A method for the quantitative determination of neutral glycosphingolipids in urine sediment

A method is described for the isolation and quantitation of six neutral glycosyl ceramides from human urinary sediment. Total lipids were extracted from sediments of 24-hr urine collections, and the glycosyl ceramides were isolated by silicic acid column chromatography followed by thin-layer chromatography. Methanolysis of the individual glycosyl ceramides yielded methyl glycosides which were quantitated as the trimethylsilyl ethers by gas-liquid chromatography. By this technique, the submicromolar concentrations of six glycosyl ceramides in normal subjects and in individuals with Fabry's disease, an hereditary glycosphingolipid storage disease, were determined. Trihexosyl ceramide (galactosyl-galactosylglucosyl ceramide) and a digalactosyl ceramide accumulated in the urinary sediment of patients with Fabry's disease.     

Studies on the structure and I-blood-group activity of poly(glycosyl)ceramides.

Employing a modified technique of acetolysis, which allows almost a complete recovery of constituent sugars from poly(glycosyl)ceramides, the glycolipids were found to contain an excess of N-acetylglucosamine over galactose. On the basis of Smith degradation, methylation study, chromium trioxide degradation and the structures of oligosaccharides released from the glycolipids by partial acid hydrolysis, the presence of two types of sugar sequences has been established in poly(glycosyl)ceramides: a) Galbeta1 leads to 4GlcNAcbeta1 leads to 6Gal3 comes from R1 b) Galbeta1 leads to 4GlcNAcbeta1 leads to 4GlcNAc1 leads to R2. The repeating unit of poly(glycosyl)ceramides seems to be the GlcNAcbeta1 leads to 3Gal sequence. The specificity of one anti-I serum (Woj) is directed against the non-reducing ending of the first kind of chain. Three other anti-I sera reacted with inner portions of the oligosaccharide chains of the glycolipids.     

Composition and synthesis of glycolipids in megakaryocytes and platelets: differences in synthesis in megakaryocytes at different stages of maturation

The composition and synthesis of megakaryocyte and platelet glycolipids were compared since these lipids are thought to be important for biologic activities such as adhesion and maturation. Highly purified guinea pig megakaryocytes at different stages of maturation and platelets were studied. Glycolipids and gangliosides were extracted, separated by thin-layer chromatography, and the carbohydrate content was analyzed by gas-liquid chromatography (GLC). Synthesis of ceramides and glycolipids was determined by the incubation of megakaryocytes with [14C]acetate, [3H]palmitic acid, and [3H]galactose. A major neutral glycolipid present in guinea pig megakaryocytes and platelets was identified as asialoGM2 by selective enzymatic hydrolysis with beta-N-acetylhexosaminidase, alpha-galactosidase and endo-beta-galactosidase, and carbohydrate analysis by GLC. Trace amounts of asialoGM1 were detected immunologically. The cells also contained glucosyl ceramide and lactosyl ceramide. Several ganglosides were detected of which one was identified as GM1 by its reaction with the beta-subunit of cholera toxin and by the identification of an asialoGM1 core with anti-asialoGM1 antibody after desialylation. The synthesis of ceramides from palmitic acid and acetate was 5 and 10 times greater, respectively, in megakaryocytes than in platelets. Ceramide and glycolipid synthesis from palmitic acid occurred primarily in immature megakaryocytes while synthesis from acetate occurred primarily in more mature megakaryocytes. The glycosylation of ceramides from galactose was 42 times greater in megakaryocytes than in platelets. Thus, ceramides and glycolipids are primarily synthesized in megakaryocytes, but platelets retain the capacity to synthesize significant amounts of free ceramides. The glycosylation of free ceramides occurs almost exclusively in megakaryocytes and only in trace amounts in platelets. These data indicate that megakaryocytes determine the composition of glycolipids in platelets and that there is considerable compartmentalization of glycolipid synthesis and membrane assembly at various stages of megakaryocytes development.     

