FBs produced by Gibberell…
Strukturuntersuchung von polyestern durch direkten abbau im massenspektrometer, 3. Poly-β-propiolacton, poly-β-pivalolacton und poly-δ-valerolacton
1978
Poly(oxycarbonylethylene) (poly-β-propiolactone), poly(oxycarbonyl-1,1-dimeothylethylene) (poly-β-pivalolactone), and poly(oxycarbonyltetramethylene) (poly-δ-valerolactone) were pyrolyzed directly in the ion source of a mass spectrometer and their thermal and electron impact induced degradation mechanisms are established. Poly-β-propiolactone is thermally degraded by rupture of the OCH2-bond by a cis elimination to give carboxyl and acryloyl endgroups, whereas poly-δ-valerolactone depolymerizes to δ-valerolactone. Poly-β-pivalolactone degrades thermally to cyclic oligomers of pivalolactone, which could be proved by a separated pyrolysis and IR-spectroscopy and gel chromatography.
1 H,13 C, 19 F NMR, and ESI mass spectral characterization of two geminal difluorosteroids
2008
Two geminal difluorosteroids, 3,3-difluoro-5β-cholan-24-oic acid (1) and 3,3-difluoro-5α-androstan-17-one (2), have been prepared from corresponding ketosteroids with diethylaminosulphurtrifluoride (DAST) treatment in moderate yields. The structures of 1 and 2 have been characterized by 1H, 13C, 19F NMR, and ESI mass spectral techniques. Copyright © 2008 John Wiley & Sons, Ltd.
Identification and cloning of odorant binding proteins from the scarab beetle Phyllopertha diversa.
1999
Abstract Wehave identified, cloned, and characterized two odorant binding proteins from the pale brown chafer, Phyllopertha diversa. One of the proteins (OBP1, 116 amino acids long) showed high amino acid identity (>90%) to two previously identified PBPs from scarab beetles. The second protein (OBP2) showed limited sequence similarity to lepidopteran and dipteran OBPs, but contained only 133 amino acids. Both proteins showed the occurrence of six highly conserved cysteines; electrospray mass spectral data suggested they are all bound in three disulfide bonds. During purification, OBP2 separated into several isoforms; N-terminal amino acid sequencing and electrospray ionization mass spectrom…
The metal binding abilities of Megathura crenulata metallothionein (McMT) in the frame of gastropoda MTs.
2011
Metallothioneins (MTs) are proteins that play a major role in metal homeostasis and/or detoxification in all kind of organisms. The MT gene/protein system of gastropod molluscs provides an invaluable model to study the diversification mechanisms that have enabled MTs to achieve metal-binding specificity through evolution. Most pulmonate gastropods, particularly terrestrial snails, harbor three paralogous isogenes encoding three MT isoforms with different metal binding preferences: the highly specific CdMT and CuMT isoforms, for cadmium and copper respectively, and the unspecific Cd/CuMT isoform. Megathura crenulata is a non-pulmonate gastropod in which only one MT isogene has so far been re…
Two new triterpenoid saponins fromPittosporum senaciaPutterlick (Pittosporaceae)
2012
From the branches of Pittosporum senacia Putterlick (Pittosporaceae), two new triterpenoid saponins, senaciapittosides A and B (1, 2), were isolated. Their structures were elucidated by extensive analysis of one- and two-dimensional nuclear magnetic resonance spectroscopy, high-resolution electrospray ionization mass spectrometry (HR-ESIMS) and chemical evidence as 3-O-[β-d-glucopyranosyl-(1 2)]-[α-l-arabinopyranosyl-(1 3)]-[α-l-arabinofuranosyl-(1 4)]-β-d-glucuronopyranosyl oleanolic acid 28-O-β-d-glucopyranosyl ester (1) and 3-O-[β-d-glucopyranosyl-(1 2)]-[α-l-arabinopyranosyl-(1 3)]-[α-l-arabinofuranosyl-(1 4)]-β-d-glucuronopyranosyl-22-O-α-l-arabinopyranosyl-21-acetoxy R1-barrigen…