NMR properties of conjugated linoleic acid (CLA) methyl ester hydroperoxides

: Pajunen TI, Koskela H, Hase T, Hopia A

Publisher: ELSEVIER IRELAND LTD

: 2008

Chemistry and Physics of Lipids

CHEMISTRY AND PHYSICS OF LIPIDS

: CHEM PHYS LIPIDS

: 154

: 2

: 105

: 114

: 10

: 0009-3084

DOI: https://doi.org/10.1016/j.chemphyslip.2008.05.001

NMR data on lipid hydroperoxides is scarce. In this study, hydroperoxides were produced from methyl 9-cis, 11-trans-octadecadienoate and from methyl 10-trans,12-cis-octadecadienoate by autoxidation in the presence of 20% of alpha-tocopherol. Ten different hydroperoxides were isolated from the autoxidation mixtures of the two conjugated linoleic acid (CLA) methyl esters by SPE and HPLC. The assignment of the H-1 and C-13 NMR spectra of these hydroperoxides was accomplished by 2D NMR experiments and by spectral simulations. Substitution of a hydroperoxyl group at the allylic position in CLA methyl esters induced a 53.93 ppm downfield shift on the hydroperoxyl-bearing carbon resonance. The effects on the olefinic alpha, beta, gamma, and delta carbon resonances were -3.45, +4.96, -1.22, and +4.42 ppm, respectively. Furthermore, the solvent effects of deuterochloroform, deuteroacetone, and deuterobenzene on the C-13 resonances of the hydroperoxides suggest that deuterochloroform is the appropriate solvent for C-13 NMR studies on mixtures of lipid hydroperoxides. (C) 2008 Elsevier Ireland Ltd. All rights reserved.