Separation and identification of ceramides derived from human plasma sphingomyelins

Sphingomyelins from human blood plasma have been converted into ceramides by enzymatic hydrolysis with phospholipase C. After acetylation the ceramides were fractionated by thin-layer chromatography on silica gel containing silver nitrate. Four main fractions obtained by this method were subsequently converted to di-O-trimethylsilyl ether derivatives and separated by gas-liquid chromatography on 1% OV-1. 2-11 components could be distinguished in each of the four fractions. The major fractions emerging from the gas chromatograph were analyzed by mass spectrometry and their main molecular species were identified. Two of the gas chromatographic fractions contained essentially pure molecular species, namely N-tetracosenoyl sphingosine and N-tetracosenoylsphinga-4, 14-dienine.     

Rapid transbilayer movement of ceramides in phospholipid vesicles and in human erythrocytes

The transbilayer diffusion of unlabeled ceramides with different acyl chains (C6-Cer, C10-Cer, and C16-Cer) was investigated in giant unilamellar vesicles (GUVs) and in human erythrocytes. Incorporation of a very small percentage of ceramides (approximately 0.1% of total lipids) to the external leaflet of egg phosphatidylcholine GUVs suffices to trigger a shape change from prolate to pear shape vesicle. By observing the reversibility of this shape change the transmembrane diffusion of lipids was inferred. We found a half-time for unlabeled ceramide flip-flop below 1 min at 37 degrees C. The rapid diffusion of ceramides in a phosphatidylcholine bilayer was confirmed by flip-flop experiments with a spin-labeled ceramide analogue incorporated into large unilamellar vesicles. Shape change experiments were also carried out with human erythrocytes to determine the trans-membrane diffusion of unlabeled ceramides into a biological membrane. Addition of exogenous ceramides to the external leaflet of human erythrocytes did not trigger echinocyte formation immediately as one would anticipate from an asymmetrical accumulation of new amphiphiles in the outer leaflet but only after approximately 15 min of incubation at 20 degrees C in the presence of an excess of ceramide. We interpret these data as being indicative of a rapid ceramide equilibration between both erythrocyte leaflets as indicated also by electron spin resonance spectroscopy with a spin-labeled ceramide. The late appearance of echinocytes could reveal a progressive trapping of a fraction of the ceramide molecules in the outer erythrocytes leaflet. Thus, we cannot exclude the trapping of ceramides into plasma membrane domains.     

Structural analysis of glycolipids from Borrelia burgdorferi

In this study the lipids of Borrelia burgdorferi, the causative agent of Lyme disease, were analyzed. Lipids comprise about 25-30% of the cell dry weight. The lipid fraction could be separated by HPTLC into 11 components. Staining of these components revealed two glycolipids and two phospholipids. The glycolipids represented about 50% of the total lipids and comprised only galactose as monosaccharide constituents. By means of mass spectrometric and gas chromatographic analysis both glycolipids could be identified as alpha-galactosyl-diacylglycerolipids with different fatty acid compositions. The phospholipids were identified as phosphatidylcholine and phosphatidylglycerol. Immunoassays with sera from patients with Lyme disease showed antibody reactivity only to the glycolipids, which was present in all stages of the disease. Other lipid components seemed to be non-immunogenic in Lyme disease. The glycolipids of B. burgdorferi may be, thus, considered promising candidates for diagnosis and possibly also for vaccination.     

Sphingolipid composition of human platelets

Total lipid extracts from washed trypsinized human platelets were fractionated into neutral lipids, glycosphingolipids, and phospholipids by silicic acid chromatography. The concentrations and chemical structures of the neutral and acidic glycosphingolipids were then studied in detail. On the basis of sugar molar ratios, studies of permethylation products, and the action of stereospecific glycosidases on the lipids, identifications were made of four neutral glycosphingolipids. Lactosylceramide was the most abundant type and accounted for 64% of the total neutral glycolipid mixture. The major fatty acids of the lactosylceramide were 20:0, 22:0, 24:0, and 24:1; the major long-chain base was 4-sphingenine. The platelets were surprisingly rich in a ceramide fraction, which represented 1.3% of the total platelet lipids. It had a different fatty acid composition than the neutral glycosphingolipid and ganglioside fractions. Hematoside was also isolated from the total lipid fraction of platelets; the neuraminic acid component was N-acetylneuraminic acid. Treatment of platelets with trypsin, chymotrypsin, or thrombin increased the yield of hematoside as compared with a control, while the level of ceramides was not changed. It was concluded that the platelets are similar to leukocytes, liver, and spleen in that lactosylceramide and hematoside are the principal neutral and acidic glycosphingolipids. The presence of a relatively high proportion of ceramide in platelets may be a unique characteristic of this cellular fraction of blood.     

