Showing papers in "Lipids in 1981"
TL;DR: In this article, pure hydroperoxides from autoxidized and photosensitized oxidized fatty esters were thermally decomposed in the injector port of a gas chromatograph-mass spectrometer system.
Abstract: To clarify the sources of undesirable flavors, pure hydroperoxides from autoxidized and photosensitized oxidized fatty esters were thermally decomposed in the injector port of a gas chromatograph-mass spectrometer system. Major volatile products were identified from the hydroperoxides of methyl oleate, linoleate and linolenate. Although the hydroperoxides from autoxidized esters are isomerically different in position and concentration than those from photosensitized oxidized esters, the same major volatile products were formed but in different relative amounts. Distinguishing volatiles were, however, produced from each type of hydroperoxide. The 9- and 10-hydroperoxides of photosensitized oxidized methyl oleate were thermally isomerized in the injector port into a mixture of 8-, 9-, 10- and 11-hydroperoxides similar to that of autoxidized methyl oleate. Under the same conditions, the hydroperoxides from autoxidized linoleate and linolenate did not undergo significant interconversion with those from the corresponding photosensitized oxidized esters. The compositions of the major volatile decomposition products are explained by the classical scheme involving carboncarbon scission on either side of alkoxy radical intermediates. Secondary reactions of hydroperoxides are also postulated, and the hydroperoxy cyclic peroxides from methyl linoleate (photosensitized oxidized) and methyl linolenate (both autoxidized and photosensitized oxidized) are suggested as important precursors of volatiles.
269 citations
TL;DR: The two dry column methods-isocratic or sequential elution-were compared with the traditional chloroform/methanol methods by gravimetric, thin layer chromatographic and phosphorus analyses.
Abstract: A method for lipid isolation is presented that is alternative to the traditional chloroform/methanol extraction methods. This new method allows lipid isolation by solvent elution of a dry column composed of a tissue sample, anhydrous sodium sulfate, and Celite 545 diatomaceous earth groud together. To isolate total lipids, the dry column is eluted with a mixture of dichloromethane/methanol (90∶10, v/v). Alternatively, the lipids may be isolated and simultaneously separated into neutral and polar fractions by a sequential elution procedure; neutral lipids free of polar lipids are eluted first with dichloromethane, followed by elution of polar lipids with the dichloromethane/methanol (90∶10) mixture. The two dry column methods-isocratic or sequential elution-were compared with the traditional chloroform/methanol methods by gravimetric, thin layer chromatographic and phosphorus analyses.
188 citations
TL;DR: The phase behavior of monoglyceride/water systems, with oleic and linoleic acid as the dominating fatty acid residues, was investigated and the cubic phase is found to be easily dispersed.
Abstract: The phase behavior of monoglyceride/water systems, with oleic and linoleic acid as the dominating fatty acid residues, was investigated. Increased solubilization of triglycerides (oil) or oleic acid in the cubic liquid-crystalline phase formed by monoglyceride and water resulted in the formation of a reversed hexagonal liquid-crystalline phase followed by an L2-phase. The liquid-crystalline phases have different dispersion properties compared to each other in dilute micellar bile salt solutions. The cubic phase is found to be easily dispersed. The relevance of aqueous lipid phases other thah micellar is discussed in relation to intestinal lipid digestion and absorption.
132 citations
TL;DR: In this paper, an analytical method to obtain detailed compositions of the fatty acids in oils containing more than one conjugated octadecatrienoic acid by open-tubular gas liquid chromatography (GLC) and by reversed-phase HPLC were established.
Abstract: Analytical methods to obtain the detailed compositions of the fatty acids in oils containing more than one conjugated octadecatrienoic acid by open-tubular gas liquid chromatography (GLC) and by reversed-phase high performance liquid chromatography (HPLC) were established. Effective GLC separations ofcis,trans,trans-9,11,13-octadecatrienoic acid (ctt-9,11,13–18∶3),ctc-9,11,13–18∶3,ttc-9,11,13–18∶3,ttt-9,11,13–18∶3,ttc-8,10,12–18∶3, andttt-8,10,12–18∶3 were obtained with an opentubular column coated with the nonpolar liquid phase OV-1 using an instrument having all-glass carrier gas pathways. The HPLC method also gave satisfactory separations for the isomeric conjugated octadecatrienoates on the basis of number of thecis andtrans double bonds. Two or three minor conjugated trienoic acids were found along with the principal conjugated trienoic acid in tung oil, and seed oils of cherry,Prunus sp., Momordica charantia, Trichosanthes anguina, Punica granatum, Catalpa ovata, andCalendula officinalis. The mechanism for the formation of the conjugated trienoic acid mixtures in the seed oils is discussed. TheC. ovata seed oil also containedct andtt-9,12-octadecadienoic acids. Thett isomer is presumed to be a precursor ofttc-9,11,13–18∶3, the main conjugated trienoic acid in this oil.
