Tumor lipids: Carbon number distribution of triglycerides and glyceryl ether diesters

Triglycerides and glyceryl ether diesters were isolated from a number of transplantable rat and mouse tumors and analyzed intact by gas liquid chromatography (GLC). The carbon number distributions of the triglycerides were distinctly different from those of the glyceryl ether diesters. Both glyceride classes contained abnormally high molecular weight species. The data support earlier evidence that indicated diglycerides used for the biosynthesis of phosphatides are also precursors of triglycerides in neoplasms. Glycerides isolated from three centrifuged fractions of Ehrlich ascites cells exhibited similar carbon number distributions. The results indicate a random distribution of triglyceride and glyceryl ether diester molecular species among cellular organeiles. Triglycerides, glyceryl ether diesters and neutral plasmalogens of the same carbon number were partially resolved by GLC. Under contract with the U.S. Atomic Energy Commission.     

Dihydromatricariate-based triglycerides,glyceride ethers,and waxes in the australian soldier beetle,Chauliognathus lugubris (Coleoptera: Cantharidae)

The soldier beetleChauliognathus lugubris is shown to contain triglycerides and glyceride ethers of 8-dihydromatricaria acid, and waxes of the C₁₂ homolog, of this acid, as well as the previously reported free acid. The triglycerides contain one, two, or three dihydromatricariate moieties, with any remaining positions esterified with normal fatty acids. The glyceride ethers were monostearyl ethers of glycerol esterified with dihydromatricaria acid and oleic or linoleic acid. The waxes, which also include a dihydromatricaria chromophore in the alcohol moiety, occur only in the females and are present in paired accessory glands in the abdomen. The ethers are restricted to females and appear to be associated with developing eggs. The triglycerides are much more abundant in females than males. Triglycerides, glyceride ethers, and waxes represent about 95% of the dihydromatricariate moiety (average, ca. 590 g) in females with free acid the remainder; in males free acid is present to over 50% (ca. 22 g) and the remainder is triglyceride (ca. 15 g). Larvae contain mainly tridihydromatricariate-substituted triglyceride and a smaller quantity of the free acid.     

合成系列高纯度单脂肪酸甘油酯

用丙酮保护的一锅合成法,即通过甘油与丙酮反应制得异亚丙基甘油,在对甲苯磺酸催化作用下与脂肪酸反应制备了单月桂酸甘油酯、单肉豆蔻酸甘油酯、单棕榈酸甘油酯、单硬脂酸甘油酯、单山嵛酸甘油酯5种单脂肪酸甘油酯。制备的系列单脂肪酸甘油酯的质量分数均大于90%,收率都高于75%。并根据熔点测定和红外图谱分析结果,确定了产物结构。实验发现系列单甘酯合成中脂肪酸碳数与反应难易间的规律为:脂肪酸碳数越多,反应越难于进行,单甘酯的质量分数和收率也越低,这一规律与热力学计算所得规律一致。     

Fatty acid specificity of glyceride synthesis by homogenates of bovine mammary tissue

Fatty acid esterification by cell free preparations of bovine mammary tissue was investigated to determine if the type of long chain fatty acid supplied might influence the rate of triglyceride synthesis by that tissue. Homogenates of lactating bovine mammary tissue esterified¹⁴C-fatty acids into glycerides at rates dependent upon chain length and degree of unsaturation. Palmitic, stearic, oleic and linoleic acids were esterified at rates consistent with their concentration in milk fat. A comparison of free fatty acid concentrations of mammary tissue with levels saturating esterification suggested that supply of fatty acids does not limit glyceride synthesis. Certain combinations of fatty acids were facilitory, competitive or inhibitory to esterification. Stearic acid complimented esterification of palmitic and oleic acids. Unlabeledtrans-11-octadecenoic acid did not compete with¹⁴C-palmitate as efficiently in the esterification process as did unlabeledcis-9-octadecenoic acid, indicating that the mammary gland may preferentially esterify thecis-isomer of C-18∶1. Linoleic acid inhibited esterification of palmitic, stearic and oleic acids. Michigan Agricultural Experiment Station Journal Article No. 5100.     

