7324-21-2

Upstream product

• 60900-56-3 methyl 9Z,11E-13-hydroperoxyoctadecadienoate 
• 63121-48-2 (9E,11E,13R,S)-13-hydroperoxy-9,11-octadecadienoic acid 
• 60-33-3 linoleic acid 
• 6542-05-8 1,2-Dilinoleoyl-sn-glycerol-3-phosphorylcholine 
• 112-63-0 Methyl linoleate 

Downstream Products

• 10219-69-9 (R,S)-coriolic acid 
• 63121-48-2 (9E,11E,13R,S)-13-hydroperoxy-9,11-octadecadienoic acid 
• 63121-49-3 (9R,S,10E,12E)-9-hydroperoxy-10,12-octadecadienoic acid 
• 73036-16-5 (13R,9Z,11E)-13-hydroperoxy-9,11-octadecadienoic acid 
• 169217-38-3 12-[1′(E)-hexenyloxy]-9(Z),11(E)-dodecadienoic acid 
• 32819-31-1 [14C]-13-Hydroxyoctadecadienoic acid 

Relevant academic research and scientific papers

Development and Application of a Peroxyl Radical Clock Approach for Measuring Both Hydrogen-Atom Transfer and Peroxyl Radical Addition Rate Constants

The rate-determining step in free radical lipid peroxidation is the propagation of the peroxyl radical, where generally two types of reactions occur: (a) hydrogen-atom transfer (HAT) from a donor to the peroxyl radical; (b) peroxyl radical addition (PRA) to a C=C double bond. Peroxyl radical clocks have been used to determine the rate constants of HAT reactions (kH), but no radical clock is available to measure the rate constants of PRA reactions (kadd). In this work, we modified the analytical approach on the linoleate-based peroxyl radical clock to enable the simultaneous measurement of both kH and kadd. Compared to the original approach, this new approach involves the use of a strong reducing agent, LiAlH4, to completely reduce both HAT and PRA-derived products and the relative quantitation of total linoleate oxidation products with or without reduction. The new approach was then applied to measuring the kH and kadd values for several series of organic substrates, including para- and meta-substituted styrenes, substituted conjugated dienes, and cyclic alkenes. Furthermore, the kH and kadd values for a variety of biologically important lipids were determined for the first time, including conjugated fatty acids, sterols, coenzyme Q10, and lipophilic vitamins, such as vitamins D3 and A.

Characterization of Bitter-Tasting Oxylipins in Poppy Seeds (Papaver somniferum L.)

Activity-guided fractionation of poppy seed (Papaver somniferum L.) extracts and analysis of fatty acid oxidation model experiments, followed by liquid chromatography time-of-flight mass spectrometry, tandem mass spectrometry, and one-/two-dimensional nuclear magnetic resonance experiments, revealed the chemical structures of five bitter-tasting fatty acids (1-5), three monoglycerides (6-8), six C18-lipidoxidation products (9-14), and four lipid oxidation degradation products (15 and 17-19) as well as two previously unreported monoglyceride oxidation degradation products, namely, 9-(2′,3′-dihydroxypropyloxy)-9-oxononaic acid (1-azeloyl-rac-glycerol, 16) and 1-(2′,3′-dihydroxypropyl)-8-(5″-oxo-2″,5″-dihydrofruan-2″-yl)-octonoate (1-ODFO-rac-glycerol, 20). Sensory studies exhibited low bitter taste threshold concentrations between 0.08 and 0.29 mmol/L, particularly for the higher oxidated C18-fatty acids trihydroxyoctadecenoic acid (THOE, 12), 12,13-dihydroxy-9-oxo-10-octadecenoic acid (12,13-diOH-9-oxo, 13), and 9,10-dihydroxy-13-oxo-11-octadecenoic acid (9,10-diOH-13-oxo, 14) as well as for the lipidoxidation degradation products 4-hydroxy-2-noneic acid (4-HNA, 17), 4-hydroxy-2-docecendienoic acid (HDdiA, 18), and 8-(5′-oxo-2′,5′-dihydrofuran-2′-yl)-octanoic acid (ODFO, 20).

