Structural Characterization of Neutral Glycosphingolipids, Mono-, Di- and Triglycosylceramides, from the Marine Annelid, Pseudopotamilla occelata

Abstract

Neutral glycosphingolipids were extracted from the marine annelid, Pseudopotamilla occelata and separated into five fractions (CMS1, CMS2, CDS1, CDS2 and CTS) by their modes of column chromatography, ion exchange Sephadex (QAE-Sephadex), magnesium silicate (Florisil) and silicic acid (Iatrobeads). The chemical structures of the glycolipids in each fraction were determined by compositional analysis, methylation analysis, exoglycosidase cleavage, gas-liquid chromatography, gas chromatograph-mass spectrometry and matrix-assisted laser desorption ionization time-of-flight mass spectrometry, by which sugar, sphingoid and fatty acid compositions were clarified. Based on the results, their structures were proposed as Glcβ1-1ceramide and Galβ1-1ceramide (1.00 : 0.16) for CMS1, Glcβ 1-1ceramide for CMS2, Galα 1-4Galβ 1-1ceramide for CDS1, Ga1β 1-4G1cβ1-1ceramide for CDS2, and GlcNAcβ 1-3Galβ 1-4Glcβ 1-1ceramide for CTS. In the aliphatic moiety, the sphingoid component of all glycolipids was found to consist solely of octadeca-4-sphingenine. The fatty acid components of CMS1 and CDS1, or CDS2 and CTS were quite similar, consisting mainly of 16 : 0-, 17 : 0- and 18 : 0-acids, or 20 : 1- and 22 : 1-acids. The fatty acid components of CMS2 differed markedly from those of other glycolipids, and consisted primarily of 2-hydroxy 16 : 0-, 17 : 0- and 18 : 0-acids.Thin-layer chromatography and the results of sugar analysis indicated the presence of new glycolipids, penta- and hexaglycosylceramides possessing fucose, xylose and 2- (ο-methyl) galactose as additional sugar components. No glycosphingolipid component corresponding to tetraglycosylceramide could be detected by the present analyses.