Regiospecific and enantioselective metabolism of 8,9-epoxyeicosatrienoic acid by cyclooxygenase.

8(S),9(R)-epoxyeicosatrienoic acid, a major product of the renal cortex, was found to be a substrate for cyclooxygenase from human platelets and ram seminal vesicles. 11(R)-hydroxy-8(S),9(R)-epoxyeicosatrienoic acid was the sole metabolic product. The 8(R),9(S)-enantiomer formed both C-11 and C-15 hydroxylated metabolites. These novel findings suggest that the cyclooxygenase-dependent renal vasoconstrictor activity of 8(S),9(R)-epoxyeicosatrienoic acid may be due to the 11(R)-hydroxy metabolite.