Reaction targets of antioxidants in azo-initiator or lipid hydroperoxide induced lipid peroxidation

Lipid peroxidation (LPO) is reported to be involved in the pathogenesis of several oxidative diseases, and several therapeutic approaches using antioxidants have been proposed. LPO is thought to progress via a complicated series of multistep reactions suggesting that the activity of each antioxidant may be different, and depends on the reacting molecules. Hence, in this study, we evaluated the inhibitory mechanisms of several antioxidants toward arachidonic acid (AA) peroxidation induced by the azo initiator 2,2’-azobis(2-amidinopropane) dihydrochloride (AAPH) or a lipid hydroperoxide, hydroperoxyoctadecadienoic acid (HpODE)/hemin. Edaravone, ferrostatin-1, TEMPO and trolox effectively inhibited the production of malondialdehyde (MDA) and several oxidised AAs generated in the AAPH-induced LPO because of their scavenging ability toward lipid peroxyl radicals. In contrast, ebselen and ferrostatin-1 showed strong antioxidative activity in the HpODE/hemin-induced peroxidation. Under this condition, ebselen and ferrostatin-1 were thought to reduce HpODE and its derived alkoxyl radicals to the corresponding lipid alcohols. In conclusion, we found that each antioxidant had different antioxidative activities that prevented the progression of LPO. We expect that these findings will contribute to the design of novel therapeutic strategies using an appropriate antioxidant targeted to each step of the development of oxidative stress diseases.

Catalytic production of oxo-fatty acids by lipoxygenases is mediated by the radical-radical dismutation between fatty acid alkoxyl radicals and fatty acid peroxyl radicals in fatty acid assembly

Oxo-octadecadienoic acids (OxoODEs) act as peroxisome proliferator-activated receptor (PPAR) agonists biologically, and are known to be produced in the lipoxygenase/linoleate system. OxoODEs seem to originate from the linoleate alkoxyl radicals that are generated from (E/Z)-hydroperoxy octadecadienoic acids ((E/Z)HpODEs) by a pseudoperoxidase reaction that is catalyzed by ferrous lipoxygenase. However, the mechanism underlying the conversion of alkoxyl radical into OxoODE remains obscure. In the present study, we confirmed that OxoODEs are produced in the lipoxygenase/linoleate system in an oxygen-dependent manner. Interestingly, we revealed a correlation between the (E/Z)-OxoODEs content and the (E/E)-HpODEs content in the system. (E/E)-HpODEs could have been derived from (E/E)-linoleate peroxyl radicals, which are generated by the reaction between a free linoleate allyl radical and an oxygen molecule. Notably, the ferrous lipoxygenase-linoleate allyl radical (LOx(Fe2+)-L·) complex, which is an intermediate in the lipoxygenase/linoleate system, tends to dissociate into LOx(Fe2+) and a linoleate allyl radical. Subsequently, LOx(Fe2+) converts (E/Z)-HpODEs to an (E/Z)-linoleate alkoxyl radical through one-electron reduction. Taken together, we propose that (E/Z)-OxoODEs and (E/E)-HpODEs are produced through radical-radical dismutation between (E/Z)-linoleate alkoxyl radical and (E/E)-linoleate peroxyl radical. Furthermore, the production of (E/Z)OxoODEs and (E/E)-HpODEs was remarkably inhibited by a hydrophobic radical scavenger, 2,2,6,6-tetra-methylpiperidine 1-oxyl (TEMPO). On the contrary, water-miscible radical scavengers, 4-hydroxyl-2,2,6,6-tetramethylpiperidine 1-oxyl (OH-TEMPO) and 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrroline-N-oxyl (CmΔP) only modestly or sparingly inhibited the production of (E/Z)-OxoODEs and (E/E)-HpODEs. These facts indicate that the radical-radical dismutation between linoleate alkoxyl radical and linoleate peroxyl radical proceeds in the interior of micelles.