Isolation and characterization of glycerides in human hair lipids by thin-layer and gas chromatography

Techniques for the quantitative analysis of hair lipids using thin-layer chromatography (TLC) together with a proximate analysis of components in one sample deduced by these criteria are presented. Mono-, di- and triglycerides were separated by TLC using Silica Gel G as adsorbent. The chromatoplates were developed with 98% acetone+2% petroleum ether. Glycerides moved with the solvent front. The requisite portions were scraped off the plates and extracted with acetone and ether. Further TLC, limiting the migration of triglycerides and diglycerides was afforded by use of 95% ethanol as solvent in one direction while monoglycerides moved with the solvent front. For the separation of monoglycerides, chloroform was used as solvent in a second direction. Reference standards and several mixtures were run simultaneously and the spots identified by charring with concentrated sulfuric acid containing dichromate. Additional checking was effected by IR spectra. For determination of glyceride composition, methyl esters of the component fatty acids were prepared by transesterification and submitted to gas chromatography. Comparison of the levels of each of the constituent fatty acids showed no remarkable differences between the three classes of glycerides in one hair lipid pool. Although certain discrepancies in the amounts of a few fatty acid components might be construed for one pool of lipids from hair of white full-headed men (WF-9A) in contrast to findings with two Negro pools, no unequivocal conclusions can be drawn presently.     

Positional specificity of adipose tissue lipoprotein lipase

The positional specificity of preparations of lipoprotein lipase derived from rat epididymal adipose tissue was investigated. The enzyme preparations were a crude extract of acetone powder of the whole tissue, partially purified lipoprotein lipase fractions a and b separated by gel chromatography from such an extract, and lipoprotein lipase activity eluted from adipose tissue into a medium by incubation with heparin in vitro. The enzyme preparations were incubated with triglyceride substrate labeled with³H in the glycerol moiety and with¹⁴C in the fatty acid esterified to the 2 position of the glycerol. The reaction products were separated by thin layer chromatography. All preparations preferentially hydrolyzed the 1(3) ester bonds of the tri- and diglycerides, indicating that, like lipoprotein lipase from other sources, the adipose tissue enzyme has a specificity for the 1(3) position.     

The purification and specificity of a lipase fromVernonia anthelmintica seed

Acetone powders prepared fromVernonia anthelmintica seed catalyzed the release of 6.4 to 9.6 μ-moles of free fatty acids per milligram of protein when blended with olive oil and phosphate buffer and shaken for 20 min at 43 C. A 20 fold purification was achieved by differential centrifugation of an ammonium hydroxide extract of the acetone powder. Results from Sephadex G-200 chromatography and polyacrylamide gel electrophoresis suggested that the lipase activity was associated with a molecule of molecular weight greater than 200,000. Free fatty acids, 1,2- and 1,3-diglycerides, monoglycerides and glycerol were found in the digestion products. With most substrates the 1,2-to 1,3-diglyceride ratio was approximately 2∶1 and monoglycerides tended to accumulate. Analysis of the digestion products from synthetic triglycerides of known structure indicated that both primary and secondary ester positions of the triglyceride molecule were hydrolyzed and that considerable isomerization of 1,2-diglyceride to 1,3-diglyceride occurred. The monoglyceride was consistently lower than the 1,2-diglyceride and in the majority of cases also lower than the 1,3-diglyceride in the fatty acid originally present in the 2 position of the triglyceride. No fatty acid preference was observed. Scientific contribution No. 316. Presented in part at the AOCS Meeting, Philadelphia, October 1966.     

Herstellung und DC-Trennung von Teilestern „techn. Monoglyceride”︁ mit Carbonsäuren

Preparation and TLC-Separation of Partial Esters of “Technical Monoglycerides” with Carboxylic Acids Technical monostearate (DAB 7) and distilled monostearate were partially esterified with formic acid, acetic acid, propionic acid, butyric acid, valeric acid, capronic acid, lactic acid, tartaric acid, diacetyl tartaric acid, oxalic acid, malonic acid, succinic acid and citric acid. Introduction of the carboxylic acids accompanied by interesterifications leads to considerable changes in melting point, consistency and other analytical characteristics. A series of the partial esters of carboxylic acids is separated by TLC into unesterified starting glycerides, partially esterified and completely esterified monoglycerides, esterified diglycerides and partly into their positional isomers. The similarity between a series of chromatograms is probably due to the large molecules of the glycerides, whereas the nature of short chain carboxylic acid introduced does not affect the TLC behaviour significantly. TLC provides an insight into the complex character of partial esterification of “technical monoglycerides” with carboxylic acids.     

