Platelet-stimulating and membranolytic properties of racemic PAF-acether and analogues

Three synthetic 1-O-hexadecyl-rac-glycero-3-phosphocholines and the corresponding 1-O-hexadecyl-rac-glycero-3-phosphoric acid methyl esters were tested for platelet-aggregatory and membranolytic properties. Nanomolar concentrations of both the 2-O-acetyl and the 2-O-propionyl derivative of 1-O-hexadecyl-rac-glycero-3-phosphocholine were shown to activate platelets in human platelet-rich plasma. About 625-fold higher concentrations of the corresponding phosphoric acid methyl esters are required to produce the same platelet-stimulating effect. The 1-O-hexadecyl-rac-glycero-3-phosphocholine and the 1-O-hexadecyl-rac-glycero-3-phosphoric acid methyl ester are both nearly ineffective up to final concentrations of 0.1 to 0.2 mM. All tested compounds also cause a graduated lysis of red cells in the range of micromolar concentrations.