Stereochemical and structural assignment to benzomorphans by mass spectrometry

1973 ◽  
Vol 25 (11) ◽  
pp. 895-899 ◽  
Author(s):  
D. P. VAUGHAN ◽  
A. H. BECKETT
Keyword(s):  
Mass Spectrometry ◽  
Structural Assignment

scholarly journals Structure elucidation of colibactin and its DNA cross-links

Science ◽  
2019 ◽  
Vol 365 (6457) ◽  
pp. eaax2685 ◽  
Author(s):  
Mengzhao Xue ◽  
Chung Sub Kim ◽  
Alan R. Healy ◽  
Kevin M. Wernke ◽  
Zhixun Wang ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Mass Spectrometry ◽  
Cell Biology ◽  
Structure Elucidation ◽  
Isotope Labeling ◽  
Tandem Mass ◽  
Physiological Effects ◽  
Human Gut ◽  
Structural Assignment ◽  
Cross Links

Colibactin is a complex secondary metabolite produced by some genotoxic gut Escherichia coli strains. The presence of colibactin-producing bacteria correlates with the frequency and severity of colorectal cancer in humans. However, because colibactin has not been isolated or structurally characterized, studying the physiological effects of colibactin-producing bacteria in the human gut has been difficult. We used a combination of genetics, isotope labeling, tandem mass spectrometry, and chemical synthesis to deduce the structure of colibactin. Our structural assignment accounts for all known biosynthetic and cell biology data and suggests roles for the final unaccounted enzymes in the colibactin gene cluster.

Tetranitroquinodimethane (Tnq)—Electron-Deficient Prototype for a New Series of Organic Solid State Materials

1989 ◽  
Vol 173 ◽  
Author(s):  
David J. Vanderah ◽  
A. T. Nielsen ◽  
R. A. Hollins ◽  
Chris Baum
Keyword(s):  
Mass Spectrometry ◽  
Solid State ◽  
Title Compound ◽  
Radical Anion ◽  
H Nmr ◽  
Structural Assignment ◽  
Spectral Evidence ◽  
Vacuum Pyrolysis ◽  
Organic Solid ◽  
Solid State Materials

ABSTRACTRecently we have synthesized several new aryl compounds substituted with two or more trinitromethyl groups. Vacuum pyrolysis of one of these—±,±,±,±’,±’,±’-hexanitro-p-xylene (p-HNX)—gave the title compound via 1,6-elimination of N2O4. Structural assignment of TNQ is based on spectral evidence (UV, 1H NMR and mass spectrometry) and conversion to the known l,4-bis(bromodinitromethyl)benzene. Evidence for the formation of the TNQ radical anion has been obtained.

Photoproducts of 7-Hydroxycoumarins in Aqueous Solution

2012 ◽  
Vol 65 (10) ◽  
pp. 1451 ◽  
Author(s):  
Gerald J. Smith ◽  
Roderick J. Weston ◽  
Ying Tang ◽  
Yinrong Lu ◽  
Jolon M. Dyer
Keyword(s):  
Mass Spectrometry ◽  
Aqueous Solution ◽  
Excited State ◽  
Mass Spectrum ◽  
Solid State ◽  
Aqueous Solutions ◽  
Fluorescence Spectra ◽  
Major Product ◽  
Structural Assignment ◽  
Esi Mass Spectrometry

Near-UV irradiation of aqueous solutions of 7-hydroxy-6-methoxycoumarin (scopoletin) and 6,7-dihydroxycoumarin (esculetin) resulted in the formation of dimers. Substantially greater amounts of the 7-hydroxy-6-methoxycoumarin photodimer were produced compared with that of 6,7-dihydroxycoumarin. Fluorescence spectra indicated that the initial photolytic reaction involves the excited state of the phenolate form of the monomeric coumarin. The electro-spray ionization (ESI) mass spectrum suggested that the major product (with a sodiated quasimolecular ion at m/z 405) from the photolysis of scopoletin in water had formed by oxidative dimerisation and possibly had a 3,3′-bond. A second dimer (with a sodiated quasimolecular ion at m/z 407) was probably a 2 + 2 cyclodimer. This work concluded that photolysis of coumarins in water results in oxidative dimerisation whereas photolysis in the solid state or in organic solvents results in cyclodimerisation. Minor monomeric photoproducts were a dihydroxy-6-methoxycoumarin from 7-hydroxy-6-methoxycoumarin and a trihydroxycoumarin from 6,7-dihydroxycoumarin. During ESI-mass spectrometry (ESI-MS), sodiated quasimolecular ions of the photodimer formed more readily than protonated quasimolecular ions and the sodiated ions did not fragment readily. Protonated quasimolecular ions of the monomeric coumarins formed more readily than their sodiated counterparts and the protonated ions fragmented to create daughter ion spectra that were useful for chemical structural assignment.

How SIMS microscopy can be used in medicine

1992 ◽  
Vol 50 (2) ◽  
pp. 1602-1603
Author(s):  
Philippe Fragu
Keyword(s):  
Mass Spectrometry ◽  
Biomedical Applications ◽  
Secondary Ion Mass Spectrometry ◽  
Chemical Elements ◽  
Biological Applications ◽  
The Past ◽  
Potential Source ◽  
Secondary Ion ◽  
Chemical Integrity ◽  
Scientific Endeavour

The identification, localization and quantification of intracellular chemical elements is an area of scientific endeavour which has not ceased to develop over the past 30 years. Secondary Ion Mass Spectrometry (SIMS) microscopy is widely used for elemental localization problems in geochemistry, metallurgy and electronics. Although the first commercial instruments were available in 1968, biological applications have been gradual as investigators have systematically examined the potential source of artefacts inherent in the method and sought to develop strategies for the analysis of soft biological material with a lateral resolution equivalent to that of the light microscope. In 1992, the prospects offered by this technique are even more encouraging as prototypes of new ion probes appear capable of achieving the ultimate goal, namely the quantitative analysis of micron and submicron regions. The purpose of this review is to underline the requirements for biomedical applications of SIMS microscopy.Sample preparation methodology should preserve both the structural and the chemical integrity of the tissue.

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