Sphingomyelin inhibits platelet 12-lipoxygenase activity.

The effect of sphingomyelin on the formation of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), thromboxane B2 and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT) in washed rabbit platelets was examined. Sphingomyelin had a powerful inhibitory effect on 12-HETE formation, while it produced only a small increase in thromboxane B2 and HHT formation. The sphingomyelin metabolite ceramide did not affect the formation of 12-HETE, thromboxane B2 and HHT. These results suggest that sphingomyelin is a selective inhibitor of platelet 12-lipoxygenase and may have functional effects in platelets.