The lipids of human pancreas with special reference to the presence of fatty acid methyl esters

Total lipids were extracted from human pancreas with chloroform-methanol, chloroform-methanol following acidification, and benzene. A similar proportional amount of total lipid was obtained by each procedure. Regardless of the method of extraction (i.e., whether or not methanol was present), a small proportion (about 1%) of the total lipid was found to consist of fatty acid methyl esters. Triglycerides constituted the major fraction (about 80%) of the pancreatic lipids; in addition to methyl esters, the remaining lipids comprised free fatty acids, phospholipids, cholesterol esters, and traces of free cholesterol. In general, each class of lipid had a similar over-all fatty acid composition with palmitic and oleic acids as predominant components. The methyl esters had a relatively high content of linolenic acid, and the free fatty acids contained a notably high proportion of palmitic acid, in each case accompanied by a corresponding decrease in the proportion of oleic acid present.     

Kurzfristige Fütterungsversuche mit Methylestern dimerer Fettsäuren

Short-Time Feeding Tests with Methyl Esters of Dimeric Fatty Acids Fatty acid methyl esters ex safflower oil were polymerised at high temperature and separated by distillation. Feeding experiments with rats at a level of up to 50 cal-% in the food showed the highest degree in growth retardation with those fractions which contained esters of dimeric fatty acids. Esters of dimeric fatty acids of well defined structure, were fed to mice per os to determine acute toxicity. With the compounds applied the toxicity was far higher than 20 ml/kg body weight. After feeding radiocarbon labelled dimeric fatty acid esters, it could be shown that a high percentage of the material fed was excreted. However, a small amount is metabolised since ¹⁴CO₂ was observed in the exhaled air, and radioactive monomeric fatty acids were found in the body fat. Finally a small amount of the labelled dimeric fatty acids fed to the rats was recovered from the body fat indicating direct incorporation.     

Ernährungsphysiologische Wirkung unterschiedlicher Gemische von Öl-, Linol- und Linolensäure bei wachsenden Schweinen. 2. Einfluß auf Depotfette und Blutlipide

Physiological Effect of Various Mixtures of Oleic, Linoleic and Linolenic Acids on Growing Pigs: 2. Influence on Depot Fats and Blood Lipids At the end of the feeding trials described extensively in the first contribution, from all animals saddle bacon and leaf fat as well as serum lipids have been investigated on effects of the various food fats. Earlier results have been confirmed according to which the increased supply of unsaturated fatty acids results in an increase of the content in depot fat and in a decrease of palmitic and stearic acid. The storage of linoleic and linolenic acids is linked to the consumed amount of these acids in a linear way. Some hints have been found for the occurrence of yellow fat desease that besides the deficiency of vitamin E an enzyme activating effect of higher amounts of linolenic acid may be responsible. Furthermore the attacked animals showed a linear dependence of the fat content in the yellow tissue from its peroxide value. As well linolenic acid as oleic acid led to a significant decrease of the serum triglycerides. Besides, linolenic acid lowered the content of serum cholesterol, whereas linoleic acid caused a significant increase of the HDL content.     

Phosphatides isolated from seeds of commercial and experimental safflower varieties

Studies on phosphatides from several safflower varieties show the following five major results. The total phosphatide contents of the various safflower seeds are quite similar (0.48% for a commercial and 0.58% for a brown-striped variety). The same three major and one minor phosphatides were present in all varieties: phosphatidyl choline (PC), phosphatidyl ethanolamine (PE), phosphatidyl inositol (PI) and phosphatidyl serine (PS). The amounts of these lipids present in the crude phosphatide mixture were quite similar in all varieties tested (}36% for PC, }15% for PE, }23% for PI, and less than 2% for PS). The fatty acid composition of the phosphatides of UC-1 high oleic safflower is very different from that of the other varieties, but it reflects the composition of the corresponding oil triglycerides as far as the major acid is concerned. All other safflower seed phosphatides investigated have linoleic acid as the major fatty acid constituent. A simple and very sensitive color test has been found which can differentiate phosphatides of the high linoleic from the high oleic type. W. Utiliz. Res. Dev. Div., ARS, USDA.     

