The structures of the principal glycerolipids of pig liver

The lipid composition of pig liver has been determined. The principal glycerolipids, i.e., triglycerides, phosphatdyl choline, phosphatidyl ethanolamine and phosphatidyl inositol, were isolated and the positional distribution of fatty acids in each determined by stereospecific analysis procedures. Previous results for the triglycerides were confirmed, while the phospholipids were similar in structure to those found in most other animal livers. The triglycerides were separated into simpler molecular species by combinations of silver nitrate thin layer chromatography and high temperature gas liquid chromatography, but the proportions found did not agree well with those calculated assuming a 1-random, 2-random, 3-random arrangement. The phospholipids were hydrolyzed with phospholipase C and converted to diglyceride acetates that were fractionated into simpler molecular species by the same procedures as were used with triglycerides. Highly specific fatty acid combinations were found in molecular species, and these specificities were very similar to those reported in similar lipids from the livers of such disparate species as the rat and chicken.     

The lipid composition of selected tissues from a Mediterranean monk seal,Monachus monachus

The lipid composition of blubber, brain, muscle and heart from a Mediterranean monk sealMonachus monachus (an endangered species) were examined to allow comparisons with more common species of seals. Only neutral lipids (mainly triacylglycerols) were detectable in the blubber lipids, whereas polar lipids predominated in the heart and in the brain. Neutral and polar lipids comprised almost equal proportions in both liver and muscle. Choline glycerophospholipids (CGP) were the major polar lipids, followed by ethanolamine glycerophospholipids (EGP) in the liver, heart and muscle. Cerebrosides accounted for 28.8% of the brain lipids. All lipid classes of the liver contained high levels (31–47%) of polyunsaturated fatty acids (PUFA), with the exception of phosphatidylserine. The total proportion of n−6 PUFA exceeded that of n−3 PUFA in all lipid classes of the liver, due mainly to the high levels of 20∶4n−6. The highest level of 20∶4n−6 occurred in phosphatidylinositol, where it comprised 32.4% of the total fatty acids. The CGP and EGP of the brain contained lower levels of PUFA than those of the liver, muscle and heart. Alkenyl ethers accounted for 35.8% of the total long-chain moieties in brain EGP. The fatty acid composition of blubber triacylglycerols differed from those of the lipid classes from other tissues in that it had a very low ratio of n−6 to n−3 PUFA (0.3) as a result of a lower content of 20∶4n−6.     

Distinctive medium chain wax esters,triglycerides, and diacyl glyceryl ethers in the head fats of the pacific beaked whale,Berardius bairdi

Lipids were extracted from the mandibular fat body (jaw), the fatty forehead (melon), and the dorsal blubber of a Pacific beaked whale (Berardius bairdi) and separated into lipid classes by preparative thin layer chromatography. The head fats were mixtures of wax esters and triglycerides with a very small amount of diacyl glyceryl ether. The blubber fat contained 97% was ester and 3% triglyceride. Gas liquid chromatography (GLC) of the intact lipid classes indicated an unusually low C₂₆–C₃₀ range for most of the jaw and melon wax esters compared to the more normal C₃₂–C₄₀ molecules found in the blubber. Distinctive lower molecular weight C₂₄–C₄₀ triglycerides occurred in the head fats vs. the usual C₄₄–C₅₈ range in the blubber. Most diacyl glyceryl ethers were in the C₃₅–C₄₆ range, below the molecular weight of hexadecyldipalmitoyl glyceryl ether (C₄₈). GLC of the derived fatty acid methyl esters showed that the lower molecular weight neutral lipids in the head fats were due to high levels of iso-10∶0, n−10∶0, iso-11∶0, iso-12∶0, n−12∶0, and iso-13∶0 acids. The wax ester fatty alcohols and the alkoxy chains of the glyceryl ethers were mostly the C₁₄–C₂₀ chain lengths commonly observed in marine organisms. The distinctive medium chain neutral lipids in the jaw and melon fats of this whale may be related to the postulated acoustical role of these tissues in echolocation.     

The distribution of 17 carbon fatty acids in the liver of a child with propionicacidaemia

A child with propionicacidaemia due to a defective propionyl CoA carboxylase activity, accumulated odd number fatty acids in his liver. Seventeen carbon saturated and monounsaturated acids both represented 2% to 3% of the total liver fatty acids. The monounsaturated acid is demonstrated to be heptadec-9-enoic acid. The distribution of the 17 carbon saturated and monounsaturated acids throughout the major lipid classes is described. Enzymic degradation of lecithins and triglycerides is used to establish the positional specificity of esterification of these two fatty acids. The results indicate that when the only difference between two fatty acids, present in similar concentrations, is a single double bond, highly specific esterification patterns are retained.     