109 citations
TL;DR: A model for the metabolism of oxidized membrane phospholipids is proposed and it is proposed that fatty acid epoxide,cis-9,10-epoxystearic acid, was rapidly hydrated by microsomal and cytosolic epoxide hydrolase.
Abstract: The isolation and measurement of phospholipid epoxides as major peroxidation products in biomembrane preparations prompted an investigation of enzymatic mechanisms which may be responsible for their elimination. Analysis of microsomal epoxide hydrolase and phospholipase A2 activity against a phospholipid epoxide commonly encountered in tissues indicated it to be a poor substrate for epoxide hydrolase, but rapidly hydrolyzed by phospholipase A2. Microsomal and purified phospholipase A2 preparations hydrolyzed the phospholipid epoxide at rates 2-fold greater than were observed with a monoenoic phospholipid from which the epoxide would be derived. The product fatty acid epoxide,cis-9,10-epoxystearic acid, was rapidly hydrated by microsomal and cytosolic epoxide hydrolase. On the basis of earlier reports demonstrating increased phospholipase activity against oxidized phospholipids, and on the results of the present study, a model for the metabolism of oxidized membrane phospholipids is proposed.
108 citations
TL;DR: Analysis of the phospholipid-bound fatty acids in a sponge cell-enriched fraction indicated that the demospongic acids, including the 2 branched structures, were the major acids of the sponge cells.
Abstract: The free sterols and phospholipids of the demospongeAplysina fistularis were isolated and analyzed. The free sterols consisted mainly of the unusual 26-methylated sterols aplysterol (53%) and 24(28)-dehydroaplysterol (7%) together with 7 commonly occurring sterods. The major phospholipids were phosphatidylcholine, phosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, phosphatidylserine and diphosphatidylglycerol. The major fatty acyl components of the phospholipids consisted of 85% C14−C20 acids, including the unprecedented 2,6,10-trimethyl-5-tetradecenoic acid and 11-methyloctadecanoic acid. The remaining 15% were C27−C30 demospongic acids, including 2 novel acids tentatively assigned the structures 5,9,23-octacosatrienoic acid and 5,9,23-nonacosatrienoic acid, and 3 novel acids proven to be 5,9,21-octacosatrienoic acid, Z,Z-20-methyl-5,9-hexacosadienoic acid and Z,Z-22-methyl-5,9-octacosadienoic acid. The biosyntheses of the novel demospongic acids are proposed to occur by chain elongation of monoenoic or branched precursors followed by desaturation. The large quantities of typically bacterial phospholipids and fatty acids found implied the presence of bacteria in the sponge, in agreement with microscopic studies. Analysis of the phospholipid-bound fatty acids in a sponge cell-enriched fraction indicated that the demospongic acids, including the 2 branched structures, were the major acids of the sponge cells. The presence inA. fistularis of demospongic acids containing membrane disordering groups—methyl branches or double bonds—on the ω7 carbon is proposed to be due to the need by the sponge for membranes possessing fluidity near the middle of the phospholipid bilayer. It is also proposed that the C26 methyl group of aplysterol causes disordering of the phospholipid bilayer in the same region, and thus also evolved in response to this need.
107 citations
TL;DR: It is found that the problem is caused by washing the initially produced ghost material with the same buffer solut ion used in the initial preparation, and a high yield o f white ghosts is obtained after only 2 washes.
Abstract: In fol lowing the published procedures for the preparat ion o f ghosts f rom human erythrocytes (1,2), we have consis tent ly been t roubled by the persistence through successive washes, of a small vo lume of somewhat more dense, redcolored material. Prolonged standing of the ghost membranes in cold, hypo ton ic buffer (1-12 hr), or the addi t ion of EDTA, or change in the pH of the buffer did not improve the si tuation. Unfor tuna te ly , we could no t simply discard this red material because we ul t imate ly wished to per form a quant i ta t ive ex t rac t ion o f the lipids f rom the ghost membranes . We have found that the problem is caused by washing the initially produced ghost material with the same buffer solut ion used in the initial preparation. By a simple modif ica t ion of the published procedure so that washing is performed with buffers of successively weaker concent ra t ion , a high yield o f white ghosts is obtained after only 2 washes. Our procedure fol lows the me thod of Steck and Kant up to the initial preparat ion o f the ghosts (2). Thus, red b lood cells freshly donated or obta ined f rom the Red Cross Blood Bank are washed 3 t imes in phosphate-buffered saline and a sample of the washed, packed, red b lood cells is hemolyzed by rapid and thorough mixhag with chilled 5 mM phosphate buffer , pH 8.0. The ghost pellet obta ined after centrifugation and aspiration of the supernatant is washed by resuspending it in 2.5 mM phosphate buffer ,
105 citations
TL;DR: Diet-induced fatty acid changes in platelet and aortic lipids, platelet aggregation and thromboxane and prostacyclin formation are discussed and platelet cyclooxygenase appeared to be selectively depressed.
