[Synthesis and platelet aggregating activity of structural analogs of platelet-activating factor with a heterocyclic head group].

Structural analogues of platelet-activating factor (PAF, 1-O-alkyl-2-O-acetyl-sn-glycero-3-phosphocholine) containing an imidazole or thiazole residue as polar head group have been prepared and tested for platelet aggregating properties. Compared with PAF all analogues exert considerably lower platelet-stimulating activities. The agonistic behaviour is shown to depend primary on the presence of a positively charged polar head group.