Resolution Electron Impact Mass Research Articles

Identification and characterization of a long-chain N-acyl homoserine lactone from Rhizobium sp. isolated from Zea x mays rhizosphere

The microbiological study of maize rhizosphere (Zea x mays) cultivated in Brazil led to the isolation of a bacterium, which was identified as Rhizobium sp. based upon 16 S rRNA analysis. The chemical study of fractions obtained from bacterium extract allowed the identification of the compound N-(3-oxo-tetradec-7-enoyl)-homoserine lactone (1) using uni and bidimensional nuclear magnetic resonance spectroscopy (NMR), gas chromatography coupled to low resolution electron impact mass spectrometry (GC–MS), and ultra-high resolution Qq-time-of-flight mass spectrometry (UHR-QqTOF-MS). Biological assays with the strains Agrobacterium tumefasciens A136 and Chromobacterium violaceum CV026 were also performed and showed negative results, corroborating the hypothesis of production of only the long chain acyl homoserine lactone (AHL) 1, and the lack of presence of short or medium chain homologues, as observed by instrumental GC–MS and NMR analyses. The chemotaxonomic relevance of the presence of long chain AHL in Rhizobiaceae was discussed.

Antioxidant xanthones and anthraquinones isolated from a marine-derived fungus Aspergillus versicolor

Chemical examination of an EtOAc extract of cultured Aspergillus versicolor fungus from deep-sea sediments resulted in the isolation of four xanthones, eight anthraquinones and five alkaloids, including a new xanthone, oxisterigmatocystin D (1) and a new alkaloid, aspergillusine A (13). High resolution electron impact mass spectrometry (HR-EI-MS), FT-IR spectroscopy, and NMR techniques were used to elucidate the structures of these compounds, and the absolute configuration of compound 1 was established by its NMR features and coupling constant. Furthermore, the biosynthesis pathway of these xanthones and anthraquinones were deduced, and their antioxidant activity and cytotoxicity in human cancer cell lines (HTC-8, Bel-7420, BGC-823, A549, and A2780) were evaluated. The trolox equivalent antioxidant capacity (TEAC) assay indicated most of the xanthones and anthraquinones possessing moderate antioxidant activities. The Nrf2-dependent luciferase reporter gene assay revealed that compounds 6, 7, 9, and 12 potentially activated the expression of Nrf2-regulated gene. In addition, compounds 5 and 11 showed weak cytotoxicity on A549 with the IC50 values of 25.97 and 25.60 μmol·L−1, respectively.

Polybrominated diphenyl ether congeners in the young-of-the-year bluefish, Pomatomus saltatrix, from several nursery habitats along the US Atlantic coastline

Spatial trends of polybrominated diphenyl ether (PBDE) congeners were examined by using high resolution gas chromatography – low resolution electron impact mass spectrometry (GC-EIMS) in 414 samples of young-of-the-year (YOY) bluefish (Pomatomus saltatrix) collected from a total of 29 nursery habitats along the US Atlantic coastline from Massachusetts to Florida. Of the 26 target PBDE congeners, BDE-47 (4 Br), BDE-100 (5 Br), BDE-49 (4 Br), BDE-99 (5 Br), and BDE-154 (6 Br) were the five most frequently detected congeners in the order of decreasing importance. The sum of the concentrations of five major PBDE congeners, referred to as ΣPBDEs, varied between estuaries and also among samples from a given estuary. ΣPBDEs were lowest in YOY bluefish from Vineyard Sound, Nantucket Sound, Great Bay, Delaware Bay, Lynnhaven Bay, Cape Lookout, and Crescent Beach, with maximum ΣPBDE concentrations below 10ng/g wet weight. ΣPBDEs in three bluefish samples from Stamford Harbor were detected at relatively high to unusually high concentrations of 69.1, 205, and 561ng/g wet weight. ΣPBDE values for other Stamford Harbor bluefish were generally low. Highest PBDE concentrations were detected in the vicinity of industrial and urban locations within the New York – New Jersey metropolitan complex. Among them, bluefish from Newark Bay were generally the most contaminated with an average ΣPBDE value of 56.6±30.8ng/g wet weight. ΣPBDEs in bluefish from Newark Bay were numerically greater than ΣPBDEs in bluefish from all locations, however these differences were not statistically significant. Modest to good correlations between ΣPBDEs and lipids were observed for YOY bluefish from Buzzards Bay, Upper New Bedford Harbor, Lower New Bedford Harbor, Outer New Bedford Harbor, Providence Harbor, Housatonic River, Norwalk Harbor, Little Neck Bay, Newark Bay, Sandy Hook Bay, Great Bay, Delaware Bay, Patuxent River and Crescent Beach. Poor correlations between ΣPBDE and lipids were observed for bluefish from other estuaries. ΣPBDEs were not always correlated with fish length or weight. ΣPBDEs in YOY bluefish along the US Atlantic coastline modestly paralleled ΣPBDEs in mussels and oysters, from not exact but geographically loosely similar locations, reported in the NOAA Mussel Watch Program. A number of researchers who used the high resolution mass spectrometry reported additional PBDE congeners. Although PBDE congeners we report do appear to be the prominent congeners in these studies, it is likely that the comparisons will be skewed in certain instances.

