Abstract
Sphingolipids are ubiquitous in all eukaryotic organisms. Various physiological functions of dietary sphingolipids, such as preventing colon cancer and improving the skin barrier function, have been recently reported. One of the common sphingolipids used as a foodstuff is glucosylceramide from plant sources, which is composed of sphingoid bases distinct from those of mammals. However, the fate of dietary sphingolipids derived from plants is still not understood. In this study, we investigated the absorption of maize glucosylceramide in the rat intestine using a lipid absorption assay of lymph from the thoracic duct. The free and complex forms of trans-4,cis-8-sphingadienine, the predominant sphingoid base of maize glucosylceramide, were found in the lymph after administration of maize glucosylceramide. This plant type of sphingoid base was detected in the ceramide fraction and N-palmitoyl-4,8-sphingadienine (C16:0-d18:2) and N-tricosanoyl-4,8-sphingadienine (C23:0-d18:2) were identified by LC-MS/MS. The cumulative recovery of 4t,8c-sphingadienine in the lymph was very low. These results indicate that dietary glucosylceramide originating from higher plants is slightly absorbed in the intestine and is incorporated into ceramide structures in the intestinal cells. However, it appears that the intact form of sphingoid bases is not reutilized well in the tissues.
Highlights
Sphingolipids are ubiquitous in all eukaryotic organisms
We investigated the absorption in the rat intestine of dietary glucosylceramide derived from maize compared with glucosyl-N-palmitoylsphingosine
We demonstrate that the intact form of 4,8-sphingadienine, Fig. 7
Summary
Sphingolipids are ubiquitous in all eukaryotic organisms. Various physiological functions of dietary sphingolipids, such as preventing colon cancer and improving the skin barrier function, have been recently reported. The free and complex forms of trans-4,cis-8-sphingadienine, the predominant sphingoid base of maize glucosylceramide, were found in the lymph after administration of maize glucosylceramide. The cumulative recovery of 4t,8c-sphingadienine in the lymph was very low These results indicate that dietary glucosylceramide originating from higher plants is slightly absorbed in the intestine and is incorporated into ceramide structures in the intestinal cells. It appears that the intact form of sphingoid bases is not reutilized well in the tissues.—Sugawara, T., T. Dietary sphingolipids can be hydrolyzed to their components, such as sphingoid bases, fatty acids, and the polar head group, by intestinal enzymes and are taken up by mucosal cells [24, 25].
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