Regulation of fatty acid biosynthesis in Ehrlich cells by ascites tumor plasma lipoproteins

Fatty acid biosynthesis in Ehrlich cells in vitro was reduced when very low density lipoproteins (VLDL) isolated from the ascites tumor plasma were added to the incubation medium. The degree of inhibition was dependent on the VLDL concentration. At the VLDL concentrations usually present in the ascites plasma, there was a 30% decrease in biosynthesis as measured by³H₂O incorporation into fatty acids. Analysis of the labeled fatty acids by gas liquid chromatography indicated that this decrease was due to a reduction in fatty acid de novo biosynthesis and that chain elongation actually was increased when