Structure elucidation and NMR assignments for two amide alkaloids from a Mangrove endophytic Fungus (No. ZZF‐22)

The structure elucidations and complete (1)H and (13)C NMR assignments are reported for two new natural products: 3-benzylidene-8,8a-dihydroxy-2-methyl-hexahydro-pyrrolo[1,2-a]pyrazine-1,4-dione(1) and 4-hydroxy-6-(hydroxy-phenyl-methyl)-N-(3-methyl-butyryl)-nicotinamide (2). Both of these secondary metabolites were isolated from the fermentation medium of a Mangrove endophytic fungus. High resolution electron impact mass spectrometry (HREIMS), FT-IR Spectroscopy and NMR experiments including gCOSY, gHMQC, gHMBC and NOE were used for determination of the structures and assignments of the amide alkaloids.

Two New 5‐Deoxyflavonoids from Calliandra inermis

AbstractFor Abstract see ChemInform Abstract in Full Text.

Two new 5-deoxyflavonoids from Calliandra inermis.

Two new 5-deoxyflavonoids, 7,2',3',4'-tetramethoxyflavone (1) and 7,2',3',4'-tetramethoxyflavanone (2) together with a known flavone 7,4'-dimethoxy-3'-hydroxyflavone (3) were isolated from the whole plant of Calliandra inermis. The structures of these new compounds were elucidated by high resolution electron impact mass spectrometry (HR-EI-MS) and 1D and 2D-NMR spectral studies including 1H-1H correlation spectroscopy (COSY), heteronuclear single quantum coherence (HSQC), heteronuclear multiple bond connectivity (HMBC) and nuclear Overhauser enhancement spectroscopy (NOESY).

Raman spectroscopic and structural studies of indigo and its four 6,6′-dihalogeno analogues

The Raman and electron impact mass spectra of synthetic indigo and its four 6,6'-dihalogeno analogues are reported and discussed. The influence of varying the halogen on these Raman spectra is considered. Particular emphasis is laid on distinguishing indigo from 6,6'-dibromoindigo and differentiating between the dihalogenocompounds, so as to develop protocols for determining whether artefacts are coloured with dyes of marine or terrestrial origin and whether such artefacts are dyed with genuine "Tyrian Purple" or with dihalogenoindigo substitutes that do not contain bromine. The value of even low resolution electron impact mass spectrometry in a forensic context as a means of identifying authentic 6,6'-dibromoindigo and distinguishing it from its dihalogenoanalogues is emphasised

Camalexin accumulation in Arabis lyrata.

Inoculation of leaves of Arabis lyrata with either a bacterial pathogen Pseudomonas syringae pv. maculicola strain ES4326 or Cochliobolus carbonum, a fungal nonpathogen of A. lyrata, resulted in the accumulation of a compound with similar chromatographic and fluorescent properties to that of camalexin (I), a phytoalexin produced by Arabidopsis thaliana. A. lyrata is closely related to A. thaliana. High resolution electron impact mass spectroscopic and proton NMR analysis confirmed that the compound produced by A. lyrata is camalexin.

Synthesis and characterization of N-acetyl-L-cysteine S-conjugates of butadiene monoxide and their detection and quantitation in urine of rats and mice given butadiene monoxide.

