Neutral glycolipids of human and bovine milk

The neutral glycolipids of milk, a small fraction of the total lipids, are of potential biological importance. The simultaneous quantitation of the simple (less than five sugars) glycosphingolipids of human milk samples was achieved by high-pressure liquid chromatography. The samples, representing various stages of lactation, parity of the nursing child, and age of the mother, contained similar glycolipid patterns, but with varying individual glycolipid concentrations. The cerebrosides are major glycosphingolipids of human milk: the non-hydroxylated fatty acid (NFA)-containing species are present at 1.8 μM, and the hydroxylated and/or short-chain fatty acid-containing species (HFA) are present at 1.7 μM; NFA lactosylceramide is present at 931 nM. The cerebrosides appear to be primarily galactosylceramides (galactocerebrosides); glucosylceramides (glucocerebrosides) are a minor component. Globotriaosylceramide (Gb₃) is found at 50 nM and 73 nM for the NFA and HFA species, respectively, while globoside (Gb₄) is found at 45 nM and 46 nM for the NFA and HFA species. Bovine milk glycosphingolipids differ from those of human milk, with bovine milk containing mainly NFA glucosylceramide (8 μM) and NFA lactosylceramide (17 μM); bovine milk contains little Gb₃ or Gb₄. Based on a paper presented at the Symposium on Milk Lipids held at the AOCS Annual Meeting, Baltimore, MD, April 1990.     

Fatty acid distribution in the phospholipids ofFrancisella tularensis

Francisella tularensis, LVS (live vaccine strain) grown in a chemically defined medium was found to have a lipid content of 21% by dry weight. The two major phospholipids were identified as phosphatidylethanolamine (PE; 76%) and phosphatidylglycerol (PG; 24%) by thin layer chromatographic analysis, staining characteristics and quantitative chemical analyses of fatty acid, phosphate and glycerol constituents. PE contained a high proportion of 24∶0 fatty acid, with lesser amounts of 24∶1, 22∶0 and 10∶0. The major fatty acids of PG were 18∶1 and 22∶0. Hydroxy fatty acids, which are prominent components ofF. tularensis, were conspicuously lacking in these phospholipids; it is therefore concluded that hydroxy fatty acids are constituents of other structures of the organism.     

Fatty acids in phospholipids isolated from human red cells

Total lipids of packed erythrocytes from healthy men 22 to 25 years old were extracted with chloroform-methanol mixture. Phospholipid classes were separated from neutral lipids and pigments on a silicic acid column. Phosphatidyl inositol (PI) was freed of its contaminants phosphatidyl ethanolamine (PE) and phosphatidyl serine (PS) on an aluminum oxide column. Additional silicic acid columns with modified solvent systems were needed for complete separation of other overlapped phospholipid classes. The identification of phospholipids in each eluted fraction was accomplished by TLC, using the appropriate spray tests and reference compounds, and confirmed on each of the isolated phospholipids by IR spectrophotometry. The total content of phospholipids as determined by phosphorus analysis was found to be 2.63 mg/ml of packed cells. These phospholipids were found to have the following composition (in per cent of total phospholipid): PI, 2.3; PE, 13.4; ethanolamine plasmalogen (EP), 14.5; PS, 3.9; lecithin (L), 34.2; choline plasmalogen (CP), 1.4; sphingomyelin (Sph), 28.4 and lysolecithin (LL), 1.7. The fatty acid composition of each phospholipid was determined by GLC. The average number of double bonds per fatty acid in the isolated phospholipids was found to be as follows: PI, 1.5; PE, 1.9; EP, 3.6; PS, 2.1; L, 1.0; CP, 2.0; Sph, 0.2 and LL, 0.5. The positional distribution of fatty acids in both L and PE was ascertained by selective enzymatic hydrolysis with phospholipase A. Saturated fatty acids of L were esterified predominantly in the α′-position, whereas in PE only 63.9 mole per cent of the saturated fatty acids were found in this position. Presented in part at the AOCS Meeting in Los Angeles, April 1966. Dept. of Health, Education and Welfare, USPHS.     