Abstract: Semisynthetic diets containing either corn oil (CO) or butter (B) (11 and 2.2 en % as linoleic acid, respectively) were fed to male rabbits for periods of 3 weeks and 3 months. The CO diet, in respect to the B diet, induced higher levels of linoleic acid (LA) and lower levels of arachidonic acid (AA) in platelet phospholipids, lower levels of AA in aortic phosphatidylinositol (PI) and accumulation of both LA and AA in liver lipids. The thresholds for aggregation with AA, but not with collagen, were higher in the CO group and the formation of thromboxane B2 (TXB2) from [14C] AA, but not from endogenous substrate after collagen stimulation, was lower in the same group. Formation of PGE2-like material by incubated aortas was higher in the B group. In the CO group, platelet cyclooxygenase appeared to be selectively depressed. The correlations among diet-induced fatty acid changes in platelet and aortic lipids, platelet aggregation and thromboxane and prostacyclin formation are discussed.
102 citations
TL;DR: In this article, the fatty acid constituents of the lipid fraction of royal jelly were characterized by thin layer chromatography of corresponding methyl esters, and the most common characteristic of the organic acids was that most contained 8 or 10 carbon atoms, whether saturated or unsaturated, linear or branched.
Abstract: This present work characterizes the fatty acid constituents of the lipid fraction of royal jelly. Among the organic acids found after fractionation by thin layer chromatography of the corresponding methyl esters, the following compounds were identified by combined GC-MS: saturated and unsaturated linear fatty acids, saturated and unsaturated linear and branched dicarboxylic acids, mono-and dihydroxy acids. The most common characteristic of the organic acids was that most contained 8 or 10 carbon atoms, whether saturated or unsaturated, linear or branched.
102 citations
TL;DR: A previous study of autoxidation products by high pressure liquid chromatography (HPLC) of methyl oleate and linoleate was extended to methyl linolenate.
Abstract: A previous study of autoxidation products by high pressure liquid chromatography (HPLC) of methyl oleate and linoleate was extended to methyl linolenate. Autoxidized methyl linolenate was fractionated by HPLC either after reduction to allylic alcohols on a reverse phase system, or directly on a micro silica column. Isolated oxidation products were characterized by thin layer and gas liquid chromatography and by ultraviolet, infrared, nuclear magnetic resonance and mass spectrometry. Secondary products from the autoxidation mixtures (containing 3.5–8.5% monohydroperoxides) included epoxy unsaturated compounds (0.2–0.3%), hydroxy or hydroperoxy-cyclic peroxides (3.8–7.7%), epoxy-hydroxy dienes (<0.1%), dihydroxy or dihydroperoxides with conjugated diene-triene and conjugated triene systems (0.9–2.9%). Cyclization of the 12- and 13-hydroperoxides of linolenate would account for their lower relative concentration than the 9- and 16-hydroperoxides. Dihydroperoxides may be derived from the 9- and 16-linolenate hydroperoxides. Cyclic peroxides and dihydroperoxides are suggested as important flavor precursors in oxidized fats.
101 citations
TL;DR: Upon incubation of microsomes with high concentrations of [14C] oleoyl-CoA, bovine serum albumin and NADH, it could be conclusively demonstrated that most oleic acid is desaturated while part of the PC molecule.
Abstract: Microsomes of developing soya bean cotyledons transfer oleate from oleoyl-CoA to phosphatidylcholine (PC) by two different mechanisms: one in which oleate transfer is accompanied by the release of free CoA and another which results in the exchange of oleate from oleoyl-CoA for unsaturated 18-carbon fatty acids of PC. The acyl exchange can be demonstrated only when bovine serum albumin is present in the incubation medium. ATP-dependent acyl-CoA synthetase is not involved in the exchange process, which apparently does not require any cofactors. In light of this exchange process, the oleate desaturase system was reinvestigated in order to determine what the actual substrate for this system is. Upon incubation of microsomes with high concentrations of [14C] oleoyl-CoA, bovine serum albumin and NADH, it could be conclusively demonstrated that most oleic acid is desaturated while part of the PC molecule. The amounts of [14C] linoleoyl-CoA formed could be explained entirely by the acyl exchange. The physiological significance of the acyl exchange system is discussed. A new method for separation of acyl-CoA from other lipids and free CoA using reversed phase column chromatography also is described.
TL;DR: The content of 4-demethyl-, 4-monomethyl- and 4,4-dimethylsterols in 13 vegetable oils was found to vary between 0.10-1.4%, 0.01-0.08% and 0.02- 0.29%, respectively as discussed by the authors.