Butadiene monoxide (BM), a mutagen and carcinogen, is the major metabolite of 1,3-butadiene in rats and mice. Because mercapturic acids (N-acetyl-L-cysteine S-conjugates) were expected in vivo metabolites of BM, reference BM-mercapturic acids were prepared by the reaction of racemic BM with N-acetyl-L-cysteine. Four isomers were purified and characterized as diastereomeric pairs of S-(2-hydroxy-3-buten-1-yl)-N-acetyl-L-cysteine (I) and S-(1-hydroxy-3-buten-2-yl)-N-acetyl-L-cysteine (II) based on analyses by 1H NMR, fast atom bombardment mass spectrometry, and high resolution electron impact mass spectrometry. Regioisomers I and II were identified in the urine of rats and mice administered (ip) BM based on GC/MS analyses performed after HPLC fractionation followed by esterification and silylation of the carboxyl and hydroxyl groups, respectively, and comparison of GC retention times with synthetic standards. S-(4-Hydroxy-2-buten-1-yl)-N-acetyl-L-cysteine, a rearrangement product formed during chemical synthesis or storage of both I and II under acidic conditions, was not detected; no other BM metabolites were evident in urine samples using this method. When rats were given BM at a dose of 71.5 to 285 mumol/kg, their urinary excretion of I and II within 8 h of BM administration exhibited linear relationships with the administered BM dose; the total amount of the BM dose excreted as combined I and II averaged 17 +/- 4% (mean +/- SD, n = 15). No metabolites were detected in urine samples collected between 8 and 24 h after BM dosing.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ analysis of a new perylene quinone in lichens by Fourier‐transform laser microprobe mass spectrometry with external source

AbstractThe application of Fourier‐transform laser microprobe mass spectrometry to lichens is described. The in situ detection of a new perylene quinone in samples of the tropical species Laurera sanguinaria Malme and Graphis haematites Fée was achieved with minimal specimen preparation. The high mass resolution and mass accuracy of the instrument eliminates the need for additional characterization of the isolated substances by high resolution electron impact mass spectrometry and direct introduction probe.

Investigation on the occurrence of polyhalogenated (Br/Cl) dibenzodioxins and dibenzofurans in cow's milk and fish tissue

Capillary column gas chromatography/medium resolution negative chemical ionization (NCI) and electron impact (EI) mass spectrometry was used for the search on the occurrence of polybrominated or mixed brominated/chlorinated dibenzo-p-dioxins (PB/C-DDs) and dibenzofurans (PB/C-DFs) in cow's milk and fish tissue. In fish tissue, a tetrabromo-DD and a tetrabromo-DF were identified, both not having the 2,3,7,8-substitution pattern. In a cow's milk sample from the vicinity of a municipal waste incinerator (MWI), four compounds were found which were tentatively identified as two tribomo, a tetrabromo and a pentabromodibenzofurans, all four non 2,3,7,8-substituted. Consequently, the TCDD-toxicity (TEQ) level in milk of cows exposed to flyash was not significantly affected by PB/C-DD/Fs.

Multispectral identification of alkyl and chloroalkyl phosphates from an industrial effluent

Multispectral techniques (gas chromatography combined with low and high resolution electron-impact mass spectrometry, low and high resolution chemical ionization mass spectrometry, and Fourier transform infrared spectroscopy) were used to identify 13 alkyl and chloroalkyl phosphates in a water sample taken from the effluent of a plant that manufactures fire-retardant chemicals. Of the 13 phosphates identified, only 4 were located in library mass spectral data bases; thus, techniques other than conventional low resolution electron-impact mass spectrometry with data base matching were required. Several of the identified phosphates are commonly used fire retardants; however, three exhibited chemical structures different from those of the commercially manufactured fire retardants and the reactants used in their synthesis.

Metabolism of isobutylnaphthyl acetic acid in rats: determination of the chemical structures of metabolites.

After oral and intravenous administration of radiolabelled isobutylnaphthyl acetic acid (INAA) to rats two metabolites were isolated from urine and plasma by HPLC. Field desorption, high resolution electron impact mass spectrometry as well as GC-MS after derivatization were used for structure elucidation and identification of the metabolites. The main biotransformation product in rat urine was found to be 5-(2'-hydroxy-2'-methyl-propyl)-1-naphthyl acetic acid (M1). The main metabolite in plasma was derived and was found to be 5-(2'-carboxypropyl)-1-naphthyl acetic acid (M2).

Intramolecular cyclizations of lysine Amadori rearrangement products

Based on the high resolution electron impact mass spectrometric studies of lysine Amadori rearrangement products and the fragments identified in their mass spectra, the effect of mono and di-glycosylation on the fragmentation pathways was studied. According to this study monoglycosylated lysines having a free amino group decompose by intramolecular cyclization reactions leading to six, five and four membered nitrogen-containing rings, whereas, disubstituted lysine decomposes through elimination of the sugar moieties with the production of pyrans and sugar fragments.

Atpenins, new antifungal antibiotics produced by Penicillium sp. Production, isolation, physico-chemical and biological properties.

