9-hydroperoxy-11-12-octadecadienoic-acid and 9-hydroxy-10-12-octadecadienoic-acid

Peroxidation of PUFAs by a variety of endogenous and xenobiotic electrophiles is a recognized pathophysiological process that can lead to adverse health effects. Although secondary products generated from peroxidized PUFAs have been relatively well studied, the role of primary lipid hydroperoxides in mediating early intracellular oxidative events is not well understood.. Live cell imaging was used to monitor changes in glutathione (GSH) oxidation in HAEC expressing the fluorogenic sensor roGFP during exposure to 9-hydroperoxy-10E,12Z-octadecadienoic acid (9-HpODE), a biologically important long chain lipid hydroperoxide, and its secondary product 9-hydroxy-10E,12Z-octadecadienoic acid (9-HODE). The role of hydrogen peroxide (H. Exposure to 9-HpODE caused a dose-dependent increase in GSH oxidation in HAEC that was independent of intracellular or extracellular H. Long chain lipid hydroperoxides can directly alter cytosolic E. These results reveal a previously unrecognized consequence of lipid peroxidation, which may provide insight into disease states involving lipid peroxidation in their pathogenesis.

Topics: Cells, Cultured; Dose-Response Relationship, Drug; Glutathione; Glutathione Peroxidase; Humans; Hydrogen Peroxide; Linoleic Acids; Linoleic Acids, Conjugated; Oxidation-Reduction; Phospholipid Hydroperoxide Glutathione Peroxidase

LOOHs (lipid hydroperoxides) in oxLDL [oxidized LDL (low-density lipoprotein)] are potentially atherogenic compounds. Recently, H2S was identified as the third endogenous gasotransmitter in the vasculature. H2O2 is known to be destroyed by H2S. Assuming that H2S may also react with LOOHs, the results show that H2S can destroy LOOHs in oxLDL. The ability of LOOH-enriched LDL to induce HO-1 (haem oxygenase 1) in endothelial cells was abolished by H2S pretreatment. HPLC analysis showed that 9-HPODE [(9S)-hydroperoxy-(10E,12Z)-octadecadienoic acid], a compound found in oxLDL, was reduced to 9-HODE [(9S)-hydroxy-(10E,12Z)-octadecadienoic acid] in the presence of H2S. Thus H2S may act as an antiatherogenic agent by reducing LOOHs to the less reactive LOHs and could abrogate the pathobiological activity of oxLDL.

Topics: Analysis of Variance; Cells, Cultured; Chromatography, High Pressure Liquid; Dose-Response Relationship, Drug; Endothelial Cells; Gene Expression Regulation, Enzymologic; Heme Oxygenase-1; Humans; Hydrogen Sulfide; Linoleic Acids; Linoleic Acids, Conjugated; Lipid Peroxides; Lipoproteins, LDL; Malondialdehyde; Reverse Transcriptase Polymerase Chain Reaction; Thiobarbituric Acid Reactive Substances; Time Factors

A particular isoform of lipoxygenase (LOX) localized on lipid bodies was shown by earlier investigations to play a role in initiating the mobilization of triacylglycerols during seed germination. Here, further physiological functions of LOXs within whole cotyledons of cucumber (Cucumis sativus L.) were analyzed by measuring the endogenous amounts of LOX-derived products. The lipid-body LOX-derived esterified (13 S)-hydroperoxy linoleic acid was the dominant metabolite of the LOX pathway in this tissue. It accumulated to about 14 micromol/g fresh weight, which represented about 6% of the total amount of linoleic acid in cotyledons. This LOX product was not only reduced to its hydroxy derivative, leading to degradation by beta-oxidation, but alternatively it was metabolized by fatty acid hydroperoxide lyase leading to formation of hexanal as well. Furthermore, the activities of LOX forms metabolizing linolenic acid were detected by measuring the accumulation of volatile aldehydes and the allene oxide synthase-derived metabolite jasmonic acid. The first evidence is presented for an involvement of a lipid-body LOX form in the production of volatile aldehydes.