Separation of neutral glycosphingolipids and sulfatides by thin-layer chromatography

Two one-dimensional systems for separation of glycolipids from total lipid extracts of tissues by thin-layer chromatography are described. System I used, as adsorbent, an alkaline mixture of silica gel without CaSO(4) binder (75%) and magnesium silicate (25%), and the lipids were "developed" with three successive solvent mixtures. The separated compounds (from the fastest to the slowest moving) were: ceramide, ceramide monohexosides, sulfatides, ceramide dihexosides, psychosine, ceramide trihexosides, and ceramide N-acetylhexosamine trihexosides. In system II a two-step development was used on an adsorbent consisting of silica gel without CaSO(4) binder (80%) and magnesium silicate (20%). The separated compounds were: ceramides, ceramide monohexosides, and ceramide dihexosides. Psychosine and sulfatides as well as ceramide trihexosides and ceramide N-acetylhexosamine trihexosides were not separated. In both systems all neutral lipids moved to the very top of the chromatogram and phospholipids stayed at the origin. Application of systems I and II for separation of glycolipids was demonstrated on total lipid extracts from animal tissues.     

High performance thin-layer chromatography and densitometry of synaptic plasma membrane lipids

Previously, it has been shown that phospholipids, cholesterol, and glycolipids could be quantitated using the same high performance thin-layer chromatography (HPTLC) method. Here we examined that method in terms of linearity of standards in the nanogram range, recovery of nonacidic and acidic lipids after Sephadex column chromatography, and quantitation of lipids in mouse synaptic plasma membranes (SPM) where lipid content is low. Nonacidic and acidic fractions were separated by Sephadex column chromatography, applied to plates using contact spotting, chromatographed, visualized with cupric acetate, and quantitated using in situ densitometry. Recovery of nonacidic and acidic fractions off the columns was determined with radiolabeled phospholipids. Standards for each lipid class were linear in the nanogram range. Quantitation of SPM lipid classes could be made with as little as 1.5 micrograms of total lipid. Recovery of the nonacidic fraction after Sephadex column chromatography was approximately 100% whereas the acidic fraction was approximately 91%. Phospholipids, cholesterol, and glycolipids could be determined in nanogram amounts using the same method. This method is an efficient method for examining different lipid classes and in samples where lipid content is low.     

Polar lipids in cosmetics: recent trends in extraction,separation, analysis and main applications

Demand for active, natural, safe and biomimetic (similar to human molecules) plantderived cosmetic ingredients is always greater because consumers are increasingly suspicious of the potential toxicity of current ingredients. In this context, interest has increased for polar lipids like ceramides, sphingolipids or glycolipids that share structural properties with the skin lipids. In the same manner, processes to obtain such lipids should be driven by the principles of green chemistry and sustainable development. The identified needs are biodegradability, biocompatibility, efficiency, quality and profitability. In this research for new and novel natural or ‘green’ compounds, the development of bioactive lipids thanks to ecofriendly processes has obviously intensified, especially for cosmetic and agro-food industries. This paper reviews extraction methods for polar lipids (glycolipids and phospholipids), especially ecoprocesses (supercritical fluid extraction, microwaves, sonication, enzyme extraction…), and promising chromatographic methods like countercurrent chromatography, supercritical fluid chromatography or high performance chromatography coupled to mass spectrometry Interests of polar lipids for cosmetic industries are exemplified to show their broad applications mostly relying on their amphiphilic properties allowing them to play functional roles (liposome or micelle structures for example) or physiological roles (skin barrier function or anti-ageing effect).     