Abstract: The content of 4-demethyl-, 4-monomethyl- and 4,4-dimethylsterols in 13 vegetable oils was found to vary between 0.10–1.4%, 0.01–0.08% and 0.02–0.29%, respectively. The largest amount of demethylsterols was found in maize and wheat germ oils, whereas the largest amounts of the dimethylsterols were found in olive and linseed oils. The predominating demethylsterols were sitosterol, campesterol, stigmasterol and Δ5-avenasterol. Among the 4-monomethylsterols, obtusifoliol, gramisterol, cycloeucalenol and citrostadienol predominated, but usually more than 10 components were found in this fraction. The composition of the 4,4-dimethylsterol fraction was also rather complex, with the 9,19-cyclopropanesterols together with α- and β-amyrin predominating. In most of the oils, characteristically high or low percentages of some sterols were found, and a few specific sterols were also noted. A scheme useful for characterization is presented.
TL;DR: Results show that peritoneal macrophages constitute one of the best systems to study in evaluating the metabolism of oxygenated products of arachidonic acid.
Abstract: Mouse peritoneal macrophages synthesize 6 monohydroxylated eicosatetraenoic acids when incubated with exogenous arachidonic acid. These compounds were identified by chromatographic techniques (high pressure liquid chromatography and high efficiency glass capillary column gas chromatography and mass spectrometry. The chromatographic and spectrometric data are presented. These results show that peritoneal macrophages constitute one of the best systems to study in evaluating the metabolism of oxygenated products of arachidonic acid.
TL;DR: Elevation in lipoprotein cholesterol was associated in all groups with an increased ratio of cholesterol to protein, suggesting the formation of particles relatively rich in cholesterol.
Abstract: The effect of different proportions of casein in semipurified diets on the concentation of serum cholesterol and the lipoprotein composition was studied in rabbits. Low-casein diets (10% w/w) resulted in serum cholesterol levels and growth rates that were lower than high-casein diets (40%). An intermediate proportion of casein (20%) produced intermediate concentrations ofserum cholesterol, but only minor differences in food intake and weight gain, compared with the high-casein group. In the animals with the highest values of total serum cholesterol (the 40% casein group), most of the serum cholesterol was transported in the very low density lipoproteins, whereas with moderate hypercholesterolemia (the 20% casein group), the low density lipoproteins were the main carriers of cholesterol. Elevation in lipoprotein cholesterol was associated in all groups with an increased ratio of cholesterol to protein, suggesting the formation of particles relatively rich in cholesterol. When the rabbits on the diet containing 10% casein were subsequently transferred to the 40% casein diet, a steep increase in the level of serum cholesterol occurred. Conversely, switching the rabbits on the 40% casein diet to the 10% casein diet resulted in a decrease in the level of serum cholesterol.
TL;DR: The liver mitochondria of normal rats and from rats made hypothyroid by thyroidectomy and injection with131INa contained similar amounts, per mg protein, of total lipids, phospholipids, neutral lipids and lipid phosphorus as mentioned in this paper.
Abstract: The lipids of liver mitochondria prepared from normal rats and from rats made hypothyroid by thyroidectomy and injection with131INa contained similar amounts, per mg protein, of total lipids, phospholipids, neutral lipids and lipid phosphorus. Hypothyroidism caused a doubling of the relative amounts of mitochondrial cardiolipins (CL; to 20.5% of the phospholipid P) and an accompanying trend (although statistically not significant) toward decreased amounts of both phosphatidylcholines (PC) and phosphatidylserines (PS), with phosphatidylethanolamines (PE) remaining unchanged. The pattern of elevated 18∶2 fatty acyl content and depleted 20∶4 acyl groups of the mitochondrial phospholipids of hypothyroid preparations was reflected to varying degrees in the resolved phospholipids, with PC showing greater degrees of abnormality than PE, and CL showing none. Hypothyroidism produced the same abnormal pattern of fatty acyl distributions in liver microsomal total lipids as was found in the mitochondria. Hypothyroid rats, when killed 6 hr after injection of [1-14C] labeled linoleate, showed the following abnormalities: the liver incorporated less label into lipids, and converted 18∶2 not exclusively to 20∶4 (as normals do) but instead incorporated the label mainly into saturated fatty acids. These data, together with the known decrease in β-oxidation, suggest that hypothyroidism involves possible defective step(s) in the conversion of 18∶2 to 20∶4.
TL;DR: The altered morphology and composition of fetal LDL, together with the lack of VLDL, suggest that the LDL particles may be synthesized de novo.