Ernährungsphysiologische Wirkung unterschiedlicher Gemische von Öl-, Linol- und Linolensäure bei wachsenden Schweinen 5. Einfluß auf die Lipide des Herzmuskels

Physiological Effect of Various Mixtures of Oleic, Linoleic and Linolenic Acids on Growing Pigs: 5. Influence on the Lipids of the Heart Muscle Samples of heart muscular tissue of all 72 animals of the feeding trial, which is extensively described in the 1. communication, were investigated for the total lipid content and its composition. A significant effect of the different feeding fat compositions on total lipid content could not be established. As well as for the liver lipids a metabolic effect on linolenic acid and in a lower degree of oleic acid doses on the formation of arachidonic acid can be found, which is in the investigated lipid classes obvious in the metabolic very active free fatty acids and in the phospholipids. The lipid class composition of the total lipids is influenced for phospholipids and triglycerides by high linolenic acid doses. The relative composition of the phospholipids as such changes only slightly by different exogenous fatty acids.     

Massenspektrometrische Identifizierung von verzweigtkettigen Fettsäuren und Alkoholen aus Bürzellipiden

Mass Spectrometric Identification of Branched Chain Fatty Acids and Alcohols from Preen Gland Lipids The preen gland lipids of some birds were isolated, the waxes separated and resolved into fatty acid and alcohol fractions. The alcohols were oxidised with chromic acid to form the corresponding fatty acids. After methylation with methanolic HCl, the fatty acid methyl esters were investigated by capillary gas chromatography-mass spectrometry. The fatty acids possess mainly mono-, di- and trimethyl branched structures, the branching positions being located preferentially on C–2/–3/–4/–6, C–2,4/–2,6/–2,8/–3,7 C–2,4,6/–2,6,10 and C–6/C–10 or C–14. The mass spectrometric fragmentations which are significant for the structure elucidation of these fatty acid methyl esters are discussed in detail. The investigations indicate a correlation between the composition of the birds to defined orders of the natural system (chemotaxonomy).     

Fatty acid synthesis in rat testes injected intratesticularly or incubated with 1-14C acetate

Fatty acid synthesis was studied in testes of young and adult rats either injected intratesticularly or incubated with 1-¹⁴C acetate. The pattern of¹⁴C incorporation into lipids and individual fatty acids in the two age groups was similar but results obtained with intratesticular injection differed considerably from those obtained in the in vitro studies. In the former more than 70% of the¹⁴C incorporated in total lipids was in phosphatides, with about 15% in triglycerides and only minor amounts in cholesteryl esters and free fatty acids. Most of the¹⁴C incorporated into total fatty acids was in saturated acids (predominantly 16∶0). A small amount of¹⁴C was in the higher polyenes and there was a progressive increase with time after acetate injection in the¹⁴C content of 22∶5 W6. In testes incubated with 1-¹⁴C acetate, the phosphatide, triglyceride, and free fatty acid fractions had similar amounts of¹⁴C. In the total fatty acid fraction about 40% of the incorporated¹⁴C was in saturated acids (predominantly 14∶0 and 16∶0) and about 50% in the higher polyenes. Twenty carbon polyenes and 22∶5 W6 had significant¹⁴C incorporation, but most of the¹⁴C was in 22∶4 W6. About 80% of the¹⁴C in the latter compound was in the carboxyl carbon, indicating its origin from endogenous 20∶4 W6 elongated by the added 1-¹⁴C acetate used as substrate. The¹⁴C 22∶4 was present predominantly in the triglyceride and phosphatide fractions with minor amounts in other lipids.¹⁴C-labeled compounds of retention time greater than 22∶5 were also present in all lipid fractions. Presented at the ISF-AOCS World Congress Chicago, September 1970.     

Composition of the neutral and phospholipid fractions from ginkgo nuts (Ginkgo biloba) and fatty acid composition of individual lipid classes

The purified lipid fraction (1.26% on the wet weight basis) from the nuts ofGinkgo biloba was found to be 90.6% neutral lipids, 7.5% polar lipids, and a very small amount of glycolipids. Main fatty acids in the triglyceride fraction were oleic and linoleic acids, and those in the phospholipid fraction were palmitic acid in addition to these unsaturated acids. The enzymic hydrolysis of the triglyceride and individual phospholipid fractions showed that only the triglyceride and phosphatidylcholine fractions contained relatively large amounts of unsaturated acids in their β-positions. The gas liquid chromatography-mass spectrometric analysis of the fatty acids of the steroid ester fraction indicated the presence of lignoceric, cerotic, montanic, and melissic acids as well as a lactone and compounds suspected to be phenolic acids containing long chain diols.     

