Formation of triacylglycerol core aldehydes during rapid oxidation of corn and sunflower oils with tert‐butyl hydroperoxide/Fe2

• Published in: Lipids 2002-01, Vol.37 (1), p.81-94
• Main Authors: Sjövall, Olli, Kuksis, Arnis, Kallio, Heikki
• Format: Article
• Language: English
• Subjects: Aldehydes; Aldehydes - chemical synthesis; Aldehydes - chemistry; Chromatography; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Corn; Corn Oil - chemistry; Esters; Ionization; Iron; Liquid chromatography; Mass spectrometry; Molecular weight; Oils & fats; Oxidation; Oxidation-Reduction; Peroxidation; Plant Oils - chemistry; Spectrometry, Mass, Electrospray Ionization; Sunflower Oil; tert-Butylhydroperoxide; Thin layer chromatography; Triglycerides - chemical synthesis; Triglycerides - chemistry; Vegetable oils
• ISSN: 0024-4201; 1558-9307
• DOI: 10.1007/s11745-002-0867-5

The lipid ester core aldehydes formed during a rapid oxidation (7.8 M tert‐butyl hydroperoxide, 90 min at 37°C) of the triacylglycerols of purified corn and sunflower oils were isolated as dinitrophenylhydrazones by preparative thin‐layer chromatography and identified by reversed‐phase high‐performance liquid chromatography with on‐line electrospray ionization mass spectrometry and by reference to standards. A total of 113 species of triacylglycerol core aldehydes were specifically identified, accounting for 32–53% of the 2,4‐dinitrophenylhydrazine (DNPH)‐reactive material of high molecular weight representing 25–33% of the total oxidation products. The major core aldehyde species (50–60% of total triacylglycerol core aldehydes) were the mono(9‐oxo)nonanoyl‐ and mono(12‐oxo)‐9,10‐epoxy dodecenoyl‐ or (12‐oxo)‐9‐hydroxy‐10,11‐dodecenoyl‐diacylglycerols. A significant proportion of the total (9‐oxo)nonanoyl and epoxidized (12‐oxo)‐9,10‐dodecenoyl core aldehydes was found in complex combinations with hydroperoxy or hydroxy fatty acyl groups (6–10% of total triacylglycerol core aldehydes). Identified were also di(9‐oxo)nonanoylmonoacylglycerols (0.5% of total) and tri(9‐oxo)nonanoylglycerols (trace). The identification of the oxoacylglycerols was consistent with the products anticipated from tert‐butyl hydroperoxide oxidation of the major species of corn and sunflower oil triacylglycerols (mainly linoleoyl esters). However, the anticipated (13‐oxo)‐9,11‐tridecadienoyl aldehyde‐containing acylglycerols were absent because of further oxidation of the dienoic core aldehyde. A significant proportion of the unsaturated triacylglycerol core aldehydes contained tert‐butyl groups linked to the unsaturated fatty chains via peroxide bridges (2–9%). The study demonstrates that rapid peroxidation with tert‐butyl hydroperoxide consitutes an effective method for enriching natural oils and fats in triacylglycerol core aldehydes for biochemical and metabolic testing.