The selective utilization of diglyceride species into maize triglycerides

The maize triglycerides were resolved into species by silver nitrate thin layer chromatography. The distribution of the fatty acids among the 1, 2 and 3 positions of each triglyceride species was determined by stereospecific analysis. From these data the relative amounts of each positional isomer were calculated. The results indicate that esterification of the fatty acids at each position proceeds with a specificity that is correlated with the composition of the other positions of the triglyceride.     

Effect of methyl 2-hexadecynoate on hepatic fatty acid metabolism

Normal and hepatoma bearing rats were fed a low level of methyl 2-hexadecynoate in a low fat diet for one month. The effect of the acetylenic acid on lipid metabolism as derived from mass analysis of lipid classes, fatty acids and positional monoene isomers isolated from the major lipid classes of liver and hepatoma has been assessed. Methyl 2-hexadecynoate caused a 25% decrease in body weight and the appearance of essential fatty acid deficiency symptoms within one week. Non-tumor-bearing animals contained a seven-fold increase in all neutral lipid classes, except cholesterol, while host animals did not contain fatty livers. The apparent protective effect of the host animal by the hepatoma also resulted in only marginal changes in the fatty acid and positional monoene isomers from host liver and hepatoma lipids. In contrast to host liver and hepatoma, methyl 2-hexadecynoate caused a massive accumulation of palmitate and hexadecenoates with a concomitant decrease in stearate and octadecenoates in most of the lipid classes from non-tumor-bearing animals. These changes were accompanied by a shift from the higher molecular weight triglycerides to lower molecular weights corresponding to carbon number 48. The high concentrations of hexadecenoates consisted predominantly of the Δ9 isomer. Despite the high concentrations ofcis Δ9 hexadecenoate, precursor ofcis Δ11 octadecenoate (vaccenate), total vaccenate levels of the five major lipid classes were lower than control values. All of these data strongly suggest that long-chain 2-ynoic acids inhibit elongation of saturated and monoene fatty acids.     

Isovaleroyl triglycerides from the blubber and melon oils of the beluga whale (Delphinapterus leucas)

The fatty acid compositions of the blubber and melon oils from the beluga whale (Delphinapterus leucas) have been determined by gas liquid chromatography (GLC). The melon oil contains a high level (60.1 mole %) of isovaleric acid, substantial amounts of long chain branched acids (16.9%), and very little polyunsaturated material (0.5%). The blubber oil contains less isovaleric (13.2%), fewer long chain branched acids (2.7%), and appreciable amounts (10.9%) of the polyunsaturated acids typical of marine oils. The blubber and melon oils were also examined for lipid class composition by thin layer chromatography on silicic acid, direct GLC of the hydrogenated oil, and gel permeation chromatography. Both oils are composed almost entirely of triglycerides, which can be separated chromatographically into molecules containing 0, 1 and 2 isovaleric acid moieties. No triisovalerin could be detected. The blubber oil contains 68.9 mole % normal triacyl-, 24.2% diacyl-monoisovaleroyl-, and 7.0% monoacyl-diisovaleroyl-triglycerides (acyl=long chain acid). Monoacyl-diisovalerin constitutes 86.7 mole % of the melon oil. This unusual compound may play a role in the echolocation system of the beluga whale.     

Effect of hepatoma on host liver,heart and lung lipids as tumor growth progresses

A large group of rats was transplanted with hepatoma 7288CTC and 4 animals were sacrificed at 3-day intervals for four weeks. Lipid class concentrations, fatty acid class compositions, and the distribution ofcis octadecenoate positional isomers in the major lipid classes were determined for heart, liver and lung at each time period. The hearts of host animals decreased in dry weight as hepatoma growth progressed. At day 30, heart weights were less than two-thirds of initial weights. Lipid class concentrations changed in all three tissues: cholesterol and free fatty acids increased in liver; triglycerides and cholesterol decreased and then increased in heart; and cholesterol, triglycerides and PC decreased in lung as tumor growth progressed. Hexadecenoate percentages exhibited a progressive decrease in all the lipid classes of heart and liver. Although total octadecenoate percentages showed only minor changes, oleate concentrations generally increased and vaccenate levels decreased in heart and liver lipids as tumor growth progressed. Palmitoleate, precursor of vaccenate, exhibited decreased concentrations early that resulted in decreased vaccenate levels. Decreased palmitoleate concentrations suggest inhibition of the Δ9 desaturase system, but normal oleate concentrations complicate this interpretation. Most of the changes in the lipids were detectable 3–6 days after transplantation, indicating the hepatoma affects the lipid metabolism of the host animal early and well in advance of nutritional stresses.     

