Changes in fatty acid composition during preparative thin-layer chromatography

Omega-3 polyunsaturated fatty acid blood biomarkers increase linearly in men and women after tightly controlled intakes of 0.25, 0.5, and 1 g/d of EPA + DHA

Blood levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been related to coronary heart disease risk. Understanding the response of EPA + DHA in blood to dietary intake of EPA + DHA would facilitate the use of blood measures as markers of adherence and enable the development of dietary recommendations. The objective of this study is examine the blood response to intakes of EPA + DHA ≤1 g/d with an intervention designed for dietary adherence. It was hypothesized this relationship would be linear and that intakes of EPA + DHA <1 g/d would result in blood levels below those associated with the highest level of protection for cardiovascular events. Background EPA + DHA intake of men and women (n = 20) was determined by food frequency questionnaire and adherence was monitored by weekly fingertip blood sampling for fatty acid determinations. Participants consumed nutraceuticals to achieve intakes of 0.25 g/d and 0.5 g/d EPA + DHA for successive four-week periods. A subgroup (n = 5) had intakes of 1.0 g/d EPA + DHA for an additional 4 weeks. Fatty acid composition of whole blood, erythrocytes, and plasma phospholipids were determined at each time point. Blood levels of EPA and DHA increased linearly in these pools. A comprehensive review of the literature was used to verify the blood-intake relationship. Blood levels of long chain omega-3 polyunsaturated fatty acids reached blood levels associated with the highest levels of primary cardiac arrest reduction and sudden cardiac death risk only with intakes of 1.0 g/d of EPA + DHA. The blood biomarker response to intakes of EPA + DHA ≤1 g/d is linear in a small but highly adherent study sample and this information can assist in determining adherence in clinical studies and help identify dietary intake targets from associations between blood and disease.

Digestion of butyrate glycerides by pancreatic lipase

The racemic triglycerides, glyceryl-1-palmitate-2,3-dibutyrate (PBB), glyceryl-1-butyrate-2,3-dipalmitate (PPB), glyceryl-2-butyrate-1,3-dipalmitate (PBP), and the diglyceride, racemic glyceryl-1-palmitate-3-butyrate (P-B) were synthesized and digested with pancreatic lipase. Each triglyceride was mixed with equimolar amounts of triolein (OOO) prior to incubation.The following order of digestion rates was observed: PBB>PPB>PBP>P-B. There was no evidence for short-chain fatty acid specificity; however the triglycerides containing butyric acid were hydrolyzed more rapidly than OOO. Based upon the fatty acid composition of partial glycerides, digestion of butyrate glycerides was not a simple phenomenon. For example, in the digestion of PBB, butyric acid accumulated faster than palmitic acid in the diglycerides, and monobutyrin was found to accumulate when the diglyceride, P-B, was digested. As evidenced by the fatty acid composition of the monoglycerides, positional specificity of pancreatic lipase was always maintained.

Triglyceride analysis by consecutive liquid-liquid partition and gas-liquid chromatography.Ephedra nevadensis seed fat

The triglyceride composition ofEphedra nevadensis seed fat, which contains 16 different fatty acids, has been analyzed by a combination of liquid-liquid partition and gas-liquid chromatography. Triglycerides were first separated by liquid-liquid partition chromatography. The recovered fractions were then analyzed by gas-liquid chromatography to determine the molecular weights of the triglycerides present. Consecutive separation by these two techniques resolved this complex seed fat into 30 different triglyceride groups.A method for preparative liquid-liquid partition chromatography of triglycerides is described in detail. Highly unsaturated triglyceride mixtures are easily resolved on the basis of "partition number" by using a hexadecane/nitroethane partition system.

High-performance liquid chromatographic study of the regulation of phospholipid metabolism in cultured adrenocortical cells

A rapid high-performance liquid chromatographic (HPLC) method for the separation of phospholipids was developed for minute samples of total lipids (ca. 200 micrograms). The method was applied to the study of the phospholipid metabolism in adrenocortical cell cultures. A complete separation of the different cellular phospholipid classes was achieved in 40 min. Good resolution of the phospholipid peaks was obtained, which allowed the collection of each individual class of phospholipids for further analysis of radioactivity and fatty acid composition by gas chromatography. When cells were incubated with [U-14C]glycerol or [U-14C]palmitate the bulk of the radioactivity was found in cellular phosphatidylcholines. Exogenous phospholipids were incorporated into cellular lipids to a large extent, however without an increase in the cellular phospholipid content. 12-O-Tetradecanoyl-phorbol-13-acetate induced a 20% increase in the polyunsaturated fatty acid content of the cellular phosphatidylethanolamines, but no change was detected in the cellular phosphatidylcholines. The developed method is well-suited to the study of the phospholipid metabolism in adrenocortical cells where the phospholipid metabolism is closely linked to the specialized functions of the cells.

Simultaneous determination of amounts of major phospholipid classes and their fatty acid composition in erythrocyte membranes using high-performance liquid chromatography and gas chromatography

A method for the simultaneous determination of amounts of major phospholipid classes and their fatty acid composition in erythrocyte membranes is described. The method consists in extraction of phospholipids from erythrocyte membranes, separation of phospholipid classes by high-performance liquid chromatography, methylation of phospholipids and determination of phospholipid-bound fatty acids by capillary gas chromatography. The amounts of phospholipid classes are calculated from the total weight of phospholipid-bound fatty acids and their average molecular weights. The method was applied to erythrocytes from rats. The results show that the method is reproducible and is useful for the determination of amounts of phospholipid classes and their fatty acid composition in small blood samples.

31P-NMR assay of phosphatidylcholine and phosphatidylethanolamine in AL721

A 31P-NMR based method has been developed for the assay of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in AL721. The assay is based on the comparison of NMR signal intensities of the phosphatidyl moiety of PC and PE to the signal of triphenylphosphate (TPP), the internal standard. The assay is specific and reliable for the quantitation of phospholipid mixtures. Its uncertainty, due primarily to low intensity of 31P signals, was estimated at less than 6%.

1H-NMR assay of phosphatidylcholine and phosphatidylethanolamine in AL721

A 1H-NMR based method has been developed for the assay of phosphatidylcholine (PC), and phosphatidylethanolamine (PE) in AL721. The assay was based on the comparison of NMR signal intensities of the choline and the ethanolamine moiety of PC and PE, respectively, to the signal of imidazole, the internal standard. The assay was reliable and more accurate than the commonly used LC or TLC methods. The uncertainty, due primarily to signal intensities, of the 1H-NMR method was estimated at less than 3%.