Quantification of glycosylinositol phosphoceramide and phytoceramide-1-phosphate in foodstuffs

Recent studies have shown beneficial effects of dietary sphingolipids on our health and beauty, such as prevention of aberrant crypt foci formation and enhancing skin beauty. It is important to know amount and type of dietary sphingolipid for understanding mechanisms underlying these effects. In this study, we quantified glycosylinositol phosphoceramide (GIPC), one of major plant sphingolipids, in foodstuffs. We found that GIPC was contained in all vegetables examined (13 kinds of vegetables) at a rage from 3 to 20 mg/100 g (wet weight), but not in meats and eggs. Daily intake of GIPC was estimated to be approximately 28 mg/day, which is similar level to that of glycosylceramides. We also determined phytoceramide-1-phosphate (PC1P), a hydrolysate of GIPC, in vegetables. Relatively high amount of PC1P was detected in lipids from raw cabbage leaves and raw radish roots (5.2 and 2.3 mg/100 g, respectively). PC1P was found to be converted to phytoceramide by intestinal alkali phosphatase. From these results, it is considered that a portion of GIPC in cruciferous vegetables is absorbed via phytoceramide after conversion of GIPC to PC1P by endogenous GIPC-specific phospholipase D.