Abstract: Serum lipoproteins in fetal and newborn calves were characterized and compared with those of adult animals. Fetal calf serum contains only low density (LDL) and high density (HDL) lipoproteins; the LDL is the major lipoprotein class. Fetal LDL are ca. 26.0 nm diameter and are morphologically unusual in that particles form linear aggregates or “chains” in which LDL have flattened, parallel sides. These particles contain only apolipoprotein B and are high in polar lipids. Fetal HDL consist of 8.2-nm, round particles which contain large amounts of chlesteryl ester thus suggesting an active lecithin: cholesterol acyltransferase system in the fetal state. The major protein in fetal HDL is apolipoprotein A−I (80%); however, another component with a molecular weight (MW) of ca. 9,000 is also present. Newborn calves show a 5-fold increase in HDL concentration. These particles are 9.0 nm spherical particles and they contain mainly apolipoprotein A−I although C-apolipoproteins are also present; the lipid and apolipoprotein composition of newborn HDL is similar to that of adults. Newborn calves possess very low density (VLDL) lipoproteins which have a mean diameter of 61 nm and are similar in size and composition to those of adult animals; their apolipoprotein composition is principally apolipoprotein B, although C-apolipoproteins and apolipoprotein A−I are also present. The LDL of neonatal and adult animals are similar in morphology, chemical composition and apolipoprotein content. In both instances, LDL are round particles ca. 19.0 nm diameter which contain less polar lipids than the fetal animal. Apolipoprotein B is the major protein in newborn LDL, but adult LDL additionally contains a protein of 27,000 MW which probably represents apolipoprotein A−I from overlapping α-migrating particles in this region. The altered morphology and composition of fetal LDL, together with the lack of VLDL, suggest that the LDL particles may be synthesized de novo.
TL;DR: The difference between goats and cows in the effectiveness with which these animals metabolize propionyl- CoA and methylmalonyl-CoA is discussed.
Abstract: Branched-chain fatty acids of the milk fat of goats were analyzed by high resolution gas chromatography-mass spectrometry. Iso- and anteiso-acids predominated, but a range of other monomethyl-branched components, mostly with methyl-substitution on carbons 4 and 6, was present. Analysis of the milk fat of cows revealed the presence of iso- and anteiso-fatty acid; other mono-methyl-substituted fatty acids, as found in the milk fat of the goat, were virtually absent. Only a trace amount of 6-methylhexadecanoate was detected. The difference between goats and cows in the effectiveness with which these animals metabolize propionyl-CoA and methylmalonyl-CoA is discussed.
TL;DR: The lymphatic absorption of nonvolatile oxidation products (NVOP) formed during heating of fats was studied and indicated that, within a NVOP class, the various constituents did not present the same absorption rate.
Abstract: The lymphatic absorption of nonvolatile oxidation products (NVOP) formed during heating of fats was studied. Heated colza or soybean oils or synthetic triglycerides containing a definite aromatic or alicyclic fatty acid were fed to thoracic duct-cannulated rats. Tritium-labeled triolein was added to each dietary fat, as an internal standard, in order to calculate the percentage of lymphatic absorption of the ingested NVOP. Results show that 4% of the total polymeric acids, 53% of the total oxidized monomeric acids and 96% of the total cyclic monomeric acids were recovered in the lymphatic lipids. Gas liquid and quantitative thin layer chromatography of these 3 classes indicated that, within a NVOP class, the various constituents did not present the same absorption rate. The lymphatic absorptions of individual oxidized monomers were between 25 and 93%. Concerning the polymer fraction, the lymphatic recoveries were 1% (nonpolar dimers), 6.8% (polar dimers) and 12% (polar oligomers). Aromatic acids were absorbed to a lesser degree (50–60%) than cyclohexenic acids (91–98%).
TL;DR: Inability to form and accumulate docosapolyenoic fatty acids by D. magna might be related to their poor survival at reduced temperatures, and C. strenus directed a higher proportion of radioactivity into both oleic and docosahexaenoic acids upon cold exposure.
Abstract: Daphnia magna andCyclops strenus were maintained in aquaria containing sodium [1-14C] acetate and the effect of temperature on labeling of their lipids was investigated. Incorporation of radioactivity in total lipids was slowed by a factor of 4 in cold-exposed (5C) specimens compared to those incubated at 25 C. There was no significant difference in the distribution of label in the lipid classes of animals incubated at the two extreme temperatures. Decrease of the temperature from 25 to 5 C brought about a considerable reduction in the formation of palmitic and stearic acids and an increase in labeling of monounsaturated (18∶1) fatty acids inD. magna. Docosapolyenoic acids were absent from lipids of this crustacean.C. strenus directed a higher proportion of radioactivity into both oleic and docosahexaenoic acids upon cold exposure. In response to decrease of the temperature,D. magna formed a less unsaturated fatty acid population, as judged from dpm ratios of total saturated to total unsaturated fatty acids, thanC. strenus. Inability to form and accumulate docosapolyenoic fatty acids byD. magna might be related to their poor survival at reduced temperatures.
TL;DR: Evidence of (n−3) fatty acid enrichment in trout lipoproteins as well as in vitellogenin, egg lipovitellin and oil globule and a direct relationship between the two forms of plasma lipid transport and the two egg compartments suggest that there may be a relationship between EFA activity and the distribution of the EFA among the lipoprotein lipid fractions in vertebrates, irrespective of theEFA series.