Transport of diacylalkylglycerols in chylomicrons and very low density lipoproteins of rat intestinal lymph following intragastric administration of 1,3-dioctadecenoyl-2-hexadecylglycerol

The triacylglycerol (TG) analog 1,3-dioctadecenoyl-2-hexadecyl glycerol was used in the study of the transport of dietary lipids by lipoprotein fractions of rat intestinal lymph. 1,3-Diacyl-2-alkyl glycerols (DAG) are hydrolyzed by pancreatic lipase to form 2-alkyl glycerols and free fatty acids. These hydrolysis products are then absorbed, and DAG are resynthesized within the intestinal mucosa. Intestinal lymph of rats was collected following intragastric administration of 1,3-dioctadecenoyl-2-hexadecyl glycerol. The DAG to TG ratios in very low density lipoprotein (VLDL) and chylomicron fractions were determined as a measure of the incorporation of lipid of dietary origin. The ratio of DAG to TG in the VLDL-2 (S_f 12–100) fraction ranged from0.06 to 0.56 indicating a significant amount of DAG transported relative to TG. The glyceryl ether to TG ratio increased with mean lipoprotein volume from the VLDL-2 fraction to the chylomicron (S_f>400) fraction. The correlation between glyceryl ether to TG ratio and average volume and between the amount of DAG per ml of original lymph and average volume within the chylomicron fraction was 0.99. Thus, the amount of dietary fat transported was correlated with the size of the chylomicrons produced. The glyceryl ether to TG ratio was positively correlated with the average volume of the lipoprotein fractions isolated (chylomicrons, chylomicron rich (S_f>100), VLDL-1 (S_f 100–400) and VLDL-2) (r=0.87). These results suggest that the size of the lipoproteins produced by the intestine is determined by the amount of fat available for transport and that particles of larger diameter are formed by the addition of lipid of dietary origin to existing VLDL. Scientific contribution no. 702, Agricultural Experiment Station, University of Connecticut, Storrs, Connecticut 06268     

Uptake of blood triglyceride by various tissues

Triglycerides are transported in the blood in chylomicrons and very low density lipoproteins. Electron microscopic studies indicate that these particles, which range in diameter from 0.03–0.6 μ, cannot cross the capillary endothelium in most tissues. There is now considerable evidence that the triglycerides are hydrolyzed to free fatty acids (FFA) during uptake and that this process is catalyzed by lipoprotein lipase. The enzyme is found in nearly all tissues that utilize circulating triglyceride, and the level of activity, in individual tissues, varies with nutritional and physiological states that affect triglyceride uptake, such as fasting, diabetes and pregnancy. Studies in perfused adipose tissue with doubly labeled chylomicrons showed that hydrolysis occurs outside of the blood stream. Two-thirds of the fatty acids are incorporated into tissue triglyceride and the rest are release as FFA, with glycerol, to the blood. Infusion of heparin causes immediate release of lipoprotein lipase activity to the blood and decreases the amount of chylomicron-triglyceride hydrolyzed by the tissue. Electron microscopic cytochemical studies showed that hydrolysis of blood glycerides by lipoprotein lipase in adipose tissue occurs within the capillary endothelial cells and in the subendothelial space near the pericytes, but not in the capillary lumen or near the fat cells. The results indicate that the fatty acids of chylomicrons cross the capillary endothelium as glycerides and FFA, within a membrane-bounded system, and cross the extravascular space to the fat cells as FFA. Presented at the AOCS Meeting, Atlantic City, October 1971.     

