Cytolipin R and Its Possible Precursor Ceramide Trisaccharide from Metastatic Rat Mammary Tumor

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Ceramide mono-, di-, and trihexoside, two globosides, and hematoside were isolated from metastatic rat mammary tumor (MRMT-1) by column chromatography on silicic acid and preparative thin-layer chromatography. Each glycolipid was analyzed for fatty acids, long chain bases, and sugars. A combination of periodate oxidation, specific enzymatic hydrolysis, permethylation, and gas chromatographic studies of the sugar moieties established the arrangement of sugars, their anomeric configurations, and positions of their anomeric linkages in the lipids. The main glycolipids were two globosides having structure identical with cytolipin R; N-acetylgalactosaminyl(β1→3) galactosyl (α1→3) galactosyl (β1→4) glucosyl-ceramide. The only structural differences were in their component fatty acid composition. The structure of ceramide trisaccharide was galactosyl (α1→3) galactosyl (β1→4) glucosyl-ceramide, which is assumed to be a possible precursor of cytolipin R. The hematoside from this tumor was N-acetylneuraminyl-lactosyl-ceramide.