Abstract: This paper describes evidence of (n−3) and particularly of 22∶6 (n−3) fatty acid enrichment in trout lipoproteins as well as in vitellogenin, egg lipovitellin and oil globule. Among the lipoproteins, HDL and LDL were the main forms of blood lipid transport, whereas phospholipids and cholesteryl esters are the preferential chemical carriers for (n−3) fatty acid transport. However, cholesteryl esters were less important as esterified fatty acid carriers than in man. Taken together with the data obtained in mammals, our results suggest that there may be a relationship between EFA activity and the distribution of the EFA among the lipoprotein lipid fractions in vertebrates, irrespective of the EFA series. Administration of an (n−3) fatty acid deficient diet for three months prior to trout spawning produced a significant increase in egg lipid content, primarily as a result of the increase of the oil globule composed almost exclusively of triacylglycerols. This diet decreased the 22∶6 (n−3), as well as the (n−3) fatty acid contents of lipoproteins, lipovitellin, vitellogenin and the oil globule. In contrast, the (n−3) fatty acid level was always higher in lipoproteins and lipovitellin than in the vitellogenin and the oil globule. Moreover, the relative levels of 22∶6 (n−3) and total (n−3) fatty acids were quite similar in lipoproteins and lipovitellin on the one hand, and in vitellogenin and the oil globule on the other. These findings suggest a direct relationship between the two forms of plasma lipid transport and the two egg compartments. During ovogenesis, dietary lipids seemed to be diverted from the adipose tissue and essentially deposited in the egg.
TL;DR: The mod i f i ed m e t h o d has been t e s t ed in this labora to ry on several g lycerol -e ther -der ived glyco-
Abstract: Tota l sugars in glycol ipids and p h o s p h o glycol ipids have general ly b e e n d e t e r m i n e d by the phenol su l fu r ic acid m e t h o d (1) e i the r on the i n t a c t l ipid or on water so lub le l ipid h y d r o lysates (2). This m e t h o d gives good resul ts w i th water -soluble glycol ipid hyd r o l y s a t e s and wi th i n t ac t acyl es ter glycol ipids (e.g., see ref. 3) b u t was f o u n d to give i ncons i s t en t and i r reproducible resul ts w h e n appl ied to i n t a c t glycol ipids of e x t r e m e l y ha loph i l i c bac te r ia (4) or m e t h a n o g e n i c bac te r i a (5), wh ich are der ived f rom C20-phytany lg lycero l d ie the r or C40glycerol t e t r ae the r , respect ively. I t was f o u n d t ha t m a i n t a i n i n g the t e m p e r a t u r e of the react i on w i th conc. sulfuric acid at 100 C was an i m p o r t a n t f ac to r in ob t a in ing r ep roduc ib le results. The p r o c e d u r e was t h e n mod i f i ed as fol lows: p ipe t an a l iquo t of l ipid so lu t ion or aqueous hyd ro ly sa t e con ta in ing 30-60 /ag sugar (as hexose ) in to a 35-ml Lewis-Benedic t sugar t u b e and evapora te the so lvent to dryness u n d e r a s t ream of n i t r ogen ; to the residue add 2 ml of wa te r and 1.0 ml of 5% p h e n o l so lu t ion , and mix gent ly b y vor tex ing , m a k i n g sure t ha t the fi lm of l ipid at the b o t t o m of t ube is undistu rbed . Add 5 ml of conc. sulfur ic acid wi th vo r t ex ing and t h e n h e a t for 5 m in in a bo i l ing wa te r ba th . V o r t e x the m i x t u r e br ief ly and al low it to cool for 30 min . Read the absorbance of the orange color at 490 n m against a reagen t b lank. Fo r ca l ibra t ion , use s t andards con ta in ing 20, 40 and 80 /ag of hexose or an appropr i a t e m i x t u r e of d i f fe ren t hexoses , depend ing on the k ind of hexoses and the i r mola r ra t ios in the or iginal lipid. Beer 's law ho lds in the range 0-80 /lg hexose ; 20 /~g glucose gives an abso rbance of 0 .112. The mod i f i ed m e t h o d has been t e s t ed in this labora to ry on several g lycerol -e ther -der ived glyco-
TL;DR: In this article, a possible mechanism is presented to account for sulfite-induced peroxidation of linoleic acid, suggesting that the reaction is mediated by the sulfite radical, which can be seen as a free radical mechanism.