Long chain fatty alcohols in normal and neoplastic tissues

Small quantities of long chain fatty alcohols (esterified or free or both) were found in four normal tissues (about 0.01% of total neutral lipids) and three neoplasms (about 0.3% of total neutral lipids). The major chain lengths (16∶0, 18∶0 and 18∶1) of the fatty alcohols in both normal and neoplastic cells qualitatively resemble the O-alkyl chain lengths of glyceryl ethers. Our data showing that long chain fatty alcohols occur in vivo support the biological significance of the metabolic pathway that uses fatty alcohols as a substrate for the alkyl chain in glyceryl ether biosynthesis.     

The triglyceride composition of linseed oil

The triglyceride composition of linseed oils obtained under different ecological conditions and having different fatty acid compositions was determined by a combination of several chromatographic techniques. The triglyceride mixture was first separated in 8 fractions of different polarity by reversed-phase paper chromatography. Each glyceride fraction was then separated in a partition chromatographic system as the triglyceride coordination complexes with silver ions into individual compounds. The fatty acid compositions of the original oil, single glyceride fractions, and individual triglycerides were determined by gas-liquid chromatography. The molar ratio between the two neighboring glyceride fractions was determined by relating the fatty acid composition of each fraction to the fatty acid composition of their sum. The triglyceride composition of the total oil was then calculated from these results. The presence of 18–19 triglycerides was ascertained in the samples studied, and the molar concentration of each glyceride was estimated. Linseed oil contains only triunsaturated and monosaturated-diunsaturated triglycerides. Within each of these types the fatty acid distribution is close to random. At the same time, the content of some triglycerides departed regularly from a random pattern. A method for calculation of linseed oil triglyceride composition from the fatty acid composition is given. The same general pattern of glyceride formation in linseed is followed regardless of ecological conditions; therefore, the qualitative and quantitative triglyceride composition reflects the differences in fatty acid composition of linseed oil.     

Glycerol Esters from Real Waste Cooking Oil Using a Robust Solid Acid Catalyst

Notwithstanding the food-for-fuel debate, turning waste cooking oil and fat (WCO) into a valuable product is a classic example of green chemistry. We demonstrate that sulfated zirconia and lanthanum-supported sulfated zirconia are good catalysts for the esterification of WCO free fatty acids (FFAs) with glycerol, giving high-value monoglycerides. Various catalysts were first screened using palmitic acid as a model FFA. Subsequently, six 10-kg batches of actual WCO were collected from commercial cookeries over a period of 28 weeks, pre-treated in a purpose-built decanter and esterified with industrial grade glycerol using heterogeneous catalysis. Good yield and turnovers were obtained. The pre-treatment stage and the catalytic esterification experiments are described and discussed.     

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.     

Separation of eicosapentaenoic acid and docosahexaenoic acid in fish oil by kinetic resolution using lipase

The objective of this study was to investigate the use of lipases as catalysts for separating eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in fish oil by kinetic resolution. Transesterification of various fish oil triglycerides with a stoichiometric amount of ethanol by immobilized Rhizomucor miehei lipase under anhydrous solvent-free conditions resulted in a good separation. When free fatty acids from the various fish oils were directly esterified with ethanol under similar conditions, greatly improved results were obtained. By this modification, complications related to regioselectivity of the lipase and nonhomogeneous distribution of EPA and DHA into the various positions of the triglycerides were avoided. As an example, when tuna oil comprising 6% EPA and 23% DHA was transesterified with ethanol, 65% conversion into ethyl esters was obtained after 24 h. The residual glyceride mixture contained 49% DHA and 6% EPA (8:1), with 90% DHA recovery into the glyceride mixture and 60% EPA recovery into the ethyl ester product. When the corresponding tuna oil free fatty acids were directly esterified with ethanol, 68% conversion was obtained after only 8h. The residual free fatty acids comprised 74% DHA and only 3% EPA (25:1). The recovery of both DHA into the residual free fatty acid fraction and EPA into the ethyl ester product remained very high, 83 and 87%, respectively.     

