title: Cooxidation of 13-cis-retinoic acid by prostaglandin H synthase.
abstract: Cooxidative metabolism of 13-cis-retinoic acid (13-CIS) via prostaglandin H synthase was investigated employing ram seminal vesicle microsomes. Oxidation of 13-CIS utilizing H2O2, 13-hydroperoxy-9-cis-11-trans-octadecadienoic acid (13-OOH-18:2), or 1-hydroperoxy-5-phenyl-4-pentene was detected by measurement of O2 incorporation. UV spectroscopy and HPLC of extracted incubation mixtures demonstrated that 13-CIS was metabolized to oxidized derivatives. Similar spectral changes and HPLC profiles were obtained with H2O2, 13-OOH-18:2, or arachidonic acid as substrates. 4-Hydroxy-13-cis-retinoic acid and all trans-retinoic acid were products of cooxidation as well as other polar metabolites. Oxidation was inhibited by the antioxidant butylated hydroxyanisole and the spin trap, nitrosobenzene. These results indicate that 13-cis-retinoic acid is cooxidized by prostaglandin H synthase and suggest a free radical mechanism resembling that of lipid peroxidation.
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D007536:Isomerism; D015474:Isotretinoin; D008297:Male; D010084:Oxidation-Reduction; D011451:Prostaglandin-Endoperoxide Synthases / Q000378:metabolism*; D012669:Seminal Vesicles / Q000201:enzymology; D012756:Sheep; D013056:Spectrophotometry, Ultraviolet; D013379:Substrate Specificity; D014212:Tretinoin / Q000378:metabolism*
chemical_list: D014212:Tretinoin; D011451:Prostaglandin-Endoperoxide Synthases; D015474:Isotretinoin