Essential fatty acids in maternal diet and in rat milk phospholipids

The administrations of semisynthetic diets supplemented with oils and fats containing different levels of linoleic acids to lactating rats result in corresponding changes in the polyunsaturated fatty acids of triglycerides in the collected milk. Milk phospholipids show a quite different trend, polyunsaturated acids of the linoleic acid family being highest with low dietary linoleic acid supply, and vice versa, suggesting a control in the secretion of polyunsaturated fatty acids in milk.     

Fatty acid distribution in the bovine pre- and postpartum testis

Testes from fetuses, calves, bulls and recently castrated animals were analyzed for total lipids, lecithin, cephalin, triglycerides, diglycerides, cholesteryl esters and cholesterol. Total lipids increase somewhat with age, but in the castrated animal the increase is more marked. Phospholipid content increases with age, but decreases in the castrated animal. Cholesterol decreases and triglyceride increases after birth and in the castrated animal. Polyunsaturated acids increase with age in all lipid classes. Eicosatrienoic acid is more abundant in fetal testicular lipids than in testes removed after birth. In the castrated testis there is a general decrease in the unsaturated fatty acids. Acids of the ω6 family are the predominant polyunsaturated acids and increase somewhat with age in all lipids. The ω3 family of polyunsaturated acids appears mostly toward the end of fetal life and increases after birth. Acids of the linoleate family reach approximately 25% of total acids in most lipid classes at maturity whereas the ω3 acids range from 1 to 9%. Presented at the American Dairy Science Association Meeting, Lexington, Ky., June 1965.     

Determination of positional distribution of short-chain fatty acids in bovine milk fat on chiral columns

The positional distribution of acetic and butyric acids in bovine milk fat triacylglycerols was determined by chiral-phase high-performance liquid chromatography (HPLC) of the derived diacylglycerols. Enriched fractions of acetic and butyric acid-containing triacylglycerols were isolated by normal-phase thin-layer chromatography (TLC) from a molecular distillate of butter oil, and they were fully hydrogenated. Mixedsn-1,2(2,3)- andX-1,3-diacylglycerols of short- and long-chainlength, which were generated by partial Grignard degradation of the hydrogenated triacylglycerols, were isolated by borate-TLC. The enantiomericsn-1,2-andsn-2,3-diacylglycerols and theX-1,3-diacylglycerols as their 3,5-dinitrophenylurethanes were resolved by HPLC on chiral columns. Both acetic and butyric acids were exclusively associated with thesn- 2,3- andX-1,3-diacylglycerols of short and long chainlength. These results establish the presence of acetic and butyric acids in thesn-3-position of bovine milk fat triacylglycerols. Other short-and medium-chainlength acids were found in progressively increasing proportions also in thesn-1- andsn-2-positions.     

Studies on the glycolipids and phospholipids of immature soybeans

The lipid of immature soybeans was extracted with chloroform-methanol and fractions containing the glycolipids and phospholipids were separated by column chromatography. Phosphatidyl choline (PC), phosphatidyl ethanolamine (PE), phosphatidyl inositol (PI), phosphatidic acid (PA) phosphatidyl glycerol (PG), n-acyl phosphatidyl ethanolamine (APE) and sulfolipid (SL) were identified by thin layer chromatography (TLC). Sterol glucoside (SG), esterified sterol glucoside (ESG), digalactosyl diglyceride (DGDG) and cerebrosides (CE) were isolated by TLC and identified by color reactions, chemical degradation and spectral analysis.     

Positional distribution of fatty acids in the triglycerides of bovine milk fat with elevated levels of linoleic acid

