Autoxidation of methyl linoleate: identification of the bis-allylic 11-hydroperoxide.
Based on the understanding of lipid peroxidation as a free radical chain reaction, over 50 yr ago the three primary products of linoleic acid autoxidation were predicted to be the 9-, 11-, and 13-hydroperoxides. The 9- and 13-hydroperoxides were found at the time, but formation of 11-hydroperoxylinoleate or any other bis-allylic fatty acid hydroperoxide has not been reported heretofore as a product of lipid peroxidation reactions. In vitamin E-controlled autoxidation of methyl linoleate, the 11-hydroperoxy derivative was identified as the next most prominent primary peroxidation product after the 9- and 13-hydroperoxides. It was present in approximately 5-10% of the abundance of the 9- or 13-hydroperoxide. The structures of 1l-hydroperoxylinoleate and its 11-hydroxy derivative were established by high-pressure liquid chromatography, ultraviolet spectroscopy, gas chromatography mass spectroscopy, and 1H nuclear magnetic resonance spectroscopy. The 11-hydroperoxide was not detectable in the absence of (alpha-tocopherol, indicating that efficient trapping of the 11-peroxyl radical as the hydroperoxide is critical to permitting its accumulation.
Brash
A R
AR
Department of Pharmacology, Vanderhilt University, Nashville, Tennessee 37232-6602, USA. alan.brash@mcmail.vanderbilt.edu
D002851:Chromatography, High Pressure Liquid; D005609:Free Radicals / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry; D008041:Linoleic Acids / Q000378:metabolism*; D015227:Lipid Peroxidation; D008054:Lipid Peroxides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D014810:Vitamin E / Q000378:metabolism
D005609:Free Radicals; D008041:Linoleic Acids; D008054:Lipid Peroxides; D014810:Vitamin E; C005575:methyl linoleate; D010100:Oxygen