Glycerol Esters from Real Waste Cooking Oil Using a Robust Solid Acid Catalyst

Notwithstanding the food-for-fuel debate, turning waste cooking oil and fat (WCO) into a valuable product is a classic example of green chemistry. We demonstrate that sulfated zirconia and lanthanum-supported sulfated zirconia are good catalysts for the esterification of WCO free fatty acids (FFAs) with glycerol, giving high-value monoglycerides. Various catalysts were first screened using palmitic acid as a model FFA. Subsequently, six 10-kg batches of actual WCO were collected from commercial cookeries over a period of 28 weeks, pre-treated in a purpose-built decanter and esterified with industrial grade glycerol using heterogeneous catalysis. Good yield and turnovers were obtained. The pre-treatment stage and the catalytic esterification experiments are described and discussed.

     

耐低温SBS热熔压敏胶的研制与应用

以长链高级脂肪酸(H18)、松香和甘油为原料,合成了低软化点、低酸值、低黏度和高透明性的H18改性松香甘油酯;然后以此作为SBS(苯乙烯-丁二烯-苯乙烯热塑性弹性体)基热熔压敏胶(HMPSA)的增黏树脂,探讨了H18改性松香甘油酯含量对HMPSA性能的影响。结果表明:当w(H18改性松香甘油酯)=10%时,HMPSA的环形初粘力、180°剥离强度相对最大,比未改性体系分别增加了54.81%、35.29%;适量的H18改性松香甘油酯可有效降低HMPSA的玻璃化转变温度(T_g)、提高HMPSA的耐寒性。     

The pancreatic hydrolysis of natural fats. IV. Some exotic seed fats

Eight exotic seed fats (karanja, kusum, neem and aceituno oils, malabar tallow, kokum butter and mowrah and dika fats) have been subjected to pancreatic hydrolysis. From the original fatty acid compositions, and those of the monoglycerides produced by hydrolysis, the fatty acid distributions have been determined, and their probable glyceride compositions calculated. The significance of the observed fatty acid distributions is discussed; and an expression relating the glyceride composition to the overall fatty acid composition is shown to give satisfactory agreement with the calculated values, for these, and other vegetable fats.     

Preparation of Medium Chain Triglycerides with the Use of Physical Refining

The application of medium chain triglycerides (MCTs) of fatty acids, mainly with C₈ and C₁₀ carbon atoms, has extended in recent years from their original clinical use for patients with deficient lipid metabolism to their utilization in infant and parenteral feedings. They may be useful in treating obesity and various other ailments. The medium chain fatty acids are prepared by fractional distillation of coconut and palmkernel oil fatty acids and the industrial synthesis of MCTs is much more complicated than the preparation of common edible oils. The esterification of medium chain fatty acids with glycerol must lead to an almost complete elimination of monoglycerides because of their bitter taste. The free fatty acid content of the end product has to be very low and the deodorization step creates problems owing to the hydrolysing action of the steam. The necessity of using a large excess of fatty acids in the esterification step to eliminate the monoglycerides, results in considerable refining losses, which increase the cost of MCTs manufacture. The present investigation was carried out with the object of replacing the alkali treatment of the esterified product by physical refining, i.e. by the removal of free fatty acids by distillation. This was achived by dispensing with the use of a catalyst during the esterification and by using nitrogen or preferably carbon dioxide instead of steam during the deacidification-deodorization step. This permitted a substantial increase in the temperature of the precess and the formation of a satisfactory product in a reasonable working time.     

Abnormal lipid composition of fat tissue in human mesenteric panniculitis

Mesenteric fat tissue obtained at autopsy from 6 patients with mesenteric panniculitis (MP) were found to contain significant amounts of cholesteryl esters (CE). In addition, samples from 3 of these cases were found to contain 0.5–1.3% free cholesterol, 0.9–1.9% free fatty acids (FFA), 0.6–2.5% 1-alkyl glyceryl ether diesters and small amounts of squalene. Two of these tissues also contained alk-1-enyl glyceryl ether diesters. The fatty acid compositions of the CE, FFA, triacylglycerides and glyceryl ether diesters (GEDE) were determined and oleic acid (18∶1) was found to be the major fatty acid. The alkyl group composition of the GEDE consisted essentially of 16∶0 and 18∶0 and 18∶1 carbon atoms in both types of ethers.