The unusual fragmentation of long-chain feruloyl esters under negative ion electrospray conditions

2019 ◽  
Vol 54 (6) ◽  
pp. 549-556 ◽  
Author(s):  
Jürgen Schmidt ◽  
Dietmar Kuck ◽  
Katrin Franke ◽  
Haider Sultani ◽  
Annegret Laub ◽  
...  
Keyword(s):  
Negative Ion ◽  
Unusual Fragmentation ◽  
Long Chain

Apolipoprotein A-I mimetic peptide inhibits atherosclerosis by altering plasma metabolites in hypercholesterolemia

2012 ◽  
Vol 303 (6) ◽  
pp. E683-E694 ◽  
Author(s):  
Zhi-Jun Ou ◽  
Li Li ◽  
Xiao-Long Liao ◽  
Yi-Ming Wang ◽  
Xiao-Xia Hu ◽  
...  
Keyword(s):  
Metabolic Profiling ◽  
Atherosclerotic Lesion ◽  
Time Dependent ◽  
Negative Ion ◽  
Plasma Metabolites ◽  
Dependent Manner ◽  
Mimetic Peptide ◽  
Apolipoprotein A ◽  
Long Chain ◽  
Potential Biomarkers

An apolipoprotein A-I mimetic peptide, D-4F, has been shown to improve vasodilation and inhibit atherosclerosis in hypercholesterolemic low-density lipoprotein receptor-null (LDLr−/−) mice. To study the metabolic variations of D-4F ininhibiting atherosclerosis, metabonomics, a novel system biological strategy to investigate the pathogenesis, was developed. Female LDLr−/− mice were fed a Western diet and injected with or without D-4F intraperitoneally. Atherosclerotic lesion formation was measured, whereas plasma metabolic profiling was obtained on the basis of ultra-high-performance liquid chromatography in tandem with time-of-flight mass spectrometry operating in both positive and negative ion modes. Data were processed by multivariate statistical analysis to graphically demonstrate metabolic changes. The partial least-squares discriminate analysis model was validated with cross-validation and permutation tests to ensure the model's reliability. D-4F significantly inhibited the formation of atherosclerosis in a time-dependent manner. The metabolic profiling was altered dramatically in hypercholesterolemic LDLr−/− mice, and a significant metabolic profiling change in response to D-4F treatment was observed in both positive and negative ion modes. Thirty-six significantly changed metabolites were identified as potential biomarkers. A series of phospholipid metabolites, including lysophosphatidylcholine (LysoPC), lysophosphatidylethanolamine (LysoPE), phosphatidylcholine (PC), phatidylethanolamine (PE), sphingomyelin (SM), and diacylglycerol (DG), particularly the long-chain LysoPC, was elevated dramatically in hypercholesterolemic LDLr−/− mice but reduced by D-4F in a time-dependent manner. Quantitative analysis of LysoPC, LysoPE, PC, and DG using HPLC was chosen to validate the variation of these potential biomarkers, and the results were consistent with the metabonomics findings. Our findings demonstrated that D-4F may inhibit atherosclerosis by regulating phospholipid metabolites specifically by decreasing plasma long-chain LysoPC.

Natural Waxes Investigated by Soft Ionization Mass Spectrometry

1987 ◽  
Vol 42 (3) ◽  
pp. 178-190 ◽  
Author(s):  
H .-R . Schulten ◽  
K. E. Murray ◽  
N. Simmleit
Keyword(s):  
Mass Spectrometry ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Negative Ion ◽  
High Mass ◽  
Forest Damage ◽  
Field Ionization ◽  
Ionization Mass ◽  
Field Desorption ◽  
Long Chain

Field ionization (FI) and field desorption (FD) mass spectra of 35 aliphatic long-chain and branched long-chain compounds, representing the major six classes of constituents of natural waxes, are examined. In the FI mode the molecular ions are usually formed at comparatively low levels, while in FD such species are almost exclusively generated. In addition, some fast atom bombardment mass spectra, in the positive and negative ion mode, of selected lipids are recorded for comparison. In general, field ionization and field desorption techniques are found to be superior for mass spectrometric studies of low-polarity compounds. Examination of several natural waxes, such as Jojoba wax, preen gland wax of goose, beeswax and epicuticular wax of Norway spruce, shows that field desorption mass spectrometry has a most promising role in the characterization of wax components. The intense molecular ions allow the identification of the constituents of complex lipid mixtures without the need for derivatization. Thus, for the first time, the carbon number distribution, especially of the high-mass wax con­stituents can be established for the natural waxes investigated. For identification of high-mass wax constituents the present results suggest that field desorption mass spectra could be best employed in conjunction with class and individual separation of constituents by chromatographic proce­dures. The analysis of natural waxes is nowadays of major concern because of its importance in the problem of forest damage.

Electron impact studies. XCVI. Negative ion mass spectra of naturally occurring compounds. Nitrophenyl esters derived from long-chain acids andalcohols

1975 ◽  
Vol 28 (5) ◽  
pp. 1011 ◽  
Author(s):  
JH Bowie ◽  
BJ Stapleton
Keyword(s):  
Electron Impact ◽  
Analytical Method ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Negative Ion ◽  
Impact Studies ◽  
Naturally Occurring ◽  
Molecular Anions ◽  
Positive Ion ◽  
Long Chain

The positive ion mass spectra of long-chain alcohols and acids are either devoid of molecular ions or contain such species in low abundance. The negative ion spectra of p-nitrophenyl esters of these compounds exhibit pronounced molecular anions, showing the technique to be a useful analytical method for these classes of compounds.

Positively Charged Latex

1941 ◽  
Vol 14 (3) ◽  
pp. 656-658
Author(s):  
B. V. Coplan ◽  
S. S. Rogers ◽  
L. A. Hansen
Keyword(s):  
Isoelectric Point ◽  
Rubber Particle ◽  
Negative Ion ◽  
Basic Solution ◽  
Colloidal Systems ◽  
Net Charge ◽  
Basic Solutions ◽  
Positive Ion ◽  
Positively Charged ◽  
Long Chain

Abstract Latex, like many other colloidal systems, owes its stability to a large extent to the electrical charge carried by each particle in suspension. One possible explanation of how the particles become charged is that the protein adsorbed on the rubber hydrocarbon is capable of ionizing to a slight extent, both as an acid and as a base, much in the same manner as do amino acids. In a highly basic solution the rubber particle acquires a negative charge; whereas in an acid solution the charge is positive. At some stage between strongly acid and strongly basic solutions, the ionization of the adsorbed protein layer would be as much acidic as basic, and the particle would have no net charge. This is known as the isoelectric point, and has been found to be at a pH of 4.2. At or near the isoelectric point, the latex is very unstable, and coagulates rapidly. The charge carried by the particle may, of course, be due also to adsorption of ions from solution. The latex particles are normally negatively charged, but the sign of the charge can be reversed by the addition of acid, by the presence of polyvalent cations, and more recently it has been shown that cationic soaps may reverse the charge. In a cationic soap the positive ion is a long chain, and the negative ion is a halide, sulfate, etc. The hydrophilic group attached to the long chain of carbon atoms is a quaternary ammonium, sulfonium, or phosphonium group. The authors felt that, because positively charged latex seems to have some commercial possibilities, it would be of interest to attempt to prepare latex suspensions of reversed charge of higher concentrations than those used by Blow, which were apparently around 5 per cent.

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