Synthesis of Phytosteryl Esters by Using Alumina-Supported Zinc Oxide (ZnO/Al<Subscript>2</Subscript>O<Subscript>3</Subscript>) from Esterification Production of Phytosterol with Fatty Acid

The feasibility of zinc oxide-catalyzed esterification of natural phytosterols with oleic acid was investigated well by a chemical process. The influences of various reaction parameters were evaluated. Basic solid zinc oxide is the most desirable catalyst due to its high selectivity (more than 90%), reusability, activity and less corrosivity, whereas sterol selectivity with other catalysts, such as H₂SO₄, NaHSO₄ and NaOMe, did not exceed 80%. Further results showed that during zinc oxide-catalyzed synthesis, the nature of the acyl donor was of paramount importance with direct esterification with fatty acids, which gives better results with higher conversion rate selectivity and more mild reaction conditions than transesterification with methyl esters. The substrate molar ratio of 2:1 (oleic acid/phytosterol) was optimal. Other parameters such as optimal catalyst load (0.5%) and temperature (170 °C) showed a maximum production of steryl esters close to 98% after 8 h. It was also found that the amount of trans fatty acid formed in esterification was low, and the trans fatty acid content (%) in the phytosterol oleate ester fraction (3.26%) was much lower than that in free oleic oil (7.35%), which suggested that fatty acids in esters were more stable than free fatty acids regarding the combination with sterol. Immobilized ZnO could be a promising catalyst for replacing homogeneous and corrosive catalysts for esterification reactions of sterol.     

Wechselwirkungen zwischen Aromastoffen und Lipiden 1. Mitteilung: Sorption einiger leichtflüchtiger Stoffe an reine Lipide

Interactions Between Aroma Substances and Lipids 1. Sorption of Some Volatile Substances in Pure Lipids Ethyl acetate, n-hexane, ethanol, and acetone are sorbed much better by liquid lipids than by solid ones. The sorption capacity of liquid lipids increases in the order triglyceride, free fatty acid, fatty acid methyl ester, and also with decreasing chain length of the fatty acid residues. Oleic acid derivatives sorb more than stearic acid ones. The sorbed amounts decrease in the order ethyl acetate, ethanol or hexane, acetone. This holds for the sorption of small amounts (some mmol/kg) measured by the retention volumes in gas chromatography, and for the sorption of greater amounts, which was measured by gravimetry. The sorption is a physical one. The sorption heats are 25–35 KJ/mol. Stronger binding is observed between phenol and esters and between n-butylamine or pyridine and free acids.     

Beiträge zur Kenntnis der Lipoid-Zusammensetzung im menschlichen Blutserum bei gestörtem Fettstoffwechsel

Contribution to the Knowledge of Lipid Compositions of Human Blood Serum during Disorder in Fat Metabolism The lipids of human blood serum were investigated with the help of thin-layer chromatography. In the blood serum of patients with disturbed fat metabolism a further fraction was observed between the fractions of triglyceride and cholesterol ester. The authors concluded that this fraction, obtained after the extraction of the lipid with a methanol containing solvent mixture, consists of methyl esters of fatty acids.     

Zur fütterungsbedingten Variation des Milchfettes der Kuh unter besonderer Berücksichtigung von Regulationsmechanismen beim Fettstoffwechsel

Variations of Cow's Milk Fat as Affected by Feeding with Special Consideration of Regulation Mechanisms of Fat Metabolism Milk fat composition is highly affected by the conditions of feeding, which again may have considerable consequences for the quality of several dairy products. In order to establish possible variations in physical and chemical properties of the milk fat as depending on the nutritional status of the cow, a small herd of cows was successively subjected to different defined feeding conditions (barn feeding, pasture feeding, energy deficit). The investigations indicated that from barn feeding to pasture feeding to energy deficit the proportions of oleic acid and of long chain triglycerides increased and the proportions of short and medium chain fatty acids and triglycerides decreased. In spite of highly differing fat compositions relatively constant values for the viscosity and the average triglyceride molecular weight were obtained; also various characteristics from the melting and solidification curves were nearly identical. The solid/liquid ratios approached at higher temperatures. These results point to the existence of regulation mechanisms, in the course of which the flow and melting properties are kept within the required narrow ranges by an opposite behaviour of the proportions of short chain fatty acids and oleic acid. With pasture feeding, compared with barn feeding, all oleic acid isomers and linoleic acid increased, with energy deficit the proportions of these acids are at the low level of barn feeding. These results as well as the continuous decrease of the cholesterol content from barn to pasture to energy deficit are explained on the basis of the different pathways of fat metabolism; deficit are explained on the basis of the different pathways of fat metabolism; furthermore the proportions of trans C18: 1 acids are discussed in connection with the milk fat content. The milk fat globules are particularly large and unstable at the period of energy deficit. Consequently, quality deterioration of whipping cream (creaming, plug formation) and other dairy products (lipolysis) can be expected.     

