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Two novel type gangliosides CJP2 and CJP3 have been obtained from the feather star Comanthus japonica. On the basis of methylation linkage analysis combined with ammonolysis and other chemical and spectroscopic evidence, the chemical structures of CJP2 and CJP3 were determined to be a a-9-O-Me-NeuGc-(2→3)-inositolphosphoceramide and a a-9-O-Me-NeuGc-(2→11)-a a-9-O-Me-NeuGc-(2→3)-inositolphosphoceramide, respectively. These gangliosides are unique in that they are inositolphosphoceramide derivatives possessing sialic acid; such gangliosides have not previously been identified. The presence of 9-O-methyl-N-glycolyl-neuraminosyl residues is also unique in naturally occurring gangliosides.

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In our continuing research on biologically active sphingolipids from echinoderms, a series of studies on the isolation and structure elucidation of biologically active glycosphingolipids have been performed in our laboratory. [1][2][3][4][5][6] In a study of the sphingolipids of the feather star Comanthus japonica (Nipponumishida in Japanese), we reported the isolation and structure of inositolphosphoceramide 7) and glycosyl inositolphosphoceramide-type gangliosides 8) from the polar lipid fraction of the chloroform/methanol extract of C. japonica. Continuing the preceding studies, the isolation and characterization of sphingolipids from the less polar lipid fraction was conducted. In this paper, we report the isolation and characterization of ceramides and glucocerebrosides from the whole bodies of C. japonica.The less polar lipid fraction, which was obtained from the chloroform/methanol extract of the whole bodies of C. japonica, was subjected to repeated column chromatography to give a ceramide and a cerebroside molecular species, designated as JC and JCer, each showing a single spot on silica gel thin-layer chromatography (TLC).JC exhibited strong hydroxy and amide absorptions in its IR spectrum and a series of quasi-molecular ion peaks due to [MϪH] Ϫ in its negative ion FAB mass spectrum. In its 13 C-NMR spectra (Fig. 1, Table 1), JC revealed the characteristic signals of a sphingosine-type ceramide possessing a non-hydroxylated fatty acid. Therefore, JC is suggested to be the molecular species of the typical type of ceramide. The structure of JC shown in Fig. 1 was characterized by comparison of its 13 C-NMR spectral data with that of known ceramides 9,10) hitherto reported, and by means of the results of methanolysis followed by GC-MS analysis of the methanolysis products, fatty acid methyl ester (FAM) and long-chain base (LCB), as shown in Fig. 1 and the Experimental section.Based on the considerable interest and importance in determining the molecular species composition of sphingolipids, isolation and structure elucidation of ceramide components in the molecular species JC was conducted. JC could be separated by reversed-phase HPLC into ten peaks, and could be recovered to give ten fractions, 1-10. They behaved as pure compounds in HPLC, however, fractions 1, 2, 3, 6, 7 and 8 were regarded as still heterogeneous compounds, respectively, since they afforded plural molecular ion peaks in their negative ion FAB mass specra. Fractions 6 and 8, the major fractions in the heterogeneous fractions, were successively separated by reversed-phase HPLC using another condition into two peaks, respectively, and could be recovered to three fractions, 6a, 8a and 8b, each showing a single molecular ion peak. When the seven fractions, 4, 5, 6a, 8a, 8b, 9 and 10, believed to be pure substances, were methanolyzed and the FAM obtained from each fraction were analyzed by GC-MS, a single FAM was detected from five fractions (4, 5, 8b, 9, 10) and two kinds of FAM were obtained from the other two fractions. Thus, five homoge...