A stereospecific distribution of fatty acids in bovine milk fat containing 15.5% linoleic acid has been compared with the distribution in bovine milk fat containing a normal level (1.8%) of linoleic acid. The positional distribution was obtained by the separate analysis of milk fat triglycerides of high, medium, and low molecular weight. The order of preference for linoleic acid in the high molecular weight triglycerides was position 3>position 2 >position 1. There was an accompanying altered distribution of myristic acid and palmitic acid in favor of position 1 at the expense of position 3. However, the proportions of myristic acid and palmitic acid in position 2, relative to positions 1 and 3 were identifical in the high molecular weight fractions of the two milk fats. The distribution of linoleic acid in the medium molecular weight triglycrides of linoleic-rich milk fat was position 1=position 2>position 3. This resulted in a change in the distribution of 18 carbon monounsaturated fatty acids in favor of position 2 at the expense of position 1, but the distribution of myristic acid and palmitic acid was virtually unaltered. The distribution of linoleic acid in the low molecular weight triglycerides was position 2>position 1>position 3. The amounts of myristic acid and palmitic acid in position 2 and of palmitic acid in position 1 decreased in the low molecular weight triglycerides of the milk fat containing elevated levels of linoleic acid. Changes in the distribution of fatty acids which were observed in the separate analysis of the high, medium, and low molecular weight triglycerides were not apparent when comparing the distribution in the total milk fats. For example, the distribution of myristic acid and palmitic acid appeared to be unchanged, while the distribution of 18 carbon monounsaturated fatty acids was slightly altered in favor of positions 2 and 3. Moreover, linoleic acid showed an almost equal preference for the three positions of the glycerol moiety in milk fat containing elevated levels of this fatty acid with some concentration at position 2.     

Studies of the phospholipids,glycolipids and sterols of wheat endosperm

The phospholipid-glycolipid mixture, isolated chromatographically from the “free” (hexane soluble) and “bound” (hexane insoluble, water-saturated butanol extractable) lipid of wheat endosperm, was fractionated by column and thinlayer silicic acid chromatography. The components were identified by hydrolysis followed by thin-layer or paper chromatography of the products. They included a sterol-containing glycolipid, hitherto unreported in wheat. The fatty acid and sterol compositions of the phospholipidglycolipid components were determined by gasliquid chromatography. Differences were found between varieties and between components. Contribution No. 14 of the Food Research Institute, Canada Dept. of Agriculture, Ottawa, Can. Presented at the AOCS Fall Meeting, Minneapolis, 1963.     

The role of neutral glycolipids and phospholipids in myxovirus-induced membrane fusion

Myxoviruses (influenza virus and paramyxovirus) enter host cells by two successive steps consisting of attachment and fusion between viral and cellular membranes. The initial attachment is known to occur through specific binding of the viruses with the neuraminic acid-containing receptors of cellular membranes. Evidence is presented here that, in the following step of membrane fusion, neutral glycolipids terminating in galactose and certain phospholipids (primarily lecithin and sphingomyelin) interact with the viral envelopes and that this interaction may be fundamental to the fusion process.     

Fatty acids of the milk and food of the platypus (Ornithorhynchus anatinus)

Platypus milk fat contains 98.5% triglyceride. Polyunsaturates (C18∶2–C22∶5) account for 29% of the triglyceride fatty acids in the milk fat and 32% of the total fatty acids in the lipid of the food of the platypus. Linoleate and arachidonate are the major ω6 polyunsaturates of both food and milk lipids. However, while the ω3 polyunsaturates linolenate and eicosapentaenoate are present in both food and milk, docosapentaenoate is present in meaningful amounts in milk only. It is suggested that with the exception of 22∶5ω3, the polyunsaturates in platypus milk originate in the diet.     

Terahertz absorption spectra of Fatty acids and their analogues

Absorption spectra in the terahertz (THz) region between 10 and 400 cm(-1) were measured for fatty acids and their analogues at room temperature. Saturated fatty acids such as palmitic and stearic acids had some sharp peaks, while unsaturated fatty acids such as oleic, linoleic and linolenic acids had two distinct peaks at 247 and 328 cm(-1). These peaks apparently derived from the carboxylic group because oleyl alcohol had no distinct peak. The THz absorption spectra of fatty acids may be affected by the crystalline as well as the chemical structure. The THz absorption spectra of oleic acid esters depended on ester types, although all oleic acid esters had some peaks due to the ester group. THz absorbance of fatty acids positively correlated with concentration. Based on these results, THz spectrometry may be a good analytical method for the non-destructive qualitative and quantitative evaluation of fatty acids and their analogues.     

