144. The course of autoxidation reactions in polyisoprenes and allied compounds. Part VII. Rearrangement of double bonds during autoxidation

Farmer, Ernest Harold; Koch, H.; Sutton, Donald A.

doi:10.1039/jr9430000541

Cited by 138 publications

(48 citation statements)

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“…Hydroperoxides were identified as oxidation products of methyl oleate and methyl linoleate in the work of Farmer and co-workers (Farmer et al 1943;Bolland & Koch 1945). These studies led to the development of an autoxidation mechanism for monounsaturated and nonconjugated polyunsaturated fatty acids, also known as Farmer's hydroperoxide theory, which replaced the previous cyclic peroxide and ethylene oxide theories (reviewed in Swern 1961).…”

Section: Autoxidation Of Monoene and Nonconjugated Diene Fatty Acidsmentioning

confidence: 99%

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α‐Tocopherol: The Hydroperoxide Pathway

Pajunen

Johansson

Hase

et al. 2008

Lipids

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The autoxidation of conjugated linoleic acid (CLA) is poorly understood in spite of increasing interest in the beneficial biological properties of CLA and growing consumption of CLA-rich foods. In this thesis, the autoxidation reactions of the two major CLA isomers, 9-cis,11-transoctadecadienoic acid and 10-trans,12-cis-octadecadienoic acid, are investigated. The results contribute to an understanding of the early stages of the autoxidation of CLA methyl ester, and provide for the first time a means of producing and separating intact CLA methyl ester hydroperoxides as well as basic knowledge on lipid hydroperoxides and their hydroxy derivatives.Conjugated diene allylic monohydroperoxides were discovered as primary autoxidation products formed during autoxidation of CLA methyl esters in the presence and absence oftocopherol. This established that one of the autoxidation pathways of CLA methyl ester is the hydroperoxide pathway.Hydroperoxides were produced from the two major CLA methyl esters by taking advantage of the effect of -tocopherol to promote hydroperoxide formation. The hydroperoxides were analysed and separated first as methyl hydroxyoctadecadienoates and then as intact hydroperoxides by HPLC. The isolated products were characterized by UV, GC-MS, and NMR techniques. In the presence of a high amount of -tocopherol, the autoxidation of CLA methyl ester yields six kinetically-controlled conjugated diene monohydroperoxides and is diastereoselective in favour of one particular geometric isomer as a pair of enantiomers. The primary autoxidation products produced from the two major CLA isomers include new positional isomers of conjugated diene monohydroperoxides, the 8-, 10-, 12-, and 14-hydroperoxyoctadecadienoates. Furthermore, two of these new positional isomers have an unusual structure for a cis,trans lipid hydroperoxide where the allylic methine carbon is adjacent to the cis instead of the usual trans double bond.The 1 H and 13 C NMR spectra of nine isomeric methyl hydroxyoctadecadienoates and of ten isomeric methyl hydroperoxyoctadecadienoates including the unusual cis,trans hydroperoxides, i.e. Me 8-OOH-9c,11t and Me 14-OOH-10t,12c, were fully assigned with the aid of 2D NMR spectroscopy. The assigned NMR data enabled determination of the effects of the hydroxyl and hydroperoxyl groups on the carbon chemical shifts of CLA isomers, identification of diagnostic signals, and determination of chemical shift differences of the olefinic resonances that may help with the assignment of structure to as yet unknown lipid hydroperoxides either as hydroxy derivatives or as intact hydroperoxides.A mechanism for the hydroperoxide pathway of CLA autoxidation in the presence of a high amount of -tocopherol was proposed based on the characterized primary products, their relative distribution, and theoretical calculations. This is an important step forward in CLA research, where exact mechanisms for the autoxidation of CLA have not been presented before. Knowledge of these hydroperoxide formation steps is of cr...

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Section: Autoxidation Of Monoene and Nonconjugated Diene Fatty Acidsmentioning

confidence: 99%

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α‐Tocopherol: The Hydroperoxide Pathway

Pajunen

Johansson

Hase

et al. 2008

Lipids

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“…With unsaturated fats, susceptibility to autoxidation depends on the availability of allylic hydrogens for reactions with peroxy radicals. [4] Valence bond structure (A) may be represented as a hybrid (B) with a partial free radical at each end of the allylic system. Reaction of oxygen occurs at end carbon positions of the allylic system to produce a mixture of isomeric HP: [5] The most important termination process for secondary peroxy radicals at room temperature is that proposed by Russel (12) and involves a tetraoxide intermediate to produce a ketone, an alcohol, and oxygen (Reaction 6).…”

mentioning

confidence: 99%

A kinetic study on the autoxidation of sunflowerseed oil

Topallar

Bayrak

İşcan

1997

J Americ Oil Chem Soc

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Unhydrogenated and hydrogenated sunflowerseed oils were exposed to the autoxidation process by sunlight under atmospheric conditions. Experiments were carried out in equal-sized glass, PET (polyethylene terephthalate) polymer, and metal (covered by tin) containers. The reaction time was 30 d, and the reaction course was observed by determining weight changes and peroxide values (PV) of the oil samples at the same time within 2-d intervals. The logarithm of the PV was plotted against time, and straight lines were obtained from the 4th or 6th d. The autoxidation reaction constants were obtained for each oil in each container. When comparing the reaction constants, the unhydrogenated oils autoxidize easily, and the autoxidation reaction occurs faster in sunlight in glass than in the PET polymer container and much faster than in the darkness of the metal container.

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“…As reported in earlier studies, ROS cause oxidative damage to proteins such as Cu,Zn-superoxide dismutase and collagen, and can also be a causal agent of lipid peroxidation in cell membranes (Farmer et al, 1943;Greenwald and Moy, 1979;Curran et al, 1984;Ookawara et al, 1992;Halliwell and Gutteridge, 1999). It has been suggested that ROS are capable of degrading glycosaminoglycans, which are important components of extracellular matrices, thus leading to an impairment of proteoglycan functions (Moseley et al, 1995(Moseley et al, , 1997.…”

Section: Introductionmentioning

confidence: 96%

Modification of oligosaccharides by reactive oxygen species decreases sialyl lewis x-mediated cell adhesion

Eguchi¹,

Ikeda²,

Ookawara³

et al. 2005

Glycobiology

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144. The course of autoxidation reactions in polyisoprenes and allied compounds. Part VII. Rearrangement of double bonds during autoxidation

Cited by 138 publications

References 0 publications

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α‐Tocopherol: The Hydroperoxide Pathway

Autoxidation of Conjugated Linoleic Acid Methyl Ester in the Presence of α‐Tocopherol: The Hydroperoxide Pathway

A kinetic study on the autoxidation of sunflowerseed oil

Modification of oligosaccharides by reactive oxygen species decreases sialyl lewis x-mediated cell adhesion

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