Abstract: Sulfite initiated the peroxidation of linoleic acid and linolenic acid emulsions via a free radical mechanism. Peroxidation of these fatty acids required oxygen and sulfite and occurred with concomitant oxidation of sulfite to sulfate. In reaction mixtures containing linoleic acid, the formation of conjugated diene equaled the formation of hydroperoxide. In reaction mixtures containing linolenic acid emulsions, thiobarbituric acid reactive materials were also formed. Peroxidation was pH-dependent; peroxidation of linoleic acid proceeded between pH 4 and 7, but linolenic acid peroxidation was significant only if pH was below pH 6. The linoleic acid hydroperoxides thus formed were reduced and methylated to methyl hydroxystearate. Analysis of methyl hydroxystearate by gas chromatographymass spectrometry indicated that sulfite-induced peroxidation gave rise to the 9- and 13-hydroperoxy isomers. In addition to the hydroperoxides, sulfite adducts were detected. Hydroquinone, butylated hydroxytoluene and α-tocopherol effectively inhibited both sulfite oxidation and hydroperoxide formation. Conjugated diene formation also was inhibited by 4-thiouridine, suggesting that the reaction is mediated by the sulfite radical. No significant inhibition was observed with the addition of superoxide dismutase, catalase, or the hydroxyl radical scavengers, mannitol ort-butanol. A possible mechanism is presented to account for sulfite-induced peroxidation of linoleic acid.
TL;DR: A method is described for the purification of a number of phospholipids by preparative high performance liquid chromatography (HPLC) and chloroform/methanol mixtures are used as eluent systems, providing a wide polarity range to separate the classes of lipids.
Abstract: A method is described for the purification of a number of phospholipids by preparative high performance liquid chromatography (HPLC). Purification of digalactosyl-diglyceride from spinach and egg phosphatidylcholine, 1,2-dioleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine from its reaction mixture have been resolved. The lipid separation is performed on a polygosil column and the individual compounds are monitored directly by refractive index detection. Chloroform/methanol mixtures are used as eluent systems, providing a wide polarity range to separate the classes of lipids. The developed equipment can be used for columns between 10 and 50 cm long and 4 and 50 mm inner diameter. The flow rate could be varied between 1 and 100 ml/min and applied pressures between 10 and 450 bars.
TL;DR: The similar features of UV absorption, fluorescence, decrease of amino groups, and covalently bound phospholipid phosphorus of the various complexes suggest that they are formed by common type of reactions.
Abstract: Various peroxidized phospholipids were reacted with proteins under N2. In all cases, phospholipid is bound covalently to the proteins whose molecular size is increased. Both the amount of bound phospholipid and the increase in molecular size of the protein depends on the nature of the phospholipid. Ultraviolet (UV) absorption of the proteins is increased in qualitatively similar ways. Their difference spectra, which show a gradual increase in absorption from 400 nm toward shorter wavelength, differ from that of malonaldehyde-protein complexes. The various complexes of proteins and peroxidized phospholipids have similar fluorescence spectra showing two excitation maxima at 310–320 nm and at 340–350 nm, respectively, and emission maximum at ca. 400 nm. This is different from both fluorescence spectra of malonaldehyde-protein complexes and fluorescence spectra reported for proteins after reaction with peroxidized polyunsaturated fatty acids. Amino groups of the proteins are consumed in the reaction with peroxidized phospholipids. Blocking the amino groups decreases the binding of phospholipid considerably. Besides amino groups, other structures of the protein molecule react with the peroxidized phospholipids. The similar features of UV absorption, fluorescence, decrease of amino groups, and covalently bound phospholipid phosphorus of the various complexes suggest that they are formed by common type of reactions. The reactions seem to be different from those generally believed important between peroxidized lipid and protein. Important reacting species are compounds other than malonaldehyde.
TL;DR: In this paper, a molecular interpretation for the chain length dependent thermotropic behavior of saturated symmetric-chain phosphatidylcholine bilayers is proposed, where it is suggested that the bilayer interface region and conformationally inequivalent terminal ends of the fatty acyl chains perturb the packing associations of the rest of the hydrocarbon chains in the gel phase of bilayer.
Abstract: A molecular interpretation for the chain length dependent thermotropic behavior of saturated symmetric-chain phosphatidylcholine bilayers is proposed. It is suggested that the bilayer interface region and conformationally inequivalent terminal ends of the fatty acyl chains perturb the packing associations of the rest of the hydrocarbon chains in the gel phase of the bilayer. These perturbing effects, which are seen to increase with decreasing acyl chain length, have been quantitatively defined by a perturbation parameter, P. The thermodynamic parameters of the thermal phase transition of these phosphatidylcholines are found to be linearly correlated to P and these linear relationships can be used to predict the minimum number of carbon atoms in the acyl chain necessary in order for a bilayer phase transition to occur.
TL;DR: The trimethylsilyl ethers of the epimeric pairs of sterols with saturated side chains and a pair with two double bonds in the side chain were completely separated from each other by GLC.