Effect of eicosatetraynoic acid on liver and plasma lipids

Groups of rats were fed a fat-free diet supplemented with 0.5% safflower oil (control) or the control diet containing 0.5% of 5,8,11,14-eicosatetraynoic acid (TYA). Blood was collected weekly and plasma lipids analyzed. After 4 weeks, the animals were killed and the liver lipids were analyzed in detail. The acetylenic fatty acid perturbed plasma neutral lipid and phospholipid class concentrations and reduced growth rates. Liver triglyceride concentrations were reduced dramatically in the TYA fed animals, suggesting interference with complex lipid synthesis. Plasma and liver triglycerides were shifted to higher molecular weight species suggesting that TYA affected fatty acid metabolism. The phospholipids showed an accumulation of 18∶2 and a fall in 20∶4 percentages indicating an inhibition in the conversion of linoleate to arachidonate. All major lipid classes exhibited an increase in 18∶1 levels. Analysis of the octadecenoate positional isomers indicated the proportion of oleate increased substantually in all lipid classes whereas vaccenate proportions had fallen dramatically. All of the data collectively suggest that TYA inhibits the elongation of unsaturated fatty acids. A group of rats bearing hepatoma 7288CTC were also fed the TYA diet. Host liver lipids were affected by TYA similar to normal TYA fed animals, but the effects on hepatoma lipids were marginal.     

Geometrical and positional isomer content of the monounsaturated fatty acids from various rat tissues

The percentage distribution of the geometrical and positional isomers in the hexadecenoates and octadecenoates isolated from triglycerides, phosphatidylch olines, and phosphatidylethanolamines of brain, heart, kidney, liver, lung, muscle, spleen, and adipose tissues from normal rats maintained on a laboratory diet has been determined. All of the octadecenoates and most of the hexadecenoates from the lipid classes of all the tissues consisted of more than 95%cis isomers. Generally, palmitoleic was the predominant hexadecenoate, but many of the tissue phospholipids contained relatively high percentages of the Δ6 and Δ7 isomers. Oleate and vaccenate were the predominant octadecenoates in all tissues. Except for brain and adipose tissues, the oleate to vaccenate ratios differed for each lipid class, as well as between most tissues. In contrast to the monoenes of the phospholipids, the triglyceride monoenes exhibited the same approximate: percentage composition; percentage of geometrical isomers; and percentage distribution of hexadecenoate and octadecenoate positional isomers. These data add to our basic information about the percentage distribution of geometrical and positional isomers of naturally occurring unsaturated fatty acids in the major lipid classes of various normal tissues. Some new concepts were advanced as possible explanations to some of the observed positional isomer distributions.     

Lipids of freshwater dolphinSotalia fluviatilis: Comparison of odontocete bioacoustic lipids and habitat

The melon and jaw lipids of the freshwater dolphinSotalia fluviatilis are composed mainly of isovaleroyl wax esters and diisovaleroyl triglycerides. The blubber fat contains only a trace of wax ester and is mostly tri- (long chain) and monoisovaleroyl triglycerides. Detailed gas liquid chromatographic analyses of the intact wax esters and triglycerides and of the derived fatty acids and fatty alcohols indicate common compositional patterns in the wax esters and triglycerides of the respective head lipids. Both odd and even long chain (C₁₂−C₁₆) iso-structures are prominent in the melon and jaw lipids, but only higher odd chain length iso-acids are major components in the blubber.Sotalia fluviatilis (family Delphinidae) andInia geoffrensis (family Platanistidae) share the same freshwater habitat in the upper Amazon River, and both utilize echolocation to navigate and to find food. Comparison of their respective bioacoustical lipid compositions shows distinctive types of head fats,Sotalia being rich in iso-5∶0 andIndia lacking iso-5∶0. This indicates that isovaleric acid per se has no obligatory role in dolphin echolocation.     