The triglycerides of sable fish (anaplopoma fimbria). II. fatty acid distribution in triglyceride fractions as determined with pancreatic lipase

Sable fish muscle lipids were fractionated on a silicic acid column with mixtures of chloroform and methanol as eluting solvents. Three main peaks containing only triglycerides were isolated; 11 additional peaks contained phosphorous. Each of the 3 triglyceride peaks was separately fractionated into 300 fractions on silica gel columns impregnated with silver nitrate. Mixtures of petroleum ether and ethyl ether were the eluting solvents. About 25 distinct fractions were isolated from each column. The fractions were characterized for fatty acid content by gas chromatography of the methyl esters. The results showed that the fractionation did not depend upon the presence of single fatty acids but upon total unsaturation. Fatty acid distribution within each fraction was determined with the use of hog pancreatic lipase, followed by thin-layer chromatography and gas chromatography. Presented at the AOCS Meeting in Houston, Texas, 1965.     

Hydrierung von Lipiden als Hilfsmittel zur Identifizierung und Quantifizierung von Phosphatiden aus Membransystemen des Herzmuskels

Hydrogenation of Lipids for Identification and Quantification of Phosphatides from Pellicle Systems of Cardiac Muscle. It was the aim of our research to show that hydrogenation of lipids is an auxiliary technique in phospholipid analysis of cardiac membranes. This is of interest if a preliminary overview on lipid fractions containing highly unsaturated fatty acids is needed. The fatty acids and the diglycerides from phospholipids were hydrogenated according to the procedure described by Appelqvist (A simple and convenient procedure for the hydrogenation of lipids on the micro- and nanomole scale, J. Lipid Res. 13 (1972), 146) with platinum oxide as a catalyst. The lipids (fatty acid methyl esters or acetylated diglycerides) were taken to dryness in a test-tube under nitrogen and flushed with hydrogen. The catalyst, suspended in methanol was injected through a septum. For identification purposes thin-layer chromatography on silica gel and on silica gel impregnated with silver nitrate was combined with gas chromatography before and after hydrogenation. After hydrogenation the fatty acid profile is much simpler and the fatty acid methyl esters can easily be differentiated from dimethyl acetals, as the latter are more volatile. Diacylglycerides and alkenylacylglycerides were also separated by thin-layer chromatography in individual subclasses before they were analysed by gaschromatography. Hydrogenating the lipids makes it possible to circumvent in part difficulties which arise often with polyunsaturated fatty acids. As the chain length of C20 and C22 are mainly represented by C20:4 , the arachidonic acid and C22:6 the docosahexaenoic acid, both fatty acids can be assessed after hydrogenation. The fatty acid profile of phosphatidylcholine and phophatidylethanolamine of cardiac muscle from rat, guinea pig and pig was determined. Each sample was analysed before and after hydrogenation. The fatty acids with the same chain length were summed up and compared to the corresponding chain length after hydrogenation.     

Effects of dietary triglyceride on the properties and lipid composition of plasma lipoproteins: Acute experiments in rats fed safflower oil

Male rats were administered 1.5 ml safflower oil by gastric intubation 0, 4, and 8 hr after a 16 hr fast. Plasma, liver, and adipose tissue were collected 16 hr after the last fatty meal. Rats fasted for 16 hr served as controls. Following fat feeding, the fatty acid composition of the very low density lipoprotein, triglyceride, and hepatic triglyceride were similar, as were the percentages of 18:2 in the very low density lipoprotein and hepatic cholesteryl esters. The phospholipids of liver and plasma lipoproteins were similar in the control groups, except that more 16:0 was present in the plasma lipoproteins. After fat feeding, the plasma lipoproein phospholipids were enriched with 18:2 more than were the hepatic phospholipids. Furthermore, the percentage of 18:2 in phospholipid was much less than in triglyceride or cholesteryl esters. Clearly, esterified lipids of liver and plasma lipoproteins (very low density lipoprotein, low density lipoprotein, and high density lipoprotein), and to a lesser extent, adipose tissue, were enriched with 18:2 derived from dietary triglyceride fatty acid even 16 hr after the terminal meal. A major proportion of the very low density lipoprotein isolated by ultracentrifugation in zonal rotors from plasma of fat fed animals had a faster rate-zonal mobility than did the very low density lipoprotein isolated from plasma of control animals. The very low density lipoprotein isolated from plasma of fat fed rats contained fewer moles of phospholipids, cholesterol, and cholesteryl esters, relative to triglyceride than did the very low density lipoprotein from plasma of animals not receiving safflower oil. The molar ratio triglyceride:phospholipid:cholesterol:cholesterol esters in the very low denity lipoprotein was 100:42.0:22.1:44.5 in the control group and 100:35.4:17.8:19.5 in the fat fed animals. It is postulated that an important biochemical mechanism by which dietary triglyceride fatty acids consumed by the animal over a long period of time alter plasma concentrations of triglyceride, phospholipids, and cholesterol esters is the directive influence of plasma free fatty acid, derived from dietary triglyceride, on the secretion of very low density lipoprotein lipids by the liver.     