Topics: Aldehydes; Cotyledon; Cucumis sativus; Cyclopentanes; Fatty Acids, Unsaturated; Germination; Intramolecular Oxidoreductases; Isoenzymes; Linoleic Acids; Linoleic Acids, Conjugated; Lipid Peroxides; Lipoxygenase; Oxylipins; Seeds; Time Factors; Triglycerides; Volatilization

Low density lipoprotein that was oxidized by activated human monocytes was analyzed to determine the identity of oxidized fatty acids present and the conditions required for their formation. The oxidized lipids were also analyzed under conditions allowing preservation of their oxidation state. Using reversed-phase high performance liquid chromatography (HPLC) analysis of native and saponified lipid extracts of oxidized low density lipoprotein (LDL), we found that the major fatty acid oxidation product was esterified hydroperoxyoctadecadienoic acid (HPODE), the oxidized product of the most abundant polyunsaturated fatty acid in human LDL, linoleic acid. Although some esterified hydroxyoctadecadienoic acid (HODE) was also detected, the reduction of HPODE to HODE did not appear to be monocyte-dependent. Essentially all of the HPODE was found to be esterified with the majority being esterified to cholesterol followed by phospholipids and generally following the abundance of esterified linoleic acid within the lipid classes. The percent of cholesteryl linoleate converted to cholesteryl HPODE and cholesteryl HODE at the end of the 24-h incubation was determined to be approximately 13.5%. The formation of oxidized esterified linoleic acid in the LDL was shown to require immunological activation of the human monocytes, a previously observed requirement for general LDL oxidation in this culture system. The oxidized esterified linoleic acid was present in the supernatant with the LDL and was not cell-associated. HPODE formation on LDL was prevented by including superoxide dismutase (SOD) or eicosatetraynoic acid (ETYA) during the 24-h coincubation of activated monocytes with LDL whereas indomethacin was without effect. The analysis of the lipid oxidation products in oxidized LDL can provide insight into the mechanisms involved in oxidation of LDL by activated human monocytes.

Topics: Cholesterol Esters; Esterification; Humans; Hydroxyeicosatetraenoic Acids; In Vitro Techniques; Kinetics; Linoleic Acids; Linoleic Acids, Conjugated; Lipid Peroxides; Lipoproteins, LDL; Monocytes; Oxidation-Reduction; Thiobarbituric Acid Reactive Substances

Topics: Animals; Guinea Pigs; Hydrogen Peroxide; Linoleic Acids; Linoleic Acids, Conjugated; Luminescent Measurements; Macrophages; Male; Phagocytosis; Pulmonary Alveoli; Superoxides; Tetradecanoylphorbol Acetate

As guinea-pig pulmonary macrophages (PM) synthesize the linoleic acid metabolite 9-hydroxy-octadecadienoic acid (9-OH-Lin) under non-stimulated conditions in relatively large quantities, we investigated whether this product has an effect on the macrophage's own phagocytic cell function. 9-OH-Lin, and also its hydroperoxy precursor 9-hydroperoxy-octadecadienoic acid (9-OOH-Lin), influenced the generation of PM chemiluminescence, a measure of the production of reactive oxygen species. The generation of lucigenin-enhanced chemiluminescence by stimulated and non-stimulated PM was inhibited concentration-dependently. Inhibition was observed at concentrations as low as 10 nM. Since 9-OH-Lin and 9-OOH-Lin also inhibited the generation of chemiluminescence by a cell-free enzyme system, i.e. xanthine/xanthine oxidase, the inhibitory effects might represent a scavenging activity towards reactive oxygen species. 9-OH-Lin and 9-OOH-Lin did not influence other phagocytic cell functions, e.g. PM phagocytic capacity, the aggregatory response to the calcium ionophore A23187, or the release of lysosomal enzymes. The effects of 9-OH-Lin and 9-OOH-Lin could be ascribed to the hydroxy and hydroxyperoxy moiety, respectively, as evidenced by lack of effect of the native fatty acid linoleic acid. We conclude that the formation of 9-OH-Lin and 9-OOH-Lin by PM may represent a regulatory mechanism towards the cell's own activity by modulating reactive oxygen species.

Topics: Animals; Calcimycin; Cell Aggregation; Escherichia coli; Fatty Acids, Unsaturated; Guinea Pigs; Hydrogen Peroxide; In Vitro Techniques; Kinetics; Linoleic Acids; Linoleic Acids, Conjugated; Luminescent Measurements; Macrophages; Male; Phagocytosis; Superoxides; Tetradecanoylphorbol Acetate; Xanthine Oxidase; Zymosan