Fatty acid derivatives and glycolipids in high-protein bakery products

High-protein bakery foods, particularly breads, are ideal for alleviating protein malnutrition in poverty areas of the world. Fortifying wheat flour with a high level of protein-rich additives like soy flour can, however, induce adverse effects upon dough properties and bread quality. Several fatty acid derivatives, including sucroesters, fatty esters of polyalkoxylated polyoglycosides, sodium or calcium stearoyl-2 lactylate, and ethoxylated monoglycerides and glycolipids, recently have been shown to improve effectively the baking performance of wheat flour fortified with soy flour. The nutritional benefits of high-protein breads are reported with results from feeding studies using the breads in diets of experimental rats. The possible mechanisms concerning the improving action of fatty acid derivatives are proposed and discussed. One of 12 papers presented in the symposium “Novel Uses of Agricultural Oils” at the AOCS Spring Meeting, New Orleans, April 1973. Contribution 825 from the Department of Grain Science and Industry, Kansas State University.     

Composition of the phospholipids and their fatty acids in the ROC-1 oligodendroglial cell line

ROC-1 cells are a hybrid of C−6 rat glioma and rat oligodendroglia cells. Biochemically these cells resemble the oligodendroglia parent, but their lipid composition is unknown. The phospholipid composition in mole % was: cardiolipin, 1.0; phosphatidylglycerol, 1.2; ethanolamine glycerophospholipids, 27.6; phosphatidylinositol, 5.8; lysophosphatidylethanolamine, 0.8; phosphatidylserine, 5.6; choline glycerophospholipids, 43.7; sphingomyelin, 13.7; phosphatidylinositol-4-monophosphate, 0.8; and lysophosphatidylcholine, 0.6. The choline and ethanolamine plasmalogens made up 7.2 and 18.4% of the total phospholipids, respectively. The phospholipid composition reflects that of both parental cells. The cells had moderate to high levels of 20∶3n−9 indicating n−6 series fatty acid deficiency. The phosphatidylinositol had very high 20∶3n−9 levels with a 20∶3n−9/20∶4n−6 ratio of 2.1 compared to 0.44 and 0.58 for ethanolamine glycerophospholipids (EtnGpl) and choline glycerophospholipids (ChoGpl) respectively. The saturated/polyenoic fatty acid ratios were 0.40 for EtnGpl, 3.38 for ChoGpl and 1.48 for phosphatidylinositol.     

Application of phospholipids extracted from bovine milk to the reconstitution of cream using butter oil

Phospholipid (PL) extracted from bovine milk was tested for its emulsifying properties in conjunction with the reconstitution of cream using butter oil. PL from bovine milk dispersed in the oil phase was found to stabilize the cream, whereas PL extracted from soybean oil was found to solidify the cream. Different PL species purified from bovine milk PL were tested for their emulsifying properties. PC from bovine milk dispersed in butter oil was shown to stabilize the cream, whereas PE and sphingomyelin had no such effects. PC from soybean oil also was found to have emulsifying abilities. It was suggested that PC stabilized the reconstituted cream, regardless of its origin.     

ω-3 Fatty acids in smooth muscle cell phospholipids increase membrane cholesterol efflux

The aim of our work was to determine whether fatty acid modifications in smooth muscle cell phospholipids affect cholesterol efflux and desorption. [³H]Cholesterol was used to label cholesterol pools in the whole cell or selectively in the plasma membrane. Cells were incubated for 12 h in order to increase oleate, linoleate, arachidonate, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in phospholipids. Cholesterol efflux was monitored using native or tetranitromethane modified high-density lipoprotein₃ (HDL₃). When all cholesterol pools were labeled, the efflux from cells treated with different fatty acids were not different. Plasma membrane cholesterol efflux remained unchanged after oleate, linoleate or arachidonate treatments, but was markedly increased after EPA and DHA enrichment, both with native HDL₃ and with tetranitromethane-high-density lipoprotein. These results suggest that the positive effects of n−3 fatty acid consumption on the atherosclerotic process could be linked in part to an increase in plasma membrane cholesterol efflux from vascular smooth muscle cells.     

