linoleic-acid and 11-hydroxy-9-12-octadecadienoic-acid

When the sewage fungus Leptomitus lacteus was grown in liquid culture aerobically and then transferred to medium containing long-chain fatty acids, it produced a number of oxygenated fatty acids. From linoleic acid (18:2n-6), the major metabolite produced was R-8-hydroxy-9Z,12Z-octadecadienoic acid (8R-HODE), with additional quantities of 8,11-di-HODE, 11,16-di-HODE, and 11,17-di-HODE. Other fatty acid derivatives identified included 7-HODE, 10-HODE, and 13-hydroxy-octadecamonoenoic acid. Arachidonic acid (20:4n-6) was metabolized primarily to 18- and 19-hydroxy-eicosatetraenoic acids (18- and 19-HETE) also as R enantiomers, along with smaller quantities of 17-HETE, 9-HETE, 14,15-dihydroxy-eicosatrienoic acid and 11,12,19-trihydroxy-eicosatrienoic acid. The oxygenated products of long-chain fatty acids, in particular the biosynthesis of 8R-HODE, a compound classified as a precocious sporulation inducer, were similar to those produced by an unrelated fungal species in the Ascomycota, the take-all fungus Gaeumannomyces graminis. As in G. graminis, the biotransformation of linoleate to 8R-HODE was not significantly inhibited by exposure of the organism to CO. This indicated that the enzyme responsible for 8R-HODE biosynthesis in Leptomitus could be similar to that of G. graminis; yet we did not detect 7,8-di-HODE as a product of 18:2n-6 metabolism as in G. graminis. CO did inhibit the biosynthesis of 14,15-di-HETE, 18-HETE, and 19-HETE in L. lacteus, which suggested the involvement of a cytochrome P450-type monooxygenase. The biosynthesis of 8R-HODE from 18:2n-6 was found to occur in certain cell lysates, specifically in low speed (15,000 x g) supernatant, following cell disruption.

Topics: Arachidonic Acid; Hydroxyeicosatetraenoic Acids; Linoleic Acid; Linoleic Acids; Oomycetes; Oxygen; Sewage

Bisallylic carbons of polyunsaturated fatty acids can be hydroxylated in NADPH-dependent reactions in liver microsomes. Human recombinant cytochromes P450 and human and rat liver microsomes were assayed for bisallylic hydroxylation activity. CYP1A2, CYP2C8, CYP2C9, CYP2C19 and CYP3A4 converted [14C]linoleic acid to 14C-labeled 11-hydroxyoctadecadienoic acid (11-HODE), whereas [14C]arachidonic acid was oxygenated by CYP1A2 and CYP3A4 to 14C-labeled 13-hydroxyeicosatrienoic acid (13-HETE), 10-HETE and 7-HETE as determined by HPLC. Both substrates were also converted to many other metabolites. CYP2C9 appeared to form 12R-HETE and 13-HETE, whereas CYP2C8 formed 13-HETE, 11-HETE and 15-HETE as main monohydroxy metabolites. Fetal human liver microsomes metabolized linoleic acid to 11-HODE as a major hydroxy metabolite, whereas arachidonic acid appeared to be hydroxylated at C13, C20 and, to some extent, at C10, C19 and C7. Fetal liver microsomes mainly formed 13R-HETE, whereas adult human liver microsomes and CYP1A2 mainly formed 13S-HETE. 7,8-Benzoflavone (5 microM) and furafylline (20 microM), two inhibitors of CYP1A2, reduced the bisallylic hydroxylation activity of adult human liver microsomes. Treatment of rats with erythromycin or dexamethasone induced bisallylic hydroxylation of linoleic acid to 11-HODE in liver microsomes by 2- and 10-fold, respectively. The biosynthesis of 11-HODE by microsomes of dexamethasone-treated rats was inhibited by troleandomycin (ED50 = 1 microM) and by polyclonal antibodies against CYP3A1, suggesting that CYP3A1 could catalyze bisallylic hydroxylations in the dexamethasone-treated rat. We conclude from steric analysis of 13-HETE and the effects of CYP inhibitors on adult human liver microsomes that CYP1A2 might contribute to its bisallylic hydroxylation activity.

Topics: Animals; Arachidonic Acid; Aryl Hydrocarbon Hydroxylases; Cytochrome P-450 CYP3A; Cytochrome P-450 Enzyme System; Female; Gas Chromatography-Mass Spectrometry; Humans; Hydroxyeicosatetraenoic Acids; Hydroxylation; Linoleic Acid; Linoleic Acids; Male; Microsomes, Liver; Rats; Rats, Inbred F344; Recombinant Proteins

Topics: Adult; Animals; Arachidonic Acid; Cytochrome P-450 Enzyme System; Dexamethasone; Erythromycin; Fetus; Humans; Hydroxylation; Isoenzymes; Linoleic Acid; Linoleic Acids; Microsomes, Liver; Rats; Rats, Inbred F344; Recombinant Proteins

[14C]Linoleic acid was incubated with human liver microsomes and NADPH and biosynthesis of allylic hydroxy fatty acids was investigated. 11-Hydroxy-9Z,12Z-octadecadienoic acid (11-HODE), 9-hydroxy-10E,12Z-octadecadienoic acid (9-HODE), 13-hydroxy-9Z,11E-octadecadienoic acid (13-HODE) and 14-hydroxy-9Z,12Z-octadecadienoic acid were identified. 9-HODE and 13-HODE were formed with stereoselectivity (80% R) provided that 11-HODE was prevented from decomposing to 9(R,S)-HODE and 13(R,S)-HODE by extractive isolation at pH 5-6. Human hepatic microsomes metabolized [14C]arachidonic acid to many products, including 13-HETE and small amounts of 15-HETE (> 90% R), 11-HETE (59% R) and 12-HETE (> 90% R). Hepatic microsomes of untreated rats metabolized [14C]linoleic acid to 11-HODE as a major product, but significant formation of 11-HODE by purified cytochrome P-450 (P450) (CYP1A1, CYP2B1, CYP2B4, CYP2E1, CYP3A6 and CYP4A1) in a reconstituted system could not be detected, indicating that 11-HODE might be formed by other and constitutive P450 isozymes.

Topics: Animals; Arachidonic Acid; Chromatography, High Pressure Liquid; Cytochrome P-450 Enzyme System; Gas Chromatography-Mass Spectrometry; Humans; Hydroxyeicosatetraenoic Acids; Hydroxylation; Linoleic Acid; Linoleic Acids; Liver; Male; Microsomes, Liver; Rats; Rats, Sprague-Dawley; Stereoisomerism