Ascorbic acid 6-palmitate: A potent inhibitor of human and soybean lipoxygenase-dependent lipid peroxidation

Objectives Lipoxygenases (LOX) are the key enzymes involved in the biosynthesis of leukotrienes and reactive oxygen species, which are implicated in pathophysiology of inflammatory disorders. This study was conducted to evaluate the inhibitory effect of water-soluble antioxidant ascorbic acid and its lipophilic derivative, ascorbic acid 6-palmitate (Vcpal) on polymorphonuclear lymphocyte 5-LOX and soybean 15-LOX (sLOX) in vitro. Methods LOX activity was determined by measuring the end products, 5-hydroperoxy eicosatetraenoic acid (5-HETE) and lipid hydroperoxides, by spectrophotometric and high performance liquid chromatography methods. The substrate-dependent enzyme kinetics and docking studies were carried out to understand the nature of inhibition. Key findings Vcpal potently inhibited 5-LOX when compared with its inhibitory effect on sLOX (IC50; 2.5 and 10.3μm respectively, P= 0.003). Further, Vcpal inhibited 5-LOX more strongly than the known synthetic drugs: phenidone and nordihydroguaiaretic acid (P= 0.0007). Enzyme kinetic studies demonstrated Vcpal as a non-competitive reversible inhibitor of 5-LOX. In-silico molecular docking revealed high MolDock and Rerank score for Vcpal than ascorbic acid, complementing in-vitro results. Conclusion Both in-vitro and docking studies demonstrated Vcpal but not ascorbic acid as a non-competitive inhibitor of 5-LOX- and sLOX-induced lipid peroxidation, suggesting a key role for lipophilic nature in bringing about inhibition.

The autooxidation process in linoleic acid screened by Raman spectroscopy

The chemical changes associated to the autooxidation process of linoleic acid (LA) were detected by Raman spectroscopy and interpreted in the light of density functional theory (DFT) calculations performed for both the fatty acid and its main oxidation products. The present methodology, applied for a six-day period upon induction of oxidation (through heating), allowed to understand the chemical modifications occurring during the oxidation process. Raman spectroscopy was shown to be a suitable and reliable technique for assessing the oxidation degree of fatty acid samples, particularly pure fatty acids, mainly when computational methods are used alongside to predict the spectral features of the distinct chemical entities involved. Screening of the oxidation process was mostly based on the loss of intensity of the bands assigned to LA cis-double bonds. Copyright

In vitro inhibition of linoleic acid peroxidation by primary S-Nitrosothiols

Nitric oxide (*NO) is an effective chain-breaking antioxidant in the inhibition of lipid peroxidation and circulates in vivo mainly as primary S-nitrosothiols (RSNOs). In this work, the in vitro peroxidation of linoleic acid-SDS comicelles (LA-SDS) catalyzed by soybean lipoxygenase (SLO) and Fe II ions was monitored in the presence and absence of three primary RSNOs: S-nitrosocysteine, S-nitroso-N-acetylcysteyne and S-nitrosoglutathione. Kinetic measurements based on the formation of conjugated double bonds and fluorescent oxidized LA-lysine adducts, showed that RSNOs are more potent antioxidants than their corresponding free thiols (RSHs) in equimolar conditions. These results are consistent with the blocking of LA-SDS peroxidation by RSNOs through the inactivation of peroxyl/alkoxyl (LOO*/LO*) radicals, leading to nitrogen-containing products of oxidized LA, which release free *NO. These results indicate that endogenous RSNOs may play a major role in the blocking of lipid peroxidation in vivo, through the primary inactivation of alkoxyl/peroxyl radicals and also of preformed lipid hydroperoxides.

Proteins modified by the lipid peroxidation aldehyde 9,12-dioxo-10(E)- dodecenoic acid in MCF7 breast cancer cells

The hydroperoxide of linoleic acid (13-HPODE) degrades to 9,12-dioxo-10(E)-dodecenoic acid (DODE), which readily modifies proteins. This study identified the major proteins in MCF7 cells modified by DODE. To reduce false positives, three methods were used to identify DODE-modified proteins. First, cells were treated with a synthetically biotinylated 13-HPODE (13-HPODE-biotin). Modified proteins were enriched by neutravidin affinity and identified by two-dimensional liquid chromatography-tandem mass spectrometry (2D LC-MS/MS). Second, cells were treated with native 13-HPODE. Protein carbonyls were biotinylated with an aldehyde reactive probe, and modified proteins were enriched by neutravidin affinity and identified by 2D LC-MS/MS. Third, using a newly developed DODE antibody, DODEmodified proteins were located by 2D sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blot and identified by in-gel digestion and LC-MS/MS. Analysis of the proteins characterized by all three methods revealed a significant overlap and identified 32 primary proteins modified by DODE in MCF7 cells. These results demonstrated the feasibility for the cellular formation of DODE protein-carbonyl adducts that may be future indicators of oxidative stress.

