MATERIALS AND METHODS

General Procedure IR spectra were recorded on Shimadzu FTIR-8400 infrared spectrophotometer. FAB-MS spectra were measured on a JEOL JMS-HX 100 instrument. Electrospray ionization mass spectra (ESI-MS) were measured on an API-3000 mass spectrometer (Applied Biosystems) fitted with a TurboionsprayTM interface. 1H-NMR spectra were recorded on JEOL EX-400 (400MHz) instruments using tetramethylsilane as an internal standard. Analytical TLC and preparative TLC were performed using Silica gel 60 F254 (Merck, 0.25 and 0.5 mm, respectively) glass plates. Column chromatography was performed using Silica Gel 60 (70—230 mesh ASTM). All extracted solvents were dried over Na2SO4, followed by evaporation in vacuo. Materials and Chemicals Sphingosine and DMS were purchased from Wako Pure Chemical Industries, Ltd.(Osaka, Japan) and sphingosine-1-P was obtained from the Kanto Chemical Co., Inc.(Tokyo, Japan). ISP-I-55 was prepared previously by one of our co-workers (T. Fujita). 17) FTY720