Determination of sphingolipids in nuts and seeds by a single quadrupole liquid chromatography-mass spectrometry method

Studies with experimental animals have shown that dietary sphingolipids significantly reduce the early stages of colon carcinogenesis and tumor formation, but knowledge about the amount and structure of sphingolipids in foods, especially foods of plant origin, is sparse because of lack of effective identification and quantification methods. Also, it is critical to know the structure of sphingolipids in plants in order to understand the potential link between diet and cancer. In this study, we developed a liquid chromatography-mass spectrometry method with atmospheric pressure chemical ionization positive ion mode to separate, identify and quantify ceramide and cerebroside species simultaneously in 10 plant samples. The ceramides found in the samples contained mainly trihydroxy bases, especially 4-hydroxy-8- sphingenine (t18:1). Both nonhydroxy fatty acids and hydroxy fatty acids were found, and these were mostly very long chain fatty acids (C > 20). Cerebrosides of the plant samples had both dihydroxy and trihydroxy bases, with dihydroxy base 4,8-sphingadienine (d18:2) dominating. The fatty acids were composed mainly of -hydroxy fatty acids. Using an external calibration method, the major cerebroside found in the plants examined was quantified. This is the first report of sphingolipid content in most of the species studied. © Copyright 2005, Blackwell Publishing.