Global analysis of triacylglycerols including oxidized molecular species by reverse-phase high resolution LC/ESI-QTOF MS/MS

Recently, global analysis of triacylglycerols (TAGs) has become increasingly important in studies of abnormality of lipid metabolism in metabolic syndrome. TAGs consist of various molecular species, caused by their three fatty acyl chains with a large variety of carbon chain lengths and degrees of unsaturation. Therefore, most previously reported methods have been insufficient in global detection of TAGs including their structural isomers and TAGs with oxidized or odd number acyl carbon chain. Here we report an effective method for global analysis of TAG molecular species from complex lipid mixtures of mouse liver and white adipose tissue (WAT) using reverse-phased high resolution liquid chromatography (LC) coupled with electrospray ionization (ESI)-quadrapole/time of flight hybrid mass spectrometer (QTOF-MS). For effective profiling of TAG molecular species, sensitive two-dimensional (2D) maps were constructed and individual structures were correctly identified by the elution profile and MS/MS. As a result, TAGs including their structural isomers and TAGs with an odd number acyl carbon chain were separated and detected effectively on the 2D map as compared with conventional high performance LC. It was also found that our 2D profiling method was useful in searching characteristic molecular species globally. In mouse WAT, novel oxidized TAGs, which were mainly formed by hydroperoxidation of one of their linoleic acyl chains, were effectively detected in comparison with TAG molecular species of mouse liver.