New total synthesis and high resolution 1H NMR spectrum of platelet-activating factor, its enantiomer and racemic mixtures.

A new method of synthesis of octadecyl platelet-activating factor (PAF; 1-O-octadecyl 2-O-acetyl sn-glycero-3-phosphorylcholine) is described. Its advantage is to proceed by way of the 'lyso-PAF' which may be substituted by various groups, while avoiding the inconveniences of the total synthesis already described. Moreover, the intermediates in synthesis are easier to purify, with better yields. The platelet-aggregating activity of synthetic PAF, is enantiomer (3-O-octadecyl) and racemic mixtures were 2.7 . 10(-10), 1.7 . 10(-7) and 2.2 . 10(-10) M, respectively. These results indicate the stereospecificity of platelet activation induced by PAF.