Glycolipid antigens with blood group I and i specificities from human adult and umbilical cord erythrocytes

Neutral glycolipids and gangliosides of umbilical cord and adult human erythrocytes were separated by high performance liquid chromatography, and each fraction was analyzed by direct binding of anti-I (Ma) and anti-i (Den) on solid phase glycolipid-lecithin-cholesterol. The I- and i-active glycolipids were isolated and their structures were determined by methylation analysis and direct probe mass spectrometry. The major I antigen in adult erythrocytes, showing a remarkable binding activity with anti-I(Ma), was found in one neutral glycolipid fraction, designated fraction y4, which was identified as a mixture of two glycolipids of a new type, lactoisooctaosylceramide and monofucosyllactoisooctaosylceramide (for structures, see Table I). In addition, two gangliosides displaying direct binding activity with anti-I(Ma) were identified as monosialoganglioside G8, as previously described and disialosyllactoisooctaosylceramide, which showed the same level of I activity as the y4 glycolipid. The same ganglioside was recently isolated and characterized by Kundu and co-workers. The major i-active glycolipid antigen in umbilical cord erythrocytes, showing a strong binding activity with anti-i(Den), was a neutral glycolipid, x4a, which was identified as lactonorhexaosylceramide. This glycolipid without fucosyl or sialosyl substitution has not been isolated previously and was present as an obvious normal component of umbilical cord erythrocytes, but an extremely minor component of adult erythrocytes. Sialosyllactonorhexaosylceramide (G6) was isolated and characterized as a second i antigen of umbilical cord erythrocytes, but showed a very weak binding activity with the anti-i antibody. Although these sialosyl derivatives displayed only weak activity, the chemical quantity of the sialosyl derivatives is significantly large in fetal erythrocytes; therefore, Ii activity of human erythrocytes, in general, must be significantly dependent on sialosyl derivatives in addition to unsubstituted structures.     

Lipid composition of lysosomal multilamellar bodies of male mouse urine

Previous studies from our laboratory have shown that male C57BL/6J mice excrete into the urine multilamellar lysosomal bodies that contain specific neutral glycosphingolipids. These mice excrete approximately 20-30% of their kidney glycolipids each day. The significance and function of this secretion of multilamellar lysosomal organelles is unknown. To characterize these excreted bodies further, we report here their neutral lipid and phospholipid composition. The bodies were collected by differential centrifugation, extracted with chloroform-methanol, and lipids were fractionated into neutral lipids, glycolipids, and phospholipids. The neutral lipids consisted primarily of cholesterol, dolichol, and ubiquinone. The phospholipid fraction consisted primarily of a single molecular species of phosphatidylcholine. This lipid which comprises more than 90% of the total phospholipids was found to contain 16:0 ether and C22:6 n-3 fatty acid as determined by gas-liquid chromatography-mass spectrometry. The glycosphingolipids as reported previously consisted primarily of galabiosylceramides and globotriaosylceramides. This membrane lipid composition is different from any previously reported cellular organelle.     

Complete Polar Lipid Composition of Thermoplasma acidophilum HO-62 Determined by High-Performance Liquid Chromatography with Evaporative Light-Scattering Detection

Polar ether lipids of Thermoplasma acidophilum HO-62 were purified by high-performance liquid chromatography with an evaporative light-scattering detector. Structures of purified lipids were investigated by capillary gas chromatography, mass spectrometry, and nuclear magnetic resonance. Three types of ether lipids were found: phospholipids, glycolipids, and phosphoglycolipids. The two phospholipids had glycerophosphate as the phosphoester moiety. The seven glycolipids had different combinations of gulose, mannose, and glucose, which formed mono- or oligosaccharides. The eight phosphoglycolipids with two polar head groups contained glycerophosphate as the phosphoester moiety and gulose alone or gulose and mannose, which formed mono- or oligosaccharides, as the sugar moiety. Although gulose is an unusual sugar in nature, several glyco- and phosphoglycolipids contained gulose as one of the sugar moieties in Thermoplasma acidophilum. All the ether lipids had isopranoid chains of C(40) or C(20) with zero to three cyclopentane rings. The structures of these lipids including four new glycolipids and three new phosphoglycolipids were determined, and a glycosylation process for biosynthesis of these glycolipids was suggested.     

