Analysis of alcohols, as dimethylglycine esters, by electrospray ionization tandem mass spectrometry

Johnson, David W.

doi:10.1002/jms.125

Cited by 25 publications

(22 citation statements)

References 29 publications

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“…Two suggested structures of C 8 fragments are shown in ta- applied to improve polarity (such as derivatization to cholesterol-3-sulphate by a trioxidepyridine complex [5], dimethylglycine ester derivatization [22] or the substitution of the ESI interface for the atmospheric pressure chemical ionization head [23]) was not necessary. Our experiments produced similar tandem mass spectrums to those obtained by Johnson [24] using mono-(dimethylaminoethyl) succinyl derivatization of the steroid.…”

Section: Cholesterol Sulphatesupporting

confidence: 54%

Mass Spectrometric Examinations of Stratum corneum Lipid Models Exposed to Ultraviolet Irradiation

Trommer

Plätzer

Wolf

et al. 2003

Skin Pharmacol Physiol

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Lipid model systems consisting of the major components of the stratum corneum intercellular lipid matrix were studied to investigate the ultraviolet-radiation-mediated damage of these biomolecules. Pure lipids and liposomes were irradiated using a lamp emitting a solar radiation spectrum. The influences of the irradiation and the effects of added iron ions were studied by electrospray ionization mass spectrometry (MS) with an ion trap analyser. Exact mass measurements were carried out using a time-of-flight mass spectrometer. Only linolenic acid and cholesterol were found to be subject to oxidative changes caused by UV irradiation whereas the other lipids examined (dipalmitoylphosphatidylcholine, ceramide III and cholesterol sulphate) were stable to oxidative stress. Several lipid adducts were observed upon analysis of the liposomes. The composition of these adducts was identified by MS/MS experiments.

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Section: Cholesterol Sulphatesupporting

confidence: 54%

Mass Spectrometric Examinations of Stratum corneum Lipid Models Exposed to Ultraviolet Irradiation

Trommer

Plätzer

Wolf

et al. 2003

Skin Pharmacol Physiol

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“…36 Since it is difficult to completely exclude moisture from lipid extracts of biological samples, it is more convenient to employ water-stable reagents. A mixture of DMG, EDC, and DMAP as derivatizing reagents was used in this study.…”

Section: Preparation Of Dimethylglycine Esters Of Oxysterolsmentioning

confidence: 99%

Characterization of oxysterols by electrospray ionization tandem mass spectrometry after one‐step derivatization with dimethylglycine

Jiang

Ory

Han

2006

Rapid Comm Mass Spectrometry

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We report a novel approach to derivatize the primary, secondary, and tertiary hydroxy group(s) of oxysterols with N,N-dimethylglycine (DMG) in the presence of both 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 4-(N,N-dimethylamino)pyridine to yield their corresponding mono-or di-DMG esters. Eight oxysterols including 7-oxocholesterol, 5α,6α-and 5β,6β-epoxycholesterols, as well as 7α-, 7β-, 24(S)-, 25-, and 27-hydroxycholesterols, were studied. Electrospray ionization tandem mass spectrometric characterization of these singly or doubly protonated derivatives demonstrates the presence of an informative fragmentation pattern for each oxysterol derivative. Potential dissociation pathways for the production of these unique fragmentation patterns are proposed and discussed. Collectively, these informative and unique fragmentation patterns allow rapid and direct discrimination of the identities of 7α-, 7β-, 24(S)-, 25-, and 27-hydroxycholesterol isomers, as well as 5α,6α-and 5β,6β-epoxycholesterol isomers, thereby potentially providing a foundation for quantitative analysis of oxysterols in biological samples in combination with a chromatographic separation.Oxysterols are 27-carbon oxidation derivatives of cholesterol, which play multiple important roles in biological processes including mediation of inflammatory events in the development of atherosclerotic lesions, 1 regulation of cholesterol homeostasis, 2 maintenance of neuronal functions, 3 and activation of liver X receptors. 4 Oxysterols can be produced either by enzymatic or by non-enzymatic oxidation (known as autoxidation) and may also be obtained from dietary sources. 5-7The most common oxysterols are those derived by formation of hydroxyl, oxo, and epoxy moieties. 7α-, 24(S)-, and 27-Hydroxycholesterols are the major products generated by cholesterol hydroxylases. 8 7α-and 7β-Hydroxycholesterols are also produced through autoxidation of cholesterol. Whether 7β-hydroxycholesterol (which accounts for less than 10% of 7-hydroxycholesterol) is also the product of an enzymatic action is not well defined. Newly developed methods based on atmospheric pressure ionization techniques (e.g., electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI)) alleviate the thermal degradation problems encountered with GC/MS. LC/APCI-MS has been used to determine cholesterol oxidation products without derivatization. 23-27 However, unequivocal identification by APCI-MS/MS was impossible because the energy in collision-induced dissociation (CID) used in those studies was not sufficient to break the stable carbon-carbon bonds in sterols. 27 The most abundant ions are those resulting from non-specific fragmentation (e.g., loss of water). Although ESI-MS is in general more sensitive than APCI-MS for compounds that carry polar groups and has recently been used for analyses of anabolic steroids, 28 oxysterols are not readily detectable by ESI-MS due to their relatively low ionization efficiencies.Therefore, to resolve this problem, one option is to d...

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“…1 Recently, DMG esters were proposed as new derivatives for the rapid, sensitive and selective analysis of primary and secondary alcohols in complex mixtures, by electronspray ionization tandem mass spectrometry (ESI-MS-MS). 2 These esters have also been used as first reagents in the synthesis of lipids, including choline. 3,4 The N,N-dimethylglycine methyl ester (DMG-Me) is the canonical analogue of the permanent zwitterionic species betaine (N,N,N-trimethylglycine), whose biochemical relevance is also well known.…”

mentioning

confidence: 99%

Low temperature FT-IR and molecular orbital study of N,N-dimethylglycine methyl ester: Proof for different ground conformational states in gas phase and in condensed media

Gómez‐Zavaglia

Fausto

2003

Phys. Chem. Chem. Phys.

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Analysis of alcohols, as dimethylglycine esters, by electrospray ionization tandem mass spectrometry

Cited by 25 publications

References 29 publications

Mass Spectrometric Examinations of Stratum corneum Lipid Models Exposed to Ultraviolet Irradiation

Mass Spectrometric Examinations of Stratum corneum Lipid Models Exposed to Ultraviolet Irradiation

Characterization of oxysterols by electrospray ionization tandem mass spectrometry after one‐step derivatization with dimethylglycine

Low temperature FT-IR and molecular orbital study of N,N-dimethylglycine methyl ester: Proof for different ground conformational states in gas phase and in condensed media

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