Linoleic hydroperoxide

Detection of cholesteryl linoleate hydroperoxides and phosphatidylcholine hydroperoxides 63... 

Chan, H.W.S. and Levett, G. (1977). Autoxidation of methyl linoleate. Separation and analysis of isomeric mixtures of methyl linoleate hydroperoxides and methyl hydrox-ylinoleates. Lipids 12, 99. 

Yagi, K., Ohkawa, H., Oshistii, N., Yamashita, M. and Nakashima, T. (1981). Lesion of aortic intima caused by intravenous administration of linoleic hydroperoxide. J. Appl. Biochem. 3, 58-61. 

Interaction of lipid hydroperoxides with DNA gives fluorescent products, which cause structural changes in the DNA. Of the fluorescent products formed in the reaction of methyl linoleate hydroperoxide with adenine, FeS04, and ascorbic acid the 4,5- and 2,5-dihydrooxadiazoles (198) and (199) have been identified <88BBA(962)37l>. 

Frankel, E.N. and Gardner, H.W. 1989. Effect of a-tocopherol on the volatile thermal decomposition products of methyl linoleate hydroperoxides. Lipids 24 603-608. 

Chan FIWS, Levett G, Matthew JA (1978) Thermal isomerisation of methyl linoleate hydroperoxides. Evidence of molecular oxygen as a leaving group in a radical rearrangement. J Chem Soc Chem Commun 756-757... 

Aldehyde Formation. Several investigators observed a marked dominance of hexanal in the volatile products of low-temperature oxidation. At the higher temperatures, however, 2,4-decadienal was the major aldehyde formed (19,20,21). Both aldehydes are typical scission products of linoleate hydroperoxides. Swoboda and Lea (20) explained this difference on the basis of a selective further oxidation of the dienal at the higher temperature, while Kimoto and Gaddis (19) speculated that the carbon-carbon bond between the carbonyl group and the double bond (Type B) is the most vulnerable to cleavage under moderate conditions of autoxidation, while scission at the carbon-carbon bond away from the olefinic linkage (Type A) is favored under stress such as heat or alkali. 

Interactions with Histidine. Imidazole lactic acid and imidazole acetic acid were identified as breakdown products when histidine was reacted with methyl linoleate, methyl linoleate hydroperoxide or hexanal for 3 weeks at 25°C and 51°C (33). It was postulated that these compounds were formed via free radical reactions. Two other products were also produced which yielded histidine upon acid hydrolysis. These were thought to be Schiff s base compounds arising... 

During the oxidation to form hydroperoxides, the natural cis,cis unsaturation of linoleate is converted to cis, trans and trans, trans isomers. Privett and co-workers (10) concluded that at least 90% of linoleate hydroperoxide preparations are conjugated. When the oxidation is conducted at 0°C the hydroperoxides are predominately cis, trans isomers, but room temperature oxidation produces a large amount of trans, trans unsaturation (11, 12). Ethyl or methyl linoleate hydroperoxides are relatively low melting and as a result purification by crystallization is difficult. Bailey and Barlow (13) prepared high melting p-phenylphenacyl linoleate, oxidized the ester in benzene solution, and isolated virtually pure hydroperoxide by crystallization. Infrared spectra of the 99% purity p-phenylphenacyl linoleate hydroperoxide correspond to a trans, trans conjugated isomer. 

Hopia, A.I., Huang, S.-W., and Frankel, E.N. 1996. Effect of a-Tocopherol and Trolox on the Decomposition of Methyl Linoleate Hydroperoxides. Lipids. 31 357-365. 