Quantitation of hydroperoxy-, keto- and hydroxy-dienes during oxidation of FAMEs from high-linoleic and high-oleic sunflower oils

The objective of this work was to study the quantitative formation of hydroperoxydienes, ketodienes and hydroxydienes during autoxidation at 40 °C of fatty acid methyl esters derived from two sunflower oils with different degree of unsaturation, high-linoleic sunflower oil and high-oleic sunflower oil. The analysis of the oxidation compounds was carried out by NP-HPLC-UV and results were compared to the specific extinction at 232 nm (K 232) and the peroxide value (PV). Analysis of FAME polymers by HPSEC was also performed to discard samples of advanced oxidation. Results showed that the contents of hydroperoxydienes with respect to the PV were higher for the high linoleic (HL) sample. At the end of the period of slow polymerization (ΔPol ≤ 1 wt%), the content of hydroperoxydienes was found to be 86.0 and 30.7 μg/mg for the HL and high oleic (HO) samples, respectively. Throughout this period, hydroperoxydienes constituted around 90 and 50 wt% of the total hydroperoxides in the HL and HO samples, respectively, suggesting that a significant oxidation of oleic acid also occurred in both samples. The contents of ketodienes and hydroxydienes as a whole constituted 2-3 wt% of the diene compounds analyzed at the end of the period of slow polymerization. Higher contents of ketodienes than of hydroxydienes were found throughout the oxidation time, and the ratio between the contents of ketodienes and hydroxydienes increased with a factor that changed from 1 to 2 throughout the period of slow polymerization.

Rate constants for peroxidation of polyunsaturated fatty acids and sterols in solution and in liposomes

Rate constants for autoxidation propagation of several unsaturated lipids in benzene solution at 37°C and in phosphatidylcholine liposomes were determined by a linoleate radical clock. This radical clock is based on competition between hydrogen atom abstraction by an intermediate peroxyl radical derived from linoleic acid that leads to a trans,cis-conjugated hydroxyoctadecadienoic product and β-fragmentation of the same peroxyl that gives the trans,trans-product hydroxyoctadecadienoic acid. Rate constants determined by this approach in solution relative to linoleic acid (k p) 62 M-1 s-1) were: arachidonic acid (k p = 197 ± 13 M-1 s-1), eicosapentaenoic acid (kp = 249 ± 16 M-1 s-1), docosahexaenoic acid (kp = 334 ± 37 M-1 s -1), cholesterol (kp= 11 ± 2 M-1 s -1), and 7-dehydrocholesterol (kp = 2260 ± 40 M-1 s-1). Free radical oxidations of multilamellar and unilamellar liposomes of various mixtures of glycerophosphatidylcholine molecular species were also carried out. In some experiments, cholesterol or 7-dehydrocholesterol was incorporated into the lipid mixture undergoing oxidation. A phosphatidylcholine bearing a linoleate ester at sn-2 was a component of each liposome peroxidation reaction and the ratio of trans,cis/trans,trans (t,c/t,t)-conjugated diene oxidation products formed from this phospholipid was determined for each oxidation reaction. This t,c/t,t-product ratio from linoleate was used to "clock" liposome constituents as hydrogen atom donors in the lipid bilayer. Application of this lipid bilayer radical clock gives relative autoxidation propagation rate constants of arachidonate (20:4), eicosapentaenoate (20:5), docosahexaenoate (22:6), and 7-dehydrocholesterol to be 115 ± 7, 145 ± 8, 172 ± 13, and 832 ± 86, respectively, a reactivity trend that parallels the one in solution. We also conclude from the liposome oxidations that linoleate peroxyl radicals at different positions on the eighteen-carbon chain (at C-9 and C-13) have different kinetic properties. This is in contrast to the results of solution oxidations of linoleate in which the C-9 and C-13 peroxyl radicals have similar reactivities. We suggest that peroxyl radical β-scission depends on solvent polarity and the polarity of the local environment of peroxyl radicals in liposomal oxidations depends on the position of the peroxyl radical on the 18-carbon chain.