Transformations of 5,8,11,14,17-eicosapentaenoic acid in human platelets

5,8,11,14,17-[1-14C]Eicosapentaenoic acid was prepared biosynthetically from [1-14C]arachidonic acid using the fungus, Saprolegnia parasitica. Incubation of 5,8,11,14,17-[1-14C]eicosapentaenoic acid with suspensions of human platelets led to the formation of three labeled compounds which were identified as thromboxane B3 (2-5% yield), 12-hydroxy-5,8,10,14-heptadecatetraenoic acid (2-5% yield), and 12-hydroxy-5,8,10,14,17-eicosapentaenoic acid (7-59% yield).