During the inhibited self-initiated autoxidation of methyl linoleate by a-Toc in solution, Niki and coworkers made the interesting observation that a-Toc acts as an antioxidant at low concentrations, but high concentrations (up to 18.3 mM) actually increased hydroperoxide formation due to a pro-oxidant effect. The pro-oxidant effect of a-Toc was observed earlier by Cillard and coworkers in aqueous micellar systems and they found that the presence of co-antioxidants such as cysteine, BHT, hydroquinone or ascor-byl palmitate inverted the reaction into antioxidant activity, apparently by reduction of a-To" to a-Toc . Liu and coworkers ° found that a mixture of linoleic acid and linoleate hydroperoxides and a-Toc in SDS micelles exhibited oxygen uptake after the addition of a-Toc. The typical ESR spectrum of the a-To" radical was observed from the mixture. They attributed the rapid oxidation to decomposition of linoleate hydroperoxides, resulting in the formation of linoleate oxy radicals which initiated reactions on the lipid in the high concentration of the micellar micro-environment. Niki and coworkers reported pro-oxidant activity of a-Toc when it was added with metal ions, Fe3+25i Qj. jjj (jjg oxidation of phosphatidyl choline liposomes. a-Toc was found... 

Reactive aldehydes derived from lipid peroxidation, which are able to bind to several amino acid residues, are also capable of generating novel amino acid oxidation products. By means of specific polyclonal or monoclonal antibodies, the occurrence of malonaldehyde (MDA) and 4-hydroxynonenal (4-HNE) bound to cellular protein has been shown. Lysine modification by lipid peroxidation products (linoleic hydroperoxide) can yield neo-antigenic determinants such as N-c-hexanoyl lysine. Both histidine and lysine are nucleophilic amino acids and therefore vulnerable to modification by lipid peroxidation-derived electrophiles, such as 2-alkenals, 4-hydroxy-2-alkenals, and ketoaldehydes, derived from lipid peroxidation. Histidine shows specific reactivity toward 2-alkenals and 4-hydroxy-2-alkenals, whereas lysine is an ubiquitous target of aldehydes, generating various types of adducts. Covalent binding of reactive aldehydes to histidine and lysine is associated with the appearance of carbonyl reactivity and antigenicity of proteins [125]. 

Fig. 7. Oxidation of LDL phospholipids in the generation of minimally modified LDL. Seeding molecules like HPETE, HPODE, and cholesteryl linoleate hydroperoxide (CE-OOH) are proposed to trigger the oxidation of l-palmitoyl-2-arachidonoyl phosphatidylcholine in LDL, leading to the generation of three oxidized phosphatidylcholine species that confer atherogenic activity to minimally modified LDL. 12-LO, 12-lipoxygenase. Adapted from Ref. [28]. Reproduced with permission from the publisher.

Substrate for oxidation Cholesterol linoleate hydroperoxide as a pro-oxidant... 

During a study, there has been evaluated the effect of supplementation with a low dose of co-3, obtained by olive oil, on the oxidative modification of low density lipoprotein (LDL) in a group of healthy volunteers, for 16 weeks. Oxidative modification of LDL was assessed measuring the concentrations of free cholesterol, cholesteryl esters and cholesteryl linoleate hydroperoxide in LDL, following copper-induced lipid peroxidation for 0, 2, 3 and 4 h. LDL eicosapentaenoic acid and docosahexaenoic acid compositions were significantly lower in the group treated with )-3 olive oil than the group treated with w-3 fish oil. 

Tsai, W. G. Gass, A. E. G. Ferrocene-modified horseradish-peroxidase enzyme electrodes—a kinetic-study on reactions with hydrogen-peroxide and linoleic hydroperoxide. Analyst 1995, 120, 2249—2254. 

Makinen, E.M. and Hopia, A.I. 2000. Effects of a-tocopherol and ascorbyl pahnitate on the isomerization and decomposition of methyl linoleate hydroperoxides. Lipids, 35(11), 1215. 

Chen, J.H. and Schanus, E.G. The inhibitory effect of water on the Co and Cu catalyzed decomposition of methyl linoleate hydroperoxides. Lipids, 27, 234-239. 1992. 

Oarada, M., Kurita, N., Miyaji, M., and Terao, K. (1991) Depression of Phagocytic Activity of Human Polymorphonuclear Leukocytes by Methyl Linoleate Hydroperoxides, J. Nutr Sci. Vitaminol. 37, 625-628. 

Piazza, G.J., T.A. FogUa, andA. Nunez, Enantioselective Conversion of Linoleate Hydroperoxide to an a,P-Epoxy Alcohol by Niobium Ethoxide, J. Am. Oil Chem. Soc. 75 939-943 (1998). 

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