Effect of dietary cyclopropene fatty acids on the octadecenoates of individual lipid classes of rat liver and hepatoma

The effect of dietary cyclopropene fatty acids on the concentration of octadecenoate chain positional isomers in individual lipid classes of normal liver, host liver, and hepatoma 7288CTC has been determined. The data revealed the following: (a) Saturated and monoene fatty acid percentages of liver phosphatidylcholines and phosphatidylethanolamines werenot affected, but the percentage of saturated fatty acids of the triglycerides and cholesteryl esters was increased while the monoene percentages decreased. (b) Oleate to vaccenate percentage ratios, previously shown to be characteristic of individual lipid classes, were completely disrupted. (c) Oleate concentrations of the two major liver phospholipids were elevated, and vaccenate levels were dramatically reduced. (d) Cyclopropene fatty acids appear to inhibit monoene elongation. (e) The elevated concentrations of oleate indicate that an alternate route of oleate biosynthesis must exist if the Δ9 desaturation is inhibited by cyclopropene fatty acids as reported previously. (f) In contrast to liver, oleate and vaccenate concentrations in hepatoma were not affected by the dietary cyclopropene fatty acids.     

Hepatoma,host liver,and normal rat liver neutral lipids as affected by diet

Groups of normal and hepatoma (7288CTC) bearing rats were maintained on normal chow and fat-free diets for 4 weeks. Normal liver, host liver, and hepatoma neutral lipids were examined in detail and compared. Water content, unaffected by diet was: hepatoma, 82 percent; host liver, 71 percent; and normal liver, 67 percent. The fat-free diet had no effect upon the hepatoma neutral lipids but elevated the triglyceride level in normal and host liver, shifted the triglyceride carbon number distribution to lower mol wt, and elevated the percentage of monoenoic acids in triglycerides and cholesteryl esters. Host triglyceride concentrations were ca. half, and cholesterol levels were reduced moderately relative to normal liver values. Hepatoma cholesterol levels were higher and triglyceride concentrations lower than normal and host liver values. Hepatoma triglycerides differed dramatically from liver and were characterized by increased concentrations of high mol wt species and a fivefold increase in the percentage of C-20 and C-22 fatty acids. The percentage of C-20 and C-22 fatty acids in hepatoma cholesteryl esters also increased ca. fivefold relative to liver. The data indicate that the systems that regulate triglyceride and cholesteryl ester fatty acid composition in liver do not control the compositions of these lipid classes in this hepatoma. The unchanged high level of essential fatty acids in the hepatoma lipids from the fat-free fed animals demonstrates the hepatoma's ability to absorb and conserve specific fatty acids.     

Composition of wax esters,triglycerides and diacyl glyceryl ethers in the jaw and blubber fats of the Amazon River dolphin (Inia geoffrensis)

The lower jaw fat of the Amazon River dolphinInia geoffrensis contains 52.8% wax ester, 44.7% triglyceride and 2.5% diacyl glyceryl ether, while its dorsal blubber fat is >98% triglyceride. Examination of the intact lipids, the derived fatty acids and the derived fatty alcohols by gas chromatography reveals that the blubber triglycerides show characteristics of freshwater fish fats, but the jaw fat lipids have several distinctive features. Jaw fat wax esters, triglycerides and diacyl glyceryl ethers are all rich in C₁₀, C₁₂ and C₁₄ fatty acids and contain no polyunsaturated acids. The fatty alcohols in the wax esters are over 90% saturated. The major carbon numbers in the jaw fat triglycerides (C₃₈–C₄₆) are considerably lower than those of the blubber triglycerides (C₄₈–C₅₄). The possible adaptation of the jaw lipids for use in the underwater echolocation process of this dolphin is discussed.     

The structure of rat liver triglycerides

The fatty acid compositions at the 1-, 2-, and 3-positions³ of rat liver triglycerides were determined by using pancreatic lipase and diglyceride kinase. The distribution of acids between the 1- and 3-positions is not random; rather each position has a characteristic composition. The relative abundance of species and positional isomers in the triglyceride mixture was predicted by using values from the stereospecific analysis and assuming that the composition of each position is independent of the other two. The total triglyceride was resolved into species by using TLC with silver nitrate and Silica Gel G, and the relative amounts corresponded closely with those predicted on the basis of this assumption. The major species were isolated, and the distribution of their fatty acids among the three glyceride positions was determined. From these data the relative amount of each positional isomer was calculated. The results indicate that the esterification of fatty acids at each position proceeds with a specificity that is not correlated with the composition of the other positions with the molecule. The relative abundance of the different liver triglyceride species is also found to be related in part to the composition of the 1,2-diglyceride units found in the lecithins of this tissue. Presented at the AOCS Meeting, Philadelphia, October 1966.     

