Methyl linoleate hydroperoxide

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. 

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... 

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. 

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. 

Chan HWS and Levett G Autoxidation of methyl linoleate separation and analysis of isoneric mixtures of methyl linoleate hydroperoxides and methyl hydrojQ linoleates. LipldUi 12 99-104, 1977. 

Haila, K., Hopia, A. and Heinonen, M. Effect of j3-carotene and retinal on the formation of methyl linoleate hydroperoxides. Eur. J. Lipid Sci. Technol. 102, 31-36 (2000). 

Dimeric compounds are formed during the autoxidation of methyl linoleate and linoleate hydroperoxides under ambient conditions. Dimers formed from methyl linoleate hydroperoxides are composed of unsaturated fatty esters cross-linked through either peroxide or ether linkages and containing hydroperoxy, hydroxy or oxo substituents (Figure 4.6). 

Peroxy-linked dimers are also formed from linoleate hydroperoxides in the presence of free radical initiators and copper palmitate, and carbon-carbon linked dimers in the presence of copper catalysts. Decomposition of methyl linoleate hydroperoxides at 210°C under nitrogen produces mainly carbon-carbon linked dimers (82%), monomers with loss of diene conjugation, volatile compounds (4-5%) and water. The resulting dimers contain carbonyl and hydroxyl groups and double bonds scattered between carbon 8 and carbon 10. Linoleate hydroperoxides can dimerize by one of the termination reactions discussed in Chapter 1. The termination reactions involving combination of alkyl, alkoxyl, or peroxyl radical intermediates produce dimers with carbon-carbon, carbon ether, or peroxy links. The carbon-carbon and carbon-oxygen linked dimers are favored at elevated temperatures and the peroxy-linked dimers at ambient temperatures. The peroxy-linked dimers may also decompose to the ether-linked and carbon-carbon linked dimers via the corresponding alkyl and alkoxyl radical intermediates. 

Figure 4.6. Dimers from methyl linoleate hydroperoxides.

Figure 4.20. Homolytic-heterolytic mechanism for the decomposition of methyl linoleate hydroperoxides (Frankel et al, 1984). With permission of AOCS Press.

Analytical conditions The polar hydroperoxides were first separated from non-polar material by solid-phase extraction on anunonium columns, followed by reversed phase HPLC on C-18 columns using either methanol 2-propanaol (90 10, v/v) or methanol-2-propanol dichloromethane (80 10 10, v/v). The post-column CL reagent contained isoluminol and microperoxidase in borate buffer (pH 10)-methanol (30 70, v/v). Methyl linoleate hydroperoxides were used as external standards for quantification by CL and UV detectors, and 1,3-diolein by ELS detector. 

Lingnert and Eriksson (1981), (2)Eicher(1981), (3) Kim and Harris (1989)(4) Alaizelol. (1999), (5) Mastrocola and Munari (2000), (Q ling and Kitts (2002), (7) Dittrich et al. (2003). Abbreviations PV, peroxide value MRP, Maillard reaction products BSA, bovine serum albumin MeLo-OOH, methyl linoleate hydroperoxides TEARS, thiobarbituric reactive substances ABAP, 2,2 -azo-bis(2-amidinopropane)dichloride DPPH, l,l-diphenyl-2-picrylhydrazyl LDL, low-density lipoproteins CD, conjugated dienes. 

Chan, H.W.-S., Prescott, F.A.A., and Swoboda, P.A.T. (1976) Thermal Decomposition of Individual Positional Isomers of Methyl Linoleate Hydroperoxide Evidence of Carbon-Oxygen Bond Scission, J. Am. Oil Chem. Soc. 53, 572-576. 

Pure fatty acid hydroperoxides are very toxic to experimental animals when administered intravenously (i.v.) but not oraUy (Horgan et al., 1957 Olcott and Dolev, 1963 Findlay et al., 1970). Cortesi and Privett (1972) have shown that the 24-h lethal i.v. dose of a high purity preparation of methyl linoleate hydroperoxides in adult male rats was approximately 0.07 mmol/100 g body weight, and that the major effect of injected linoleate hydroperoxides was on the lungs. Also, vitamin E deficiency symptoms such as encephalomalacia in chicks (Nishida et al., 1960), and creatinuria and erythrocyte hemolysis in rabbits (Kokatnur et al., 1966) have been observed in animals infused with methyl linoleate hydroperoxides. 

Many secondary oxidation products of fatty acids have been shown to be more toxic to experimental animals. This is partly due to the fact that the low molecular weight products have shorter carbon chain lengths, and are more easily absorbed into the intestinal wall than lipid hydroperoxides or their polymeric materials. Oarada et al. (1986), for example, have shown that over 73% of radioactivity was found in the urine and CO2 of rats 12 h after receiving " C-labeled low molecular compounds, compared to less than 25% for methyl linoleate hydroperoxides and the polymeric fraction. 

Components of oxidized fats and oils may also accelerate the turnover of vitamin E and increase the susceptibility of the red cells to hemolytic stress. Alkenal, hydroxylalkenal and hydroperoxyalkenal, for example, have been shown to be more potent than methyl linoleate hydroperoxide in inducing hemolysis (Yoshioka and Kaneda, 1972, 1974). 

Bergan, J.G. and Draper, H.H. (1970) Absorption and metabolism of l- C-methyl linoleate hydroperoxide. Lipids 5, 976-982. 

Glavind, J. and Sylven, C. (1970) Intestinal absorption and lymphatic transport of methyl linoleate hydroperoxide and hydroxyoctadecadienoate in the rat. Acta Chem. Scand. 24, 3723-3728. 

Oarada, M., Miyazawa, T. and Kaneda, T. (1986) Distribution of " C after oral administration of [U- X] labeled methyl linoleate hydroperoxide and their secondary products in rats. Lipids 21, 150-154. 

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