Hydrazinolysis of glycosphingolipids. A new method for preparation of N-deacylated (lyso) glycosphingolipids

A useful method for N-deacylation of the ceramide moiety of glycosphingolipids has been developed. Galactosylceramide, glucosylceramide, lactosylceramide, and galactosyllactosylceramide were effectively deacylated by heating with anhydrous hydrazine at 150 degrees C for 15-25 h. The lyso-derivative as the deacylated product of the ceramide moiety of each glycosphingolipid was isolated by preparative silica gel thin layer chromatography with a 70-85% yield from the starting glycolipids. Hydrazine sulfate was an effective catalyst for the deacylation of the ceramide moiety. No dissociation of oligosaccharide moieties of the glycolipids on hydrazinolysis was confirmed by gas chromatographic analysis and N-acylation of these lysoderivatives. The free amino groups of the lysoglycosphingolipids can be combined with various kinds of probes giving useful derivatives for biochemical and immunological studies on glycosphingolipids.     

Structures of polar lipids from the thermophilic, deep-sea archaeobacterium Methanococcus jannaschii

Cells of Methanococcus jannaschii, grown at 65 degrees C in a defined medium, contained 7% of lipid composed of 87% polar and 13% neutral components. Within the polar fraction 16 lipids were resolved by thin-layer chromatography, 4 of which were present in trace amounts. Staining reactions demonstrated that the more abundant lipids were glycolipids, aminophospholipids, and an aminophosphoglycolipid. Most of the polar fraction (82%) consisted of five diether lipids, which were purified and their structures were resolved largely through nuclear magnetic resonance, mass spectrometry, and optical rotation methods. Macrocyclic diethers had the head groups phosphoethanolamine-(1----6)-beta-D-glucopyranose, beta-D-glucopyranose, and beta-D-glucopyranosyl-(1----6)-beta-D-glucopyranose. Phosphoethanolamine was identified as a head group for both the noncyclized and macrocylic diether core lipids. The neutral lipids were mainly acyclic C30 isoprenoids, predominantly dihydro-, hexahydro, and octahydro-squalenes.     

The fatty acid and monosaccharide compositions of three neutral and three phosphorylated glycolipids isolated from Leishmania donovani promastigotes grown in a chemically defined medium

Several lipids and macromolecular lipoconjugates of Leishmania spp. have now been well characterized; however, the glycolipids of L. donovani have not been thoroughly examined. In the present study, 3 neutral and 3 phosphorylated glycolipids were detected in promastigote forms of the organism grown in a chemically defined medium. The fatty acid and sugar compositions of these glycolipids, isolated and purified by adsorption column chromatography and thin-layer chromatographic procedures, were identified and quantified by gas-liquid chromatography and mass spectrometry. Myristate (14:0), palmitate (16:0), palmitoleate (16:1), stearate (18:0), oleate (18:1), and linoleate (18:2) were the major fatty acids in all 6 glycolipids. Arabinose, mannose, glucose, and galactose were detected in the glycolipids. The biochemical nature of these lipids suggested that the major components in the isolated preparations of the 6 glycolipids are diacylglycerophospholipids, distinct from the major precursors of macromolecular lipoconjugates such as the lipid anchors of cell surface antigens that have been reported. These appear to be terminal products of lipid biosynthesis in this parasite.     

Lipid composition and thermotropic phase behavior of boar, bull, stallion, and rooster sperm membranes.

Composition and thermotropic phase behavior of sperm membrane lipids from species ranging in sensitivity to cold shock were determined. Lipids from whole sperm and sperm plasma membrane were fractionated into neutral lipid, glycolipid, and phospholipid fractions. Compositional analyses were completed for free sterols, phospholipids and phospholipid-bound fatty acids. Phase transition temperatures were determined for phospholipid and glycolipid fractions using differential scanning calorimetry. Cholesterol was the major sterol in sperm lipids of all species. Cholesterol to phospholipid molar ratios were 0.26, 0.30, 0.36, and 0.45 for sperm plasma membrane of the boar, rooster, stallion, and bull, respectively. Choline and ethanolamine phosphoglycerides and sphingomyelin were the major phospholipid classes in sperm and their proportions differed across species. Phospholipid-bound fatty acyl compositions of choline and ethanolamine phosphoglycerides were characterized by a high proportion of docosapentanoyl and docosahexanoyl groups in mammalian sperm and shorter, more saturated groups in rooster sperm. Glycolipids represented less than 10% of total polar lipids for all species. Thin-layer chromatographic analysis indicated that the major glycolipid component of rooster sperm was different from that of mammalian sperm. Peak phase transition temperatures (Tm) for sperm membrane phospholipids were 24.0, 25.4, 20.7 and 24.5, for the boar, stallion, and rooster, respectively. Corresponding Tm's for glycolipids were 36.2, 42.8, and 33.4 with no exotherm for rooster sperm glycolipids. These results demonstrate a difference in both composition and thermotropic phase behavior of glycolipids between rooster and mammalian sperm which may be related to the greater tolerance of rooster sperm to rapid cooling.     