Abstract: Paris of C-24 epimeric sterols have been very difficult to separate by physical emthods. We report here the partial or complete separation of the trimethylsilyl ethers of nine pairs of C-24 epimeric sterols by gas liquid chromatography on a glass capillary column coated with SP-2340. The trimethylsilyl ethers of the epimeric pairs of sterols with saturated side chains and a pair with two double bonds in the side chain were completely separated from each other by GLC. The epimeric pairs with a double bond at C-22 showed partial separation. The 24β-epimer with a saturated side chain eluted before the corresponding 24α-epimer. This order was reversed for pairs of C-24 epimeric sterol trimethylsilyl ethers containing a double bond in the side chain at C-22.
TL;DR: Pentane expired above basal levels during the following 4-hr period correlated with the amount of hepatic triglycerides determined at the conclusion of the experiment, indicating the etiology of ethanol toxicity is a complex and multifactorial system made up to many biological variables that influence lipid peroxidation.
Abstract: Weanling rats were fed one of 3 diets containing 0, 11 or 200 international units (IU) dl-α-tocopherol acetate/kg diet for 4 weeks. Following this period, the drinking water was replaced with an 18% solution of ethanol (v/v). An isocaloric D-glucose solution was substituted for the drinking water of a control group of rats fed the vitamin-E-deficient diet for 4 weeks. The 4 treatment groups were maintained on the diet and drinking regimen for 20 weeks. Basal levels of expired pentane were determined at weeks 0, 1, 3, 5, 7 and 9. Chronic ethanol consumption did not influence basal pentane production during the 9-week treatment. Basal levels of expired pentane were affected by dietary vitamin E. Rats supplemented with vitamin E had basal pentane levels less than one-half of the level of rats fed a vitamin-E-deficient diet (p<0.001). After 14 weeks of treatment, the 2 groups of rats fed a vitamin-E-deficient diet were administered p.o. an acute dose of 6 g of ethanol/kg body wt. Pentane expired above basal levels during the following 4-hr period correlated with the amount of hepatic triglycerides determined at the conclusion of the experiment. The etiology of ethanol toxicity is a complex and multifactorial system made up to many biological variables that influence lipid peroxidation. The appropriate choices of experimental designs and methods are important in examining the role of lipid peroxidation.
TL;DR: Wild oysters contained cholesterol, but cultivated oysters must be able to bioconvert phytosterols to cholesterol, concentrate dietary cholesterol, or synthesize cholesterol de novo.
Abstract: Wild oysters (Crassostrea virginica) contained cholesterol, 24-methyl-cholesta-5, 22-dienol, 24-methylenecholesterol, 22-dehydrocholesterol, 24-methylcholesterol, 24-ethylcholesterol, 24-norcholesta-5, 22-dienol, 24-ethylcholesta-5, 22-dienol and fucosterol The same species was cultivated on a defined diet ofThalassiosira pseudonana andIsochrysis sp The dietary algae were cultured and their sterol compositions were analyzed by gas chromatography and mass spectroscopyT pseudonana andIsochrysis sp had 24-methylenecholesterol and 24-methyl-cholesta-5, 22-dienol as their major sterols The sterol composition of the cultivated oysters revealed the predominance of cholesterol (19%), 24-methyl-cholesta-5, 22-dienol (21%) and 24-methylenecholesterol (46%) Therefore, oysters must be able to bioconvert phytosterols to cholesterol, concentrate dietary cholesterol, or synthesize cholesterol de novo
TL;DR: The amount of α-tocopherolquinone in rat liver has been reinvestigated comparing a conventional procedure including saponification and thin layer chromatography followed by high peformance liquid chromatography with the direct HPLC analysis of a total lipid extract.
Abstract: The amount of α-tocopherolquinone in rat liver has been reinvestigated comparing (a) a conventional procedure including saponification and thin layer chromatography followed by high peformance liquid chromatography (HPLC), with (b) the direct HPLC analysis of a total lipid extract. Recovery of added α-tocopherolquinone was quantitative with both procedures. In contrast to a recent report of 124 nmol/g in rat liver, we found no more than 1–4 nmol/g by procedure a and less than 1 nmol/g by procedure b.
TL;DR: Although no definitive statement can be made about the mechanism of release of arachidonate, the data are most easily interpreted as the result of the action of a phospholipase A2.
Abstract: Challenge of human neutrophils prelabeled with [3H]arachidonate and [14C] palmitate or [14C]-stearate with opsonized zymosan or the Ca2+ ionophores A23187 or Ionomycin caused the release of [3H], but not [14C], fatty acid. With the ionophores, but not zymosan, considerable conversion of the [3H] arachidonate to hydroxyeicosatetraenoates occurred. Although various isomers were recovered, the 5-hydroxyeicosatetraenoate appeared to be the major product. In these experiments, no [14C] products were detected such as lysophospholipid, diglyceride or monoglyceride. Although no definitive statement can be made about the mechanism of release of arachidonate, our data are most easily interpreted as the result of the action of a phospholipase A2.