Penicillium sp. FO-125, a soil isolate, was found to produce a new antifungal antibiotic complex named atpenin. Three components A4, A5 and B were isolated from the fermentation broth of the producing strain by solvent extraction, silica gel column chromatography and HPLC. The molecular formula of atpenins A4, A5 and B were determined to be C15H22NO5Cl, C15H21NO5Cl2 and C15H23NO5, respectively, on the basis of high resolution electron impact mass spectrometry and elemental analysis. They are active against filamentous fungi, especially, Trichophyton sp.

Plasticizers as contaminants in commercial ethanol.

A batch of 95% ethanol caused unusually strong disordering of biomembranes, which could be detected either by fluorescence anisotropy in synaptosomal membranes or by electron paramagnetic resonance spectroscopy in erythrocyte membranes. The contaminated batches of ethanol were visibly fluorescent when evaporated on filter paper. The adulterants were separated by capillary gas chromatography and the ubiquitous pollutant dioctylphthalate was identified by its low resolution electron impact mass spectrum. The remaining peaks, which were not recognized by any of the available mass spectral libraries, were identified by high resolution electron impact and chemical ionization mass spectrometry and low resolution tandem mass spectrometry using fast atom bombardment ionization; they were triethylene glycol esters and aryl phosphates. All the contaminants are industrial plasticizers. Distillation resulted in loss of the strong disordering properties of the alcohol.

Structure of fredericamycin A, an antitumor antibiotic of a novel skeletal type. Spectroscopic and mass spectral characterization.

IR, UV-visible spectroscopy, circular dichroism, 1H and 13C NMR studies, high resolution electron impact, field desorption, and fast atom bombardment mass spectral studies are reported for fredericamycin A (NSC-305263), a novel antitumor antibiotic of acid-base indicator type produced by Streptomyces griseus (FCRC-48). The spectral data are correlated with the structure obtained by X-ray crystallography as (E,E)-6',7'-dihydro-4,9,9'-trihydroxy-6-methoxy-3'-(1,3-pentadienyl++ +)-spiro- [2H-benz[f]indene-2,8'-[8H]-cyclopent-[g]-isoquinoline]-1,1', 3,5,8(2'H)-pentone. The novel spiro ring antibiotic exhibits unusual 1H and 13C NMR spectroscopic and chemical behavior, not previously observed in other antibiotic structures.

Studies on WF-3681, a novel aldose reductase inhibitor. I. Taxonomy, fermentation, isolation and characterization.

WF-3681 was isolated from a cultured filtrate of Chaetomella raphigera as a novel inhibitor of aldose reductase. It was extracted with ethyl acetate and then purified with silica gel chromatography. Its molecular formula was determined to be C13H12O5 by elemental analysis and high resolution electron impact mass spectrometry. IC50 of WF-3681 was 2.5 X 10(-7) M for partially purified aldose reductase of rabbit lens.

1-Thiocarbamoyl-2-imidazolidinone, a metabolite of niridazole in Schistosoma mansoni

Niridazole, a nitro heterocyclic antischistosomal drug, is extensively metabolized to unknown metabolites by Schistosoma mansoni. We report that 1-thiocarbamoyl-2-imidazolidinone was isolated by high pressure liquid chromatography and identified by high resolution electron impact mass spectroscopy as a niridazole metabolite in schistosomes. After a 20-h in vitro incubation in 30 ml of medium containing 10 μg ml −1 [ 14C]niridazole (5.2 Ci mol −1), 100 S. mansoni worm pairs contained approximately 275 ng of 1-thiocarbamoyl-2-imidazolidinone. This amount represented 4% of the total metabolized fraction of niridazole in the parasite. Incubation of schistosomes with 1-thiocarbamoyl-2-[2 14C]imidazolidinone (2.7 Ci mol −1) indicated that this metabolite was not taken up. However, schistosomes released an average of 44 ng ml −1 or 1% of the total 1-thiocarbamoyl-2-imidazolidinone found in the worm back into 1 ml of medium during incubation. No host oxidative metabolites of niridazole were found in the parasites.

Application of mass spectrometry in the regulatory analysis of pesticides and industrial chemicals in food and feed commodities.

During regulatory analysis of pesticides and industrial chemicals, compounds are frequently encountered which cannot be readily identified by gas chromatography alone on two or more stationary phases. Such incurred unknown analytical responses are examined by gas chromatography mass spectrometry, particularly if they have been shown to contain P, S, N or halogen via specific gas chromatography detectors. Seven case histories are presented to illustrate the analytical approach adopted to structurally elucidate such compounds at the ppm level. These examples demonstrate the potential complementary combination provided by low resolution electron impact and chemical ionization mass spectrometry in structural determinations.