Glycosphingolipid composition of human semen

Glycosphingolipids were extracted from human semen and purified. Based on the fluorometric assay of sphingosine, in spermatozoa a content of 4.4 +/- 0.9 nmol/10(8) cells of gangliosides and 22.1 +/- 1.7 nmol/10(8) cells of neutral glycosphingolipids was determined. Seminal plasma contained 4.1 +/- 0.6 nmol gangliosides and 29.3 +/- 1.5 nmol neutral glycosphingolipids per milliliter. The glycosphingolipid component patterns of human spermatozoa and seminal plasma were determined by thin-layer chromatography. Four neutral glycolipids were isolated and their carbohydrate moieties were characterized. All of these glycolipid components belonged to the globo-series. Gas chromatography, combined gas chromatography/mass fragmentography, and exoglycosidase treatments revealed the following structures for the glycosphingolipids of human semen: Glc1-Cer, Gal beta 1-4Glc1-Cer, Gal alpha 1-4Gal beta 1-4Glc1-Cer, and Gal-NAc beta 1-3Gal alpha 1-4Gal beta 1-4Glc1-Cer. In addition, the occurrence of trace amounts of lactoneotetraosyl- and lactoneohexaosylceramide was detected by immunostaining after thin-layer chromatographic separation. Human spermatozoa, as well as seminal plasma, contained the gangliosides Glac1,Glac2, a sialolactoneotetraosylceramide, and a sialolactoneohexaosylceramide. The gangliosides were identified on the basis of their running characteristics by high-performance thin-layer chromatography, exoglycosidase treatment, and immunostaining after thin-layer chromatography. The ceramide composition of the glycolipids in human spermatozoa, as well as in seminal plasma, was dominated by C22:0-behenic acid and the saturated sphingoid d18:0, sphinganine.     

Lipid-mediated glycosylation of endogenous proteins in isolated plasma membrane of Saccharomyces cerevisiae.

A highly purified plasma membrane fraction from Saccharomyces cerevisiae was obtained by centrifugation on discontinuous sucrose and Urografin gradients. This plasma membrane fraction was capable of glycosylating endogenous proteins. It is shown that glycolipids play an intermediate role in these glycosylation reactions; with uridine 5'-diphosphate-N-acetylglucosamine as sugar donor the intermediate lipids possessed stability towards alkali and chromatographic mobilities similar to polyprenyl diphosphate N-acetylglucosamine and polyprenyl diphosphate di-N-acetylchitobiose.     

Immunochemistry of Ii-active glycosphingolipids of erythrocytes.

Fractions of complex glycosphingolipids were prepared from adult, cord, and i phenotype erythrocytes by the method elaborated for the isolation of poly(glycosyl)ceramides. In contrast to poly(glycosyl)ceramides which comprise on the average 30 glycosyl units and about 5 branching points, i.e. 3,6-di-O-substituted galactopyranosyl residues, per mole of glucose, complex glycosphingolipids from cord and i erythrocytes comprise 6 and 15 glycosyl units respectively and only 0.7 branching points. The latter substances exhibited also a high i activity which was not detected in poly(glycosyl)ceramides. Erythrocyte membranes were labeled with radioactive N-acetylgalactosamine (GalNAc) from UDP-GalNAc using a purified A-blood-group gene-specified transfered of GalNAc. It was found that electrophoretic mobilities in dodecylsulfate-gel electrophoresis of all glycoconjugates which accepted GalNAc were increased in i as compared to I membranes. We conclude that the absence of highly branched glycosphingolipids in cord and i erythrocytes as well as the reduction of apparent molecular weights of the glycoconjugates, which are substrates for A-gene-specified transferase of GalNAc, result from a single cause, that is an inadequacy of the biosynthetic process which is responsible for the formation of GlcNAc1 leads to 6Gal structures.