title: Chiral analysis of 12-hydroxyeicosatetraenoic acid formed by calf corneal epithelial microsomes.
abstract: The production of 12-hydroxyeicosatetraenoic acid by the corneal epithelium of several species has been extensively reported yet the controversy over the exclusive production of the (S) epimer (a lipoxygenase-derived metabolite) endures. Incubation of calf corneal epithelial microsomes (3 mg/ml) with arachidonic acid and NADPH resulted in the formation of 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE). The synthesis of 12-HETE was inhibited by SKF-525A and clotrimazole, selective inhibitors of cytochrome P450 dependent activities, but not by indomethacin or BW-755C, inhibitors of cyclooxygenase and lipoxygenase activities, respectively. Chiral analysis revealed the presence of both enantiomers; however, the R isomer was the predominant one, i.e., 91 +/- 5% vs. 9 +/- 5% for the R and S enantiomers, respectively. Since the R enantiomer is the product of a cytochrome P450-mediated reaction, it suggests that the major metabolic activity in these microsomes is cytochrome P450-dependent and supports the claim for cytochrome P450 reactions in this ocular tissue.
authors.affiliation: Department of Pharmacology, New York Medical College, Valhalla, USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Conners
authors.forename: R A
authors.initials: RA
authors.lastname: Stoltz
authors.forename: M L
authors.initials: ML
authors.lastname: Schwartzman
mesh_terms: D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid / Q000096:biosynthesis* / Q000737:chemistry*; D000818:Animals; D016718:Arachidonic Acid / Q000494:pharmacology; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003315:Cornea / Q000187:drug effects / Q000378:metabolism*; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004728:Endothelium, Corneal / Q000187:drug effects / Q000378:metabolism; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism*; D009249:NADP / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D016718:Arachidonic Acid; D009249:NADP; D019377:12-Hydroxy-5,8,10,14-eicosatetraenoic Acid; D003577:Cytochrome P-450 Enzyme System