A1 Refereed original research article in a scientific journal
Hydroperoxide formation during autoxidation of conjugated linoleic acid methyl ester
Authors: Hamalainen TI, Sundberg S, Makinen M, Kaltia S, Hase T, Hopia A
Publisher: WILEY-V C H VERLAG GMBH
Publication year: 2001
Journal:: European Journal of Lipid Science and Technology
Journal name in source: EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
Journal acronym: EUR J LIPID SCI TECH
Volume: 103
Issue: 9
First page : 588
Last page: 593
Number of pages: 6
ISSN: 1438-7697
DOI: https://doi.org/10.1002/1438-9312(200109)103:9<588::AID-EJLT5880>3.0.CO;2-L
Abstract
The aim of this study was to investigate whether hydroperoxides are formed in the autooxidation of conjugated linoleic acid (CLA) methyl ester both in the presence and sence of alpha -tocopherol: The existence of hydroperoxide protons was confirmed by D2O exchange and by chemoselective reduction of the hydroperoxide groups into hydroxyl groups using NaBH4. These experiments were followed by nuclear magnetic resonance (NMR) spectroscopy. The C-13 and H-1 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 C-13 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 C-13 and H-1 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 a-tocopherol and that the major isomers of CLA methyl ester hydroperoxides have a conjugated monohydroperoxydiene structure similar to that in linoleate hydroperoxides.
The aim of this study was to investigate whether hydroperoxides are formed in the autooxidation of conjugated linoleic acid (CLA) methyl ester both in the presence and sence of alpha -tocopherol: The existence of hydroperoxide protons was confirmed by D2O exchange and by chemoselective reduction of the hydroperoxide groups into hydroxyl groups using NaBH4. These experiments were followed by nuclear magnetic resonance (NMR) spectroscopy. The C-13 and H-1 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 C-13 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 C-13 and H-1 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 a-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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