Investigating the degradation of the sympathomimetic drug phenylephrine by electrospray ionisation-mass spectrometry.

The frequently used sympathomimetic drug phenylephrine has been studied by electrospray ionisation-mass spectrometry. The stability of the adrenoceptor agonist was examined by investigations of the pharmaceutically used salts phenylephrine hydrochloride and phenylephrine bitartrate. Photostability has been studied by use of an irradiation equipment emitting a solar radiation spectrum.

Normal phase liquid chromatography coupled to quadrupole time of flight atmospheric pressure chemical ionization mass spectrometry for separation, detection and mass spectrometric profiling of neutral sphingolipids and cholesterol.

Many lipidomic approaches focus on investigating aspects of sphingolipid metabolism. Special emphasis is put on neutral sphingolipids and cholesterol and their interaction. Such an interest is attributed to the fact that those lipids are altered in a series of serious disorders including various sphingolipidoses.

Screening for nutritive peptides that modify cholesterol 7alpha-hydroxylase expression.

Bioactive peptides with a variety of effects have been described from several nutritive proteins. They exhibit antimicrobial, blood-pressure lowering, antithrombotic, immunomodulatory, and cholesterol-modulating effects. In this study, we have examined whether peptides derived from food proteins might influence bile acid synthesis.

Peptic digestion of beta-casein. Time course and fate of possible bioactive peptides.

Numerous peptides obtained by enzymatic digestion of food proteins have been reported to exhibit biological activities. In this study, the focus was placed on peptides of beta-casein from bovine milk after a gastro-analogous in vitro digestion with pepsin, a protease with broad specificity. In order to study the time course of the digestion, the process was stopped after specific times and the samples were subjected to HPLC separation followed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) and nanoelectrospray (nanoESI) quadrupole time-of-flight (qTOF) mass spectrometry.

Separation and mass spectrometric characterization of covalently bound skin ceramides using LC/APCI-MS and Nano-ESI-MS/MS.

Ceramides covalently bound to keratinocytes are essential for the barrier function of the skin, which can be disturbed in diseases, such as psoriasis and atopic dermatitis. These ceramides of the classes omega-hydroxyacyl-sphingosine and omega-hydroxyacyl-6-hydroxysphingosine contain an omega-hydroxy fatty acid. For their separation and identification, a new analytical approach based on normal phase liquid chromatography coupled to atmospheric pressure chemical ionization mass spectrometry and tandem nano-electrospray mass spectrometry, respectively, is presented here.

Targeted ablation of Arnt in mouse epidermis results in profound defects in desquamation and epidermal barrier function.

The molecular mechanisms of skin adaptation to the environmental stress are poorly understood. The aryl hydrocarbon receptor nuclear translocator (Arnt) lies at the intersection of several crucial adaptive pathways. Nevertheless, its role in adaptation of the skin to environmental stress has just begun to be unraveled.

Towards a molecular characterization of pharmaceutical excipients: mass spectrometric studies of ethoxylated surfactants.

The in-depth characterization of excipients is a prerequisite for their safe application in pharmaceutical products. In case of surfactants, this task can be a challenge, since many industrial products are mixtures of variable composition. In this work, mass spectrometric methods are applied to characterize some ethoxylated surfactants that are widely used by the pharmaceutical industry.

Induction of a hardening phenomenon by repeated application of SLS: analysis of lipid changes in the stratum corneum.

Adaptation of the skin to repeated influence of exogenous irritants is called the hardening phenomenon. We investigated the stratum corneum lipid composition before and after induction of a hardening phenomenon. Irritant contact dermatitis was induced in 23 non-atopic volunteers by repeated occlusive application of 0.

Profiling of human stratum corneum ceramides by means of normal phase LC/APCI-MS.

The ceramides of the stratum corneum are critical to maintaining the epidermal barrier function of the skin. A number of skin diseases and disorders are known to be related to impairments of the ceramide pattern. Therefore, obtaining mass spectrometric profiles of the nine ceramide classes known to exist aids our understanding of the underlying molecular mechanisms, which should eventually lead to new diagnostic opportunities: for example, the mass spectrometric profiles of patients suffering from serious skin diseases such as atopic dermatitis and psoriasis can be compared to those of healthy controls.

Analysis of benzylisoquinoline-type alkaloids by electrospray tandem mass spectrometry and atmospheric pressure photoionization.

Benzylisoquinoline alkaloids found in the Papaveraceae family play a major role in pharmaceutical biology. This is the first systematic study dealing with electrospray tandem mass spectrometry (ESI-MS/MS) of all benzylisoquinolines found as biogenetic precursors of morphinan alkaloids. Tandem mass spectral data are presented for norlaudanosoline, laudanosoline, 4'-O-methyl-norlaudanosoline, 6-O-methyl-norlaudanosoline, norcoclaurine, coclaurine, N-methylcoclaurine, N-methyl-3'-hydroxycoclaurine, N-methyl-3'-O-methylcoclaurine, norreticuline and reticuline.

A new LC/APCI-MS method for the determination of cholesterol oxidation products in food.

Cholesterol oxidation products (COPs) can be formed in the body or in animal foods from cholesterol during food processing. A new method for the extraction and quantification of cholesterol, 7-ketocholesterol, cholestane-3beta-5alpha-6beta-triol, 25-hydroxycholesterol, 5,6alpha-epoxycholesterol, and 7beta-hydroxycholesterol by means of reversed-phase LC/atmospheric pressure chemical ionization mass spectrometry is presented. A baseline separation of all COPs was achieved, allowing a separate quantification also for isobaric compounds.

Ceramide profiles of the uninvolved skin in atopic dermatitis and psoriasis are comparable to those of healthy skin.

Ceramides are sphingolipids consisting of sphingoidbases, which are amide-linked to fatty acids. In the stratum corneum, they represent the major constituent of the free extractable intercellular lipids and play a significant role in maintaining and structuring the water permeability barrier of the skin. Using thin layer chromatography, which represents the method of the first choice in analyzing the stratum corneum ceramides, at least seven classes can be distinguished.

Mass spectrometric characterization of peptides derived by peptic cleavage of bovine beta-casein.

This study investigated the digestion of the milk protein beta-casein with pepsin under gastro-analogous conditions. Peptide sequences were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with post-source decay as well as liquid chromatography-tandem mass spectrometry by means of database searching. The new software tool, Mascot Distiller, improved the identification rate remarkably.

LC/ESI-MS analysis of two elastin cross-links, desmosine and isodesmosine, and their radiation-induced degradation products.

In this work, the effect of Fenton reaction on two elastin cross-linked amino acids, desmosine (DES) and isodesmosine (IDE), in the absence or presence of different wavelength radiations generated from artificial sources has been evaluated using LC/ESI-MS. Irradiation as well as incubation of DES or IDE solutions in the presence of Fe(2+) and H(2)O(2) resulted in products with m/z 497.1 and 481.

Examinations of the antioxidative properties of the topically administered drug bufexamac reveal new insights into its mechanism of action.

The effect of bufexamac on UV-irradiation-induced lipid peroxidation was investigated. Linolenic acid was used as a model lipid. Bufexamac was shown to be capable of reducing the amount of lipid peroxidation.

Electrospray tandem mass spectrometric investigations of morphinans.

In this study positive ESI tandem mass spectra of the [M + H]+ ions of morphinan alkaloids obtained using an ion trap MS were compared with those from a triple quadrupole MS. This allows to assess the differences of the tandem-in-time versus the tandem-in-space principle, often hampering the development of ESI MS/MS libraries. Fragmentation pathways and possible fragment ion structures were discussed.

Identification of hyaluronic acid oligosaccharides by direct coupling of capillary electrophoresis with electrospray ion trap mass spectrometry.

A new method for the identification of oligosaccharides obtained by enzymatic digestion of hyaluronic acid (HA) with bacterial hyaluronidase (HA lyase, E.C. 4.

Quantification of hyaluronic acid fragments in pharmaceutical formulations using LC-ESI-MS.

Three different hyaluronic acid fragment preparations (HAF) derived from hyaluronic acid (HA) by hyaluronate lyase digestion have been investigated. The amount of these fragment mixtures in pharmaceutical formulations was determined by liquid chromatography-electrospray tandem mass spectrometry (LC/MS/MS). HAF analysis was performed in less than 8 min using a Nucleosil 100-7 C2 column.

Improved procedure for the separation of major stratum corneum lipids by means of automated multiple development thin-layer chromatography.

The separation of the major stratum corneum lipids, i.e., ceramides, fatty acids, cholesterol and its esters by means of high-performance thin-layer chromatography is hereby presented.