Chromatographic analysis of alkoxy-lipids

A simple and sensitive determination for plasmalogen lysophosphatidylethanolamine in rabbit platelets

Plasmalogen lysophosphatidylethanolamine (LPE) in rabbit platelets was quantitatively determined as glycero-3-phosphorylethanolamine (GPE) after treatment with 5% trichloroacetic acid at 20 degrees C for two hours. GPE was measured directly using a high performance liquid chromatography with monitoring the fluorescence of o-phthaldialdehyde/2-mercaptoethanol adducts. The assay was sensitive to 50 pmol of plasmalogen LPE and was linear over a 200-fold concentration range. While, 1-acyl LPE and phosphatidylethanolamine from bovine brain (containing about 50% plasmalogen) were hardly cleaved to GPE under the same conditions. These procedures were specific for plasmalogen LPE, and simpler and more sensitive in comparison with conventional analytical methods, e.g., two-dimensional thin layer chromatography with subsequent phosphorus assay. Employing the present method, plasmalogen LPE was found to increase rapidly and to decrease subsequently when rabbit platelets were stimulated by thrombin.

Quantification of plasmalogen, alkylacyl and diacyl glycerophospholipids by micro-thin-layer chromatography

A method for the determination of plasmalogen, alkylacyl and diacyl glycerophospholipids based on mild alkaline deacylation and acid hydrolysis of plasmalogens on plates with subsequent micro-thin-layer chromatography on silica gel is presented. It is effective in quantifying alkyl and alkenyl analogues of phosphatidylethanolamine and phosphatidylcholine at concentrations up to 0.1% (of the total of the forms in individual classes of phospholipids.

HPLC of plasmalogen-containing phosphatidylcholine under reverse-phase or argentation conditions

Two approaches to the high pressure liquid chromatography (HPLC) isolation of intact plasmalogens were investigated. The first used reversed-phase HPLC and sought to take advantage of subtle differences in the hydrophobicity of the alk-1-enyl chain from the acyl counterpart. On a C-18 column, bovine heart phosphatidylcholine (PC), which was 47% plasmalogen, was separated into a number of fractions that differed in their molecular species composition. One combination of fractions amounted to a 26% yield of PC enriched to 82% plasmalogen. The second approach sought to take advantage of the uniquely electron-rich functionality of the plasmalogens, the alk-1-enyl ether double bond, and its potential to coordinate with heavy metal ions. Specifically, bovine heart PC was applied to a cation-exchange type HPLC column in the silver ion mode. Although complete exchange of all the active sites of the column with silver ion led to complete retention of PC, partial activation with silver ion resulted in the separation of the PC into fractions, according to the degree of unsaturation. Plasmalogen-rich fractions eluted last and remained intact during the process. One combination of these fractions amounted to a 49% yield of PC enriched to 72% plasmalogen. Use of a cation-exchange system in the mercuric ion mode led to on-column hydrolysis of the plasmalogen; with palladium ion, the metallic species was stripped from the column by the eluting lipid.

Lipid composition and biosynthesis of human omental tissue

Two groups of five males each were selected for total lipid analyses of their omental tissue. One of these groups had been subjected to a severe caloric restriction and had undergone total weight reduction of about 20%. The other group served as control. Both of these groups of patients required elective surgical procedures during which it was possible to obtain small samples of omental tissue, adipose pad, and/or mesenteric tissue. Total lipid analyses were performed on all of the materials. A distinctive positional distribution of the acyl groups was maintained in the triglycerides of omental tissue for all the patients regardless of dietary state. Patients under caloric restriction showed a reduction in their total triglyceride content, a reduction in their content of unsaturated fatty acyl groups, and a relative increase in phospholipid content. The de novo lipid biosynthetic capacity of omental tissues, as determined by 1-[14C]-acetate incorporation, showed an inverse proportionality to the lipid content of the samples. Omental tissue is biosynthetically a very versatile material capable of yielding rapidly many types of fatty acids. This ability, among others, could account for the usefulness of omental tissue as a supporting base in many types of restorative surgery.