Ernährungsphysiologische Wirkung unterschiedlicher Gemische von Öle-, Linol- und Linolensäure bei wachsenden Schweinen 3. Wirkung auf die Nierenlipide

Physiological Effect of Various Mixtures of Oleic, Linoleic and Linolenic Acids on Growing Pigs: 3. Effect on Kidney Lipids From the feeding trial extensively described in the first report the kidneys of all animals are investigated with respect to content and composition of the lipids. The total lipids are independent on feeding fat and remain equal even at different relative organ weights. Distinct influences of the feeding fat are found in the fatty acid composition of the single lipid classes. The various phospholipids behave differently on the influence of exogenous fatty acids.     

Variation of triglycerides and fatty acid methyl esters in silkworm eggs during embryonic development

Neutral lipid composition of silkworm eggs showed remarkable differences with stages of embryonic development, such as one day after oviposition, diapausing, before incubation and before hatching. Large amounts of fatty acid methyl esters were found in lipids of eggs just before hatching, and fatty acid compositions in both triglycerides and fatty acid methyl esters varied with the lapse of time of the embryonic development. Polyunsaturated fatty acids were present in large amounts in fatty acid methyl ester fractions from eggs just before hatching and absent in those from diapausing and 1 day old eggs, while a large amount of polyunsaturated fatty acids was present in triglycerides in diapausing and 1 day old eggs and only small amounts were present in eggs just before hatching. The methyl esters were not formed as artifacts from free fatty acids and glycerides in silkworm lipids during the extraction procedure.     

Triglyceride composition ofmadhuca butyraceae seed fat

Fatty acid and triglyceride compositions of phulwara butter (Madhuca butyraceae seed fat) have been determined by combination of the techniques of systematic crystallization at low temperatures, pancreatic lipase hydrolysis, and gas liquid chromatography of methyl esters. The percentages of individual fatty acids were found to be palmitic, 55.6; stearic, 5.2; oleic, 35.9; and linoleic, 3.3. The special characteristic of the phulwara butter is its content of POP, 52.5%; PLP, 4.9%; POSt, 8.6%; POO, 14.4% and PPP, 7.7% (P, palmitic; St. stearic; O, oleic; and L, linoleic). 2-Monoglycerides obtained by lipolysis of this fat and its least soluble fraction contained 13,0% and 29.3% saturated acids, respectively. Phulwara butter may be a potential source of palmitic acid for the pharmaceutical industry.     

Diet-induced changes in the fatty acid composition of mouse hepatocyte plasma membranes

Hepatocyte plasma membranes were isolated from the livers of mice fed either a low fat diet or high fat diets containing polyunsaturated or saturated fat. The combined rate and isopycnic ultracentrifugation technique which was used produced highly purified hepatocyte plasma membrane fractions. The efficacy of the procedure was checked by electron microscopy and the assay of marker enzymes for the different subcellular organelles. Mice were maintained on a low fat diet until 60–70 days of age, when they were fed high fat diets containing polyunsaturated or saturated fat. The hepatocyte plasma membrane lipids of mice fed the polyunsaturated fat diet for 4 wk contained increased proportions of the major dietary unsaturated fatty acid, linoleic acid, and increased proportions of arachidonic acid. The proportion of linoleic and arachidonic acids decreased with continued feeding of the polyunsaturated fat diet. The hepatocyte plasma membrane lipids of mice fed the saturated fat diet contained increased proportions of oleic acid.     

Wirkung langkettiger Monoensäuren auf die Lipide in Nebennieren und Blutserum von Schweinen

Action of Long-Chain Monoenoic Acids on the Lipids of Adrenals and Blood Serum of Pigs The influence of soybean oil and rapeseed oil diets with varying fat content and erucic acid content on the lipids of adrenals and blood serum of pigs was studied. The content of total lipids, free sterols and sterol esters is influenced by the composition of the diet. The composition of the sterols is found to be the same in all lipid samples examined. The fatty acid composition of triglycerides of adrenals showed a characteristic dependence on the dietary fat, whereas no influence was observed in sterol esters, the typical transition lipids, due to large fluctuations between the individual animals. Moreover, independent of the type of feed, large differences were observed in the triglycerides and sterol esters of blood serum. Significant alterations by feeding rapeseed oil did not occur in adrenals and blood serum.