Investigation of Natural Phosphatidylcholine Sources: Separation and Identification by Liquid Chromatography−Electrospray Ionization−Tandem Mass Spectrometry (LC−ESI−MS²) of Molecular Species

Abstract

This study is a contribution to the exploration of natural phospholipid (PL) sources rich in long-chain polyunsaturated fatty acids (LC-PUFAs) with nutritional interest. Phosphatidylcholines (PCs) were purified from total lipid extracts of different food matrices, and their molecular species were separated and identified by liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS(2)). Fragmentation of lithiated adducts allowed for the identification of fatty acids linked to the glycerol backbone. Soy PC was particularly rich in species containing essential fatty acids, such as (18:2-18:2)PC (34.0%), (16:0-18:2)PC (20.8%), and (18:1-18:2)PC (16.3%). PC from animal sources (ox liver and egg yolk) contained major molecular species, such as (16:0-18:2)PC, (16:0-18:1)PC, (18:0-18:2)PC, or (18:0-18:1)PC. Finally, marine source (krill oil), which was particularly rich in (16:0-20:5)PC and (16:0-22:6)PC, appeared to be an interesting potential source for food supplementation with LC-PUFA-PLs, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA).

Combining liquid chromatography with ozone-induced dissociation for the separation and identification of phosphatidylcholine double bond isomers

“…The phosphatidylcholine composition of such extracts is known to be rich in PC 16:0_18:1, although the position(s) of unsaturation have not been fully elucidated [42,43].…”

“…While LC--MS/MS data has previously been used to assign the sum composition PC 34:1 in chicken egg yolk to the fatty acyl composition PC 16:0_18:1, those results provided no indication of the presence of double bond positional isomers [42]. Conversely, the LC--OzID data presented here demonstrate that the PC 34:1 lipid population in this extract is a mixture of the double bond positional isomers PC 16:0_18:1(n--9) and PC 16:0_18:1(n--7).…”

“…To assess the efficacy of this method for analyzing more complex lipids, the egg yolk extract was also interrogated for isomers of polyunsaturated phosphatidylcholines of sum composition PC and m/z 557, 573 (marked with p), representing neutral losses from the m/z 627 base peak that are consistent with the n--9 and n--6 double bond positions in the unsaturated acyl chain of PC 16:0_18:2(n--6,n--9) [25]. Both the PC 18:1_18:1 and PC 16:0_18:2 acyl chain compositions were previously assigned based on conventional tandem mass spectral analysis on egg yolk extract [42].…”

Two-Dimensional High Performance Liquid Chromatography-Mass Spectrometry for Phosphatidylcholine Analysis in Egg Yolk

“…The following acids belong to the omega-3 family: linolenic acid (ALA C18:3), eicosapentaenoic (EPA C20:5), docosapentaenoic (DPA C22:5), and docosahexaenoic (DHA C22:6). In omega-6 family, it may be found: linoleic acid (LA, C18:2) and arachidonic acid (AA, C20:4), respectively (Gładkowski et al, 2011;Le Grandois et al 2009). The ω-3 and ω-6 fatty acids should be included in the diet or taken as supplements, because they are not synthesized by mammals (Gładkowski et al, 2011).…”

Characterization of Phospholipid Molecular Species by Means of HPLC-Tandem Mass Spectrometry

“…Moreover, the increased commercial use of phospholipids as ingredients for functional food, baby-food and pet food, has lead to the development of specific analytical methods in order to separate and identify phospholipids (Le Grandois et al, 2009;Standal et al, 2010;Winther et al, 2010). For these reasons, the terms 'phospholipidomics' and 'phospholipidomic analysis' have been recently introduced to define the study of the phospholipid classes in their biological and natural environment in order to detect characteristic fingerprints of metabolic processes (Viola et al, 2007).…”