Hydroperoxide formation during autoxidation of conjugated linoleic acid methyl ester

Citation
Ti. Hamalainen et al., Hydroperoxide formation during autoxidation of conjugated linoleic acid methyl ester, EUR J LIPID, 103(9), 2001, pp. 588-593
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Agricultural Chemistry
Journal title
EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY
ISSN journal
1438-7697 → ACNP
Volume
103
Issue
9
Year of publication
2001
Pages
588 - 593
Database
ISI
SICI code
1438-7697(200109)103:9<588:HFDAOC>2.0.ZU;2-G
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 hydroperoxid e protons was confirmed by D2O exchange and by chemoselective reduction of the hydroperoxide groups into hydroxyl groups using NaBH4. These experiment s 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-octadecad ienoic acid methyl ester (9-OOH) and 13-hydroperoxy-9-cis,11-trans-octadeca dienoic acid methyl ester (13-OOH), which are formed during the autoxidatio n of methyl linoleate, were studied in detail to allow the comparison betwe en the two linoleate hydroperoxides and the CLA methyl ester hydroperoxides . The C-13 NMR spectra of samples enriched with one of the two linoleate hy droperoxide isomers were assigned using 2D NMR techniques, namely Correlate d Spectroscopy (COSY), gradient Heteronuclear Multiple Bond Correlation (gH MBC), 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 presenc e and absence of a-tocopherol and that the major isomers of CLA methyl este r hydroperoxides have a conjugated monohydroperoxydiene structure similar t o that in linoleate hydroperoxides.