Isotopic labeling of phosphatidylcholine in the choline moiety.

Two simple methods for the synthesis of phosphatidylcholine (lecithin) isotopically labeled in the methyl group of the choline moiety are described. Phosphatidylcholine is converted to phosphatidyl-ethanolamine by enzymic transphosphatidylation, and this is methylated using either methyl iodide or diazomethane to give a product isotopically enriched in all three choline methyl groups.