Targeting Modified Lipids during Routine Lipidomics Analysis using HILIC and C30 Reverse Phase Liquid Chromatography coupled to Mass Spectrometry

Abstract

Lipids are important biomolecules in all biological systems and serve numerous essential cellular functions. The global analysis of complex lipids is very challenging due to the extreme diversity in lipid structures. Variation in linkages and positions of fatty acyl chain(s) on the lipid backbone, functional group modification, occurrence of the molecular species as isomers or isobars are among some of the greatest challenges to resolve in lipidomics. In this work, we describe a routine analytical approach combining two liquid chromatography platforms: hydrophilic interaction (HILIC) and C30 reversed-phase chromatography (C30RP) coupled to high resolution mass spectrometry (HRMS) as complementary high throughput platforms to analyze complex lipid mixtures. Vascular plants (kale leaves and corn roots), rat brain and soil microbes were used as proxies to evaluate the efficiency of the enhanced approach to resolve traditional, as well as, modified lipids during routine lipidomics analysis. We report for the first time, the observation of a modified class of acylphosphatidylglycerol (acylPG) in corn roots by HILIC, and further resolution of the isomers using C30RP chromatography. We also used this approach to demonstrate the presence of high levels of N-monomethyl phosphatidylethanolamine (MMPE) in soil microbes, as well as to determine the regioisomers of lysophospholipids in kale leaves. Additionally, neutral lipids were demonstrated using C30RP chromatography in positive ion mode to resolve triacylglycerol isomers in rat brain. The work presented here demonstrates how the enhanced approach can more routinely permit novel biomarker discovery, or lipid metabolism in a wide range of biological samples.

Lipidomic Profiling of the Olive (Olea europaea L.) Fruit towards Its Valorisation as a Functional Food: In-Depth Identification of Triacylglycerols and Polar Lipids in Portuguese Olives

“…In this work, the analysis of TAGs was achieved by using C 30 in LC-MS, which is nowadays considered as one of the best approaches for the screening of this type of lipids [22]. C 30 LC-MS has been used for TAG profiling in palm and canola oils, in which seventy molecular species were identified [23], and in biological specimens, such as rat plasma and liver [24].…”

Mass Spectrometry Data Repository Enhances Novel Metabolite Discoveries with Advances in Computational Metabolomics

“…In effect, the coverage of lipid classes was doubled by updating the computational mass spectrometry techniques and mass spectral libraries, and our reanalysis indicates the value of MS data repositories where the raw data could be utilized as a benchmark for new software programs and data-driven hypothesis generation. The lipidomics workflow is also executable with hydrophilic interaction chromatography (HILIC) [32] or supercritical fluid chromatography (SFC) [33], in which the molecules can be separated based on the specific chemical properties of each lipid class, enabling efficient exclusion of false-positive annotations from incorrect lipid classes. Ion mobility MS provides another diagnostic criterion, viz.…”

Use of Natural Antioxidants from Newfoundland Wild Berries to Improve the Shelf Life of Natural Herbal Soaps

“…The method used for lipid analysis is described in a previous publication by our group [26]. Briefly, unsaponified complex lipids (oils) extracted from natural soap were separated using an Accucore C30 column (150 × 2 mm I.D., particle size: 2.6 µm, pore diameter: 150 Å obtained from ThermoFisher Scientific, ON, Canada).…”