The Structure of the glycerides of pistachio kernel oil

Pistachio kernel oil has been analyzed by separating the triglycerides according to their degree of unsaturation by means of thin layer chromatography on silica gel plates impregnated with silver nitrate. The total fatty acids and the fatty acid on position 2 of each individual triglyceride were determined. The distribution of oleic acid on the different positions of triglycerides varies according to the unsaturation of these triglycerides. Oleic acid in the case of the less unsaturated triglycerides locates in the 2-position, and, as the degree of unsaturation increases due to linolenic or linoleic acids, it tends to be on external positions. Linoleic and linolenic acids usually are esterified in the middle position.     

Animal endogenous triglycerides: III. Swine,rat and chicken liver: Comparison with adipose tissue

The endogenous triglycerides of swine, rat and chicken livers were fractionated by silver ion thin layer chromatography and the resulting fractions were analyzed for their fatty acid composition and distribution. Whereas the endogenous triglycerides of swine adipose tissue differ markedly from those of rat and chicken adipose tissue in the location of the major fatty acids, the liver triglycerides of the three species are quite similar. They also resemble rat and chicken adipose triglycerides.     

Lipid components and enzymatic hydrolysis of lipids in muscle of Chinese freshwater fish

The lipid and fatty acid composition of muscle of 10 species of freshwater fish obtained from a market of Shanghai City was examined. Total lipids (TL) ranged over 0.9–4.7% of muscle for all samples. The content of triacylglycerol (TG) in muscle ranged over 0.2–3.4% and that of polar lipids (PL) was 0.5–1.3%. Differences of TL content were dependent on TG contents. The predominant important fatty acids (>10% of the total fatty acids in TL) were 16∶0 and 18∶1n−9 with some 16∶1n−7, 18∶2n−6, and 22∶6n−3. The polyunsaturated fatty acids (PUFA) content was 10.2–43.4%, and especially Chinese sea bass contained above 20% of 22∶6n−3 in the total fatty acids. There were higher levels of PUFA such as 20∶5n−3 and 22∶6n−3 in PL than in neutral lipids. Muscle of the silver carp was stored at 20°C, and changes of lipid classes during storage were examined. Free fatty acids increased, and PL decreased during storage. This phenomenon was inhibited by heating the muscle, suggesting that lipid hydrolysis by phospholipase occurred in silver carp muscle.     

Wax esters and triglycerides as storage substances in seeds of Buxus sempervirens

The seeds of the evergreen Buxus‐tree, Buxus sempervirens, contain a yellowish oil which represents up to 42% of the dry weight. The oil consists, in comparison to the lipids of jojoba fruits (Simmondsia chinensis), of only 3.6% wax esters. 95% of the oil consist of triglycerides, the typical storage substances of oil fruits. Phospholipids occur with 0.4% and glycolipids with 0.13%. The fatty acid patterns of these lipids correspond to the typical fatty acid compositions of the respective lipid classes. In the wax esters monoenoic fatty acids and saturated fatty acids with 16 and 18 carbon atoms prevail. The glycolipid and phospholipid fractions are characterized by a high portion of dienoic and monoenoic as well as saturated fatty acids having 16 and 18 carbon acids.     

Tissue culture of cocoa bean (Theobroma cacao L.): changes in lipids during maturation of beans and growth of cells and calli in culture

Callus cultures ofTheobroma cacao L., initiated from explants of immature cocoa bean cotyledons, contained 5.3%–6.4% lipids (dry wt basis). The major fatty acids were palmitic, oleic and linoleic acids. Cell suspensions contained 5.7–7.7% total lipids which had a higher polyunsaturated fatty acid content than total lipids of the calli. Phospholipids and glycolipids were the predominant lipid classes of calli and cell suspensions. Immature cocoa beans at early stages of development contained much higher polyunsaturated fatty acids, higher polar lipids and lower triglycerides than did mature ripe beans. Ripe cocoa beans contained 54% total lipids of which 96.8% where triglycerides. The fatty acid composition of total lipids of calli and cell suspensions were similar to those of the immature cocoa beans.