Omega 6-oxygenation of 6, 9, 12-octadecatrienoic acid in human platelets

[1-14C]6, 9, 12-Octadecatrienoic acid was incubated with suspensions of human platelets. Three monohydroxy acids were isolated, i.e. 10LS-hydroxy-6, 8-pentadecadienoic acid, 10LS-hydroxy-6, 8, 12-octadecatrienoic acid, and 13LS-hydroxy-6, 9, 11-octadecatrienoic acid. Aspirin (0.5 mM) and indomethacin (10 microM) completely inhibited formation of the first mentioned compound whereas 5, 8, 11, 14-eicosatetraynoic acid (34 microM) inhibited formation of all three compounds. Isolation of 13LS-hydroxy-6, 9, 11-octadecatrienoic acid demonstrates that human platelets possess a lipoxygenase activity catalyzing omega 6-oxygenation of suitable poly-unsaturated fatty acids.