Factors which affect the stability of highly unsaturated fatty acids. I. Differences in the oxidation of conjugated and nonconjugated linoleic acid

Allen, Robert R.; Jackson, A. H.; Kummerow, Fred A.

doi:10.1007/bf02749501

Cited by 27 publications

(23 citation statements)

References 17 publications

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“…The early literature reports that the autoxidation of conjugated fatty acids differs from that of the nonconjugated fatty acids and produces in an autocatalytic manner relatively low molecular weight polymeric peroxides (Allen et al 1949;Kern et al 1955Kern et al , 1956Privett 1959). The data supports oxygen-carbon rather than carbon-carbon polymerization, and indicates that appreciable amounts of isolated transunsaturation resides in the polymer fraction.…”

Section: Polymerization (Pathway A)mentioning

confidence: 92%

“…In addition, it has been established that the stability of CLA isomers decreases in the order trans,trans>cis,trans>cis,cis, which shows the stabilizing effect of a trans double bond (Yang et al 2000), as is seen for other fatty acids such as elaidic (18:1, 9t) and oleic acids (Lanser et al 1986). The literature on the susceptibility of CLA to autoxidation compared to other polyunsaturated fatty acids, however, is highly controversial; some studies suggest that CLA is less oxidizable than linoleic acid (Allen et al 1949;Fukumi & Ikeda 1970;Ha et al 1990), some others find an opposite trend (van den Berg et Chen et al 1997;Chen et al 2001;Yang et al 2000;Tsuzuki et al 2004) and yet others find similar susceptibility (Holman & Elmer 1947;Suzuki et al 2001). This controversy may perhaps be partly explained by the lack of studies performed with pure CLA isomers, the widely different conditions under which the oxidations are performed, and by problems in identification of adequate methods to monitor CLA autoxidation.…”

Section: Figure 11mentioning

confidence: 99%

“…It is well established by PV and oxygen consumption measurements (Allen et al 1949), by MS (Muizebelt et al 2000), and by HPSEC (Luna et al 2007) that the autoxidation profile of CLA differs from that of its nonconjugated counterpart. Peroxide products accumulate more slowly and only in small amounts compared to linoleic acid (Allen et al 1949;Suzuki et al 2004). CLA absorb less oxygen per mole of oxidized substrate than linoleic acid (Allen et al 1949;Tsuzuki et al 2004) and produces mainly polymeric products (Luna et al 2007).…”

Section: Figure 11mentioning

confidence: 99%

“…Peroxide products accumulate more slowly and only in small amounts compared to linoleic acid (Allen et al 1949;Suzuki et al 2004). CLA absorb less oxygen per mole of oxidized substrate than linoleic acid (Allen et al 1949;Tsuzuki et al 2004) and produces mainly polymeric products (Luna et al 2007). Because of these differences between the autoxidation of conjugated and nonconjugated diene fatty acids, the result should be interpreted with care.…”

Section: Figure 11mentioning

confidence: 99%

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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: Polymerization (Pathway A)mentioning

confidence: 92%

Section: Figure 11mentioning

confidence: 99%

Section: Figure 11mentioning

confidence: 99%

Section: Figure 11mentioning

confidence: 99%

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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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“…In the last study, Yanishlieva and Schiller [18] studied the oxidation of tristearin at 120 °C without and with 5% added sitosterol following peroxide value. As can be seen from the data of Allen et al [19], peroxide value measurements underestimate the degree of oxidation compared to oxygen consumption. Experimental rate data on the oxidation of substrates with or without additives (pro-and anti-oxidants), taken from these studies, are linearized and the exact mathematical forms of the rate equations are identified as explained vide supra and in previous papers [5][6][7][8].…”

Section: Methodsmentioning

confidence: 90%

On the kinetics of the autoxidation of fats: influence of pro‐oxidants, antioxidants and synergists

Brimberg¹,

Kamal‐Eldin

2003

Euro J Lipid Sci & Tech

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On the kinetics of the autoxidation of fats: influence of pro-oxidants, antioxidants and synergistsThe influence of minor amounts of pro-and anti-oxidants on the kinetics of the autoxidation of fat has been evaluated. The reaction rates of oxygen with the substrates were found to follow the same basic equation, hitherto established for pure substrates. There is evidence that the surface of the reaction vessel also acts as a reaction catalyst and its effect is proportional to the area of glass in contact with lipids. Oxidation is enhanced by trace metal ions as well as by surface-active compounds (e.g. hydroperoxides and sterols). Antioxidants such as α-tocopherol and butylated hydroxyanisole inhibit the oxidation by delaying the start of oxygen consumption (the induction period) while retarders like amino acids only decrease the rate of oxidation. Thus pro-and anti-oxidants affect either the start or the rate of oxygen consumption. The empirical formula dx/dt = k [O 2 ] (1-x/n) f´(t) was found applicable to the different stages of oxidation.

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Hydroperoxide formation during autoxidation of conjugated linoleic acid methyl ester

Hämäläinen

Sundberg

Mäkinen

et al. 2001

Eur. J. Lipid Sci. Technol.

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The aim of this study was to investigate whether hydroperoxides are formed in the autoxidation of conjugated linoleic acid (CLA) methyl ester both in the presence and absence of α-tocopherol. The existence of hydroperoxide protons was confirmed by D 2 O exchange and by chemoselective reduction of the hydroperoxide groups into hydroxyl groups using NaBH 4 . These experiments were followed by nuclear magnetic resonance (NMR) spectroscopy. The 13 C and 1 H NMR spectra of a mixture of 9-hydroperoxy-10-trans,12-cis-octadecadienoic acid methyl ester (9-OOH) and 13-hydroperoxy-9-cis,11-trans-octadecadienoic acid methyl ester (13-OOH), which are formed during the autoxidation of methyl linoleate, were studied in detail to allow the comparison between the two linoleate hydroperoxides and the CLA methyl ester hydroperoxides. The 13 C NMR spectra of samples enriched with one of the two linoleate hydroperoxide isomers were assigned using 2D NMR techniques, namely Correlated Spectroscopy (COSY), gradient Heteronuclear Multiple Bond Correlation (gHMBC), and gradient Heteronuclear Single Quantum Correlation (gHSQC). The 13 C and 1 H NMR experiments performed in this study show that hydroperoxides are formed during the autoxidation of CLA methyl ester both in the presence and absence of α-tocopherol and that the major isomers of CLA methyl ester hydroperoxides have a conjugated monohydroperoxydiene structure similar to that in linoleate hydroperoxides.

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Factors which affect the stability of highly unsaturated fatty acids. I. Differences in the oxidation of conjugated and nonconjugated linoleic acid

Cited by 27 publications

References 17 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

On the kinetics of the autoxidation of fats: influence of pro‐oxidants, antioxidants and synergists

Hydroperoxide formation during autoxidation of conjugated linoleic acid methyl ester

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