Separation and characterization of hematosides with different sialic acids and ceramides from rat small intestine. Different composition of epithelial cells versus non-epithelial tissue and of duodenum versus jejunum-ileum.

The hematosides (sialyl-lactosylceramides) of rat small intestine were separated as their acetylated derivatives. The isolated fractions were characterized by mass spectrometry and degradative methods, and the two major fractions also by NMR spectroscopy. From these results hematosides with different sialic acid and ceramide type could be assigned to thin-layer chromatographic bands. This allowed a structural interpretation of the chromatographic patterns observed for different parts of the small intestine. Thus, epithelial cells of ileum contained only hematoside with N-glycoloylneuraminic acid. Duodenum lacked this compound and instead the epithelial cells contained hematoside with N-acetylneuraminic acid. In non-epithelial tissue or both duodenum and jejunum-ileum the major hematoside had N-acetyl-neuraminic acid. The hematosides of epithelial cells had ceramide containing 18 : 0 trihydroxy base combined with 16, 20, 22, 24 : 0, and 24 : 1 hydroxy fatty acids (major part) or non-hydroxy fatty acids. In the non-epithelial hematosides the ceramide consisted of 18 : 1 dihydroxy base combined with 16, 18, 20, 22, 24 : 0, and 24 : 1 non-hydroxy fatty acids.