Structure Determination of Glucosylβ1-N-(ω-O-Linoleoyl)-Acylsphingosines of Human Epidermis

Human epidermis gave two glycolipid bands that migrated faster than glucosylceramide and two bands that migrated like glucosylceramide and galactosylceramide, respectively, on TLC. The two faster migrating glycolipids (GL-I and GL-II), which exhibited alkalilability, were purified by conventional DEAE and silica gel column chromatographies, and further by HPLC on a silica gel column. Structure determination of the two components, named GL-I3 and GL-II3, which were finally purified from GL-I and GL-II, respectively, by HPLC on a reversed phase column, was performed by means of 1H-NMR spectroscopy, fast atom bombardment mass spectrometry, and component analysis involving GLC-mass spectrometry. GL-I3 was determined to be a mixture of glucosyl beta 1-N-(omega-O-linoleoyl)-triacontanoyl- and -dotriacontamonoenoyl-eicosasphingenine, and one of the two components of GL-II3 was determined to be glucosyl beta 1-N-(omega-O-linoleoyl)triacontanoyl-trihydroxyeicosasphingenin e. GL-I3 and GL-II3 were the major components of GL-I and GL-II, respectively, and both the latter contained additional four components, which were heterogeneous as to the ceramide portion. This paper reports the structures of acylglucosylceramides isolated from human epidermis together with 1H-NMR spectra and mass spectra demonstrating their molecular weights. The structure of molecular species containing trihydroxysphingosine having a double bond is novel.