Biosynthesis of Prostaglandin D2,15-ketoprostaglandin E2, and Hydroxy Fatty Acids by Ram Seminal Vesicle Microsomes

At high arachidonic acid concentrations (164 μM) and without exogenous cofactors, ram seminal vesicle microsomes produced prostaglandin E2 and two less polar products, identified as prostaglandin D2 and 15-ketoprostaglandin E2. The ratio of the biosynthetic products formed depended on the exogenous cofactor and on the arachidonic acid concentration. At high arachidonic acid concentrations (>150 μM), tryptophan, phenol, and glutathione stimulated prostaglandin E2 formation, but each affected the formation of the other prostaglandins differently. Ascorbic acid markedly stimulated hydroxy fatty acid formation. GLC-mass spectral analysis of the hydroxy fatty acid fraction indicated the presence of 11-hydroxy-5,8,12,14-eicosatetraenoic acid, 15-hydroxy-5,8,11,13-eicosatetraenoic acid, and 12-hydroxy-5,8,10-heptadecatrienoic acid. At low arachidonic acid concentrations (30 μM). glutathione still stimulated prostaglandin E2 biosynthesis, but the other cofactors stimulated 6-ketoprostaglandin F1α”︁ and hydroxy fatty acid formation.