Fatty acid composition of milk phospholipids. III. Camel,ass, and pig milks

Phospholipids were isolated from camel, ass, and pig milks, and their fatty acid compositions were determined by gasliquid chromatography. The specific distributions of fatty acids in phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) were determined. The results are compared with previous results for bovine, sheep, Indian buffalo, and human milks. The milk phospholipids which were studied can be grouped, on the basis of their fatty acid compositions, into those from ruminant herbivores, nonruminant herbivores, and nonherbivores. The phospholipids of camel milk however have features typical of all groups as well as 15% plasmalogen in the PE fraction. For Parts I and II, see References 1 and 2.     

Fatty acid composition of milk phospholipids. II. Sheep,Indian buffalo and human milks

Phospholipids were isolated from sheep, Indian buffalo, and human milks, and their fatty acid compositions determined by gas chromatography. The specific distributions of fatty acids in phosphatidyl cholines (PC) and phosphatidyl ethanolamines (PE) were determined after phospholipase A hydrolysis. Fatty acid compositions and specific distributions were similar in sheep and buffalo milk phospholipids, and compared closely with those of bovine milk. Human milk phospholipids, particularly PE, contained much larger amounts of polyunsaturated acids, but negligible amounts of branchedchain acids. Palmitic and oleic acids were evenly distributed in human milk PC and PE, whereas they were preferentially located in the α′ position in PC and PE of ruminant milks. The results are discussed in the context of current theories of lipid biosynthesis. Part I of this series is “Fatty Acids of Bovine Milk Glycolipids and Phospholipids, and Their Specific Distribution in the Diacylglycerophospholipids,” W. R. Morrison, E. L. Jack and L. M. Smith. JAOCS,42, 1142–1147 (1965).     

Fatty acid distribution in lipids and32P incorporation into phospholipids during early amphibian development

Several aspects of lipid composition and³²P incorporation were studied during early embryogenesis of the toad,Bufo arenarum, Hensel. The surveyed stages ranged from unfertilized oocyte to neural tube formation. The fatty acid distribution in polar and neutral lipids, as well as in acetone eluate from Unisil columns was similar in unfertilized oocyte and late blastula stage. There was no significant effect of cell cleavage on the fatty acid composition of these lipid fractions. Neutral lipids represent ca. 67% of the total lipids. The main components of the phospholipids were phosphatides of choline and ethanolamine. The total lipid and phospholipid content does not change through the studied stage of neurula. However a large increment in the phospholipid's specific radioactivity occurs when³²P is injected along with the hormone to induce ovulation. It is suggested that this may reflect changes in turnover rates rather than net biosynthesis. Since a large amount of cell membranes is being formed during the early development and because the level of phospholipids remains constant, an explanation is offered regarding membranogenesis. Active phospholipid biosynthesis may take place during oogenesis. These lipids may be stored in the yolk platelet, and fertilization may regulate the functioning of a transport mechanism to corresponding membrane sites. The increased incorporation of³²P may reflect changes in the activity of new membranes.     

Composition and positional distribution of fatty acids in phospholipids isolated from pork muscle tissues

The composition and positional distribution of fatty acids in phospholipids isolated from four locations of a hog carcass is presented. Variations in fatty acid composition of phospholipids were found depending upon the location in the carcass. The total unsaturated fatty acid content averaged 34.3 mole % for lecithin, 52.5 mole % for phosphatidylethanolamine, 40.3 mole % for phosphatidylserine and 41.3 mole % in sphingomyelin. The cephalins had a much higher percentage of polyunsaturated fatty acids than lecithin. The chief saturated fatty acid in lecithin and sphingomyelin was palmitic and in cephalins it was stearic. A snake venom enzyme preparation(Crotalus adamanteus) hydrolyzed primarily unsaturated fatty acids in phosphoglycerides and the higher the percentage of unsaturation within the fatty acid the higher percentage of hydrolysis occurred. The unsaturated fatty acids were found chiefly at the theβ-position and the saturated fatty acids at thea-position in the phosphoglycerides. Michigan State Agricultural Experiment Station Publication No. 3389. Supported by the U.S. Public Health Service Research Grant No. GM 08801-03.