Christoph Huschka

Rapid quantification of capsaicin and dihydrocapsaicin in human skin extracts after dermal administration using HPLC-ESI-MS

An HPLC electrospray mass spectrometric method for the specific and sensitive quantification of Capsaicin [404-86-4] and Dihydrocapsaicin [19408-84-5] in extracts from human skin is presented. A 2 mm RP18 column was used with a mobile phase of methanol/water/acetic acid 90/9/1 at a flow rate of 0.2 mL/min. The reached limit of detection was 500 pg/mL. MS/MS and MS3 experiments were performed using an ion trap mass spectrometer. The fragmentation pattern in the positive mode is explained. The method was applied to study Capsaicin penetration from different pharmaceutical preparations.

Rapid Quantification of Biotin in Human Skin Extracts After Dermal Application Using High-performance Liquid Chromatography–Electrospray Mass Spectrometry

A method for the determination of the vitamin biotin in extracts from different layers of human skin is presented, which has a detection limit of 800 pg ml–1 without further sample preparation. The quantification was performed using an HPLC procedure on a reversed phase column, which takes only 4 min, coupled to a single quadrupole mass spectrometer via an electrospray ionization interface. The detection was performed in the positive selected ion monitoring mode. Additional MS–MS and MSn experiments with biotin using an ion trap mass spectrometer are described.

Further investigations on the role of ascorbic acid in stratum corneum lipid models after UV exposure

This study is the continuation of our research into vitamin C and its possible effects on human skin after topical administration. The effects of ascorbic acid, iron ions and UV irradiation on stratum corneum lipid models were investigated. The lipid models used were: a simple system (linolenic acid dispersion), a complex system (liposomes consisting of dipalmitoylphosphatidylcholine, cholesterol and linolenic acid) and complex systems with additionally incorporated ceramides (types III and IV). The lipid peroxidation was quantified by the thiobarbituric acid assay. A human adult low‐calcium high‐temperature (HaCaT) keratinocytes cell culture was used as a second in‐vitro model. The amount of intracellular peroxides was determined by measuring the fluorescence intensity using the dihydrorhodamine 123 assay. Electron paramagnetic resonance spectroscopy was used to study the influence of ascorbic acid and iron ions on the signal intensity of 5‐doxylstearic acid during UV exposure. Ascorbic acid showed prooxidative properties in the thiobarbituric acid assay whereas cell protection was measured in the HaCaT keratinocytes experiments. Electron paramagnetic resonance investigations revealed different extents of free radical production generated by iron ions, ascorbic acid and UV irradiation. In evaluating the results from this study new aspects of the mechanism of lipid damage caused by these three factors were suggested, transcending the simple redox behaviour of ascorbic acid.

EVALUATION OF THE INFLUENCE OF HYALURONAN AND HYALURONAN FRAGMENTS ON HUMAN KERATINOCYTES DURING UV IRRADIATION

ABSTRACT In response to the attack of reactive oxygen species (ROS) caused by UV irradiation, skin has developed a complex antioxidant defence system. We investigated the influence of hyaluronan (HA) or hyaluronan fragments (HAF) on UV-irradiated human keratinocytes. We studied the vitality of the cells by the determination of the cell number and the DNA synthesis efficiency using BrdU incorporation. The intracellular changes of the ROS content were determined by a dihydrorhodamine 123 test (DHR). Our results indicate that both HA and HAF protect keratinocytes against the consequences of UVA and UVB irradiation. As a result of UV irradiation an increase in the content of intracellular peroxides was observed. In the presence of HA or HAF, a reduction in the content of ROS could be achieved. With rising doses of UVB the number of viable keratinocytes was decreased, while the additional treatment with HA or HAF led to a significant improvement of viability. The present results might be explained by the anti-inflammatory and radical capturing qualities of HA or HAF.