Synthesis and Biosynthesis of Alkoxylipids

Chromatographic methods have shown that lipids with long alkyl or 1‐alkenyl chains–called alkoxylipids or ether lipids–are widely distributed in human and animal tissues. These compounds comprise neutral alkoxylipids, i. e. 1‐O‐alkyl or 1‐O‐(1‐alkenyl)‐2,3‐di‐O‐acylglycerols, and alkoxylipids which are linked by a phosphate residue at C‐3 to aminoethanol, choline or serine. 1‐O‐Alkylglycerols, 1‐O‐(1‐alkenyl)glycerols and other natural alkoxylipids can be synthesized in high yields. 2‐Alkyl, 1,3‐dialkyl and trialkylglycerols which are not found in nature are also accessible by synthesis. The neutral alkoxylipids are employed in biomedical investigations, e.g. as substrates in acyl‐hydrolase systems or in fat absorption studies. The principal features of alkoxylipid biosynthesis have been elucidated. The alkyl residue is derived from a saturated or monounsaturated fatty acid via the corresponding alcohol. 1‐O‐(1‐alkenyl)‐2‐O‐acylglycerophosphoryl aminoethanols (“plasmalogens”) are apparently formed from the appropriate 1‐alkyl compounds; this is not possible in the case of the choline series. Both “aminoethanol” and “choline” plasmalogens are, nevertheless, present in most tissues.