HIGH-LEVEL OF 1-O-ALKYL-LINKED GLYCEROPHOSPHOCHOLINE (PLATELET-ACTIVATING-FACTOR PRECURSOR) IN A MARINE GASTROPOD, APLYSIA-KURODAI

A water-insoluble lipid (SM-1) containing phosphocholine was isolated from the skin of a marine gastropod, Aplysia kurodai. SM-1 was purifie d from Folch's lower-phase material of the skin of A. kurodai using tw o solvent systems of column chromatography on silicic acid. Based on t he results of thin-layer chromatography, chemical analysis, IR absorpt ion spectrometry, and fast atom bombardment-mass spectrometry, the str ucture of SM-1 was identified as 1-O-alkyl-2-acyl (long chain)-sn-glyc ero-3-phosphocholine (alkylacyl-GPC), which is regarded as a precursor of the platelet-activating factor (PAF). Fatty chains at positions 1 and 2 of SM-1 were analyzed by capillary gas-liquid chromatography. Th e 1-O-alkyl fatty chain consisted principally of 16:0, whereas the 2-a cyl fatty acid chain consisted of 16:0, 18:1, 20:1, 20:4 and 22:4 as m ajor components and 16:1, 17.1 and 18:0 as minor components. These dat a provide evidence that SM-1 is present in the skin, nervous tissue an d hemolymph of A. kurodai, and suggest these tissues contain a precurs or for the synthesis of PAF.