A new 6-hydroxy-4-sphingenine-containing ceramide in human skin

The composition of the constituents (monosaccharides, long-chain bases, and fatty acids) found in an ethanol extract of the human skin could be determined, without time-consuming steps of purification, after acid-catalyzed anhydrous methanolysis, followed by the formation of volatile derivatives with heptafluorobutyric anhydride and gaschromatography/mass-spectrometry analysis. Despite the extreme heterogeneity of such extracts, the electron impact analysis of the constituents allowed qualitative and quantitative determinations of monosaccharides, long-chain bases, fatty acids, and alkyl-glycerols. Throughout the different longchain bases, sphingenines (Sphes), sphinganines, phytosphingosines, and 6-hydroxy-Sphes (6oh-Sphes) can be identified and quantified. Long-chain bases with a chain-length up to 28 carbon atoms can be identified through specific fragmentation patterns in the electron impact mode. Particular attention was drawn to the behavior of compounds of the family of 6oh-Sphes upon acid-catalyzed methanolysis. -Pons, A., P. Timmerman, Y. Leroy, and J-P. Zanetta. GC/MS analysis of human skin constituents as heptafluorobutyrate derivatives with special reference to long-chain bases.

Section: Heterogeneity Of 6oh-sphesmentioning

confidence: 97%

Section: Heterogeneity Of Sphesmentioning

confidence: 99%

See 1 more Smart Citation

Gas-chromatography/mass-spectrometry analysis of human skin constituents as heptafluorobutyrate derivatives with special reference to long-chain bases

Pons

Timmerman

Leroy

et al. 2002

“…This will help us understand the changes in barrier function and lipid organization in diseased and dry skin. In human SC at least eight subclasses of CER are present (20,21). These HCER, often referred to as HCER1 to HCER8, differ from each other in head group architecture and hydrocarbon chain length.…”

mentioning

confidence: 99%

Phase behavior of lipid mixtures based on human ceramides: coexistence of crystalline and liquid phases

Bouwstra

Gooris

Dubbelaar

et al. 2001

150

The lipid regions in the outermost layer of the skin (stratum corneum) form the main barrier for diffusion of substances through the skin. In this layer the main lipid classes are ceramides, cholesterol (CHOL), and FFA. Previous studies revealed a coexistence of two crystalline lamellar phases with periodicities of approximately 13 nm (referred to as long periodicity phase) and 6 nm (short periodicity phase). Additional studies showed that lipid mixtures prepared with isolated pig ceramides (pigCER) mimic lipid phase behavior in stratum corneum closely. Because the molecular structure of pigCER differs in some important aspects from that of human ceramides (HCER), in the present study the phase behavior of mixtures prepared with HCER has been examined. Phase behavior studies of mixtures based on HCER revealed that in CHOL:HCER mixtures the long periodicity phase dominates. In the absence of HCER1 the short periodicity phase is dominant. Addition of FFA promotes the formation of the short periodicity phase and induces a transition from a hexagonal sublattice to an orthorhombic sublattice. Furthermore, the presence of FFA promotes the formation of a liquid phase. Finally, cholesterol sulfate, a minor but important lipid in the stratum corneum, reduces the amount of cholesterol that phase separates in crystalline domains. From these observations it can be concluded that the phase behavior of mixtures prepared from HCER differs in some important aspects from that prepared from pigCER. The most prevalent differences are the following: i ) the addition of FFA promotes the formation of the short periodicity phase; and ii ) liquid lateral packing is obviously present in CHOL:HCER:FFA mixtures. These changes in phase behavior might be due to a larger amount of linoleic acid moiety in HCER mixtures compared with that in pigCER mixtures. -Bouwstra, J. A., G. S. Gooris, F. E. R. Dubbelaar, and M. Ponec. Phase behavior of lipid mixtures based on human ceramides: coexistence of crystalline and liquid phases.

“…6-Hydroxysphingosine is also found in three classes of free ceramides of human skin. The fatty acid moieties of these three classes are: nonhydroxyacids, ␣ -hydroxyacids, or -hydroxyacids having a nonhydroxyacid esterified to the -hydroxyl group (12,13).…”

Section: Structure Of the Corneocyte Lipid Envelopementioning

confidence: 99%

The ω-hydroxyceramides of pig epidermis are attached to corneocytes solely through ω-hydroxyl groups

Stewart

Downing

2001

Self Cite

The cornified outer cells of mammalian epidermis possess a monolayer of -hydroxyceramides that are ester-linked to the exterior of a cross-linked protein envelope. In the present study, conclusive evidence was sought on which of the ceramide hydroxyl groups are involved in the linkage to protein. This was obtained by derivatizing all free hydroxyl groups in isolated solvent-extracted porcine stratum corneum using triisopropylsilyl (TIPS) chloride in pyridine in the presence of silver nitrate. After an 18-h reaction, the tissue was recovered, rinsed, and the derivatized ceramides were then released from protein linkage by hydrolysis with 1M KOH in 95% methanol. This gave a single ceramide product that was shown by nuclear magnetic resonance to contain two triisopropyl groups. Acetylation of the product using acetic anhydride in pyridine resulted in a downfield shift of the NMR signal for the -methylene protons, showing that it was the -hydroxyl that was free in the initial reaction product, and subsequently was acetylated. These results show that all of the -hydroxyceramides of corneocyte lipid envelopes are attached to protein through their -hydroxyl groups. -Stewart, M. E., and D. T. Downing. The -hydroxyceramides of pig epidermis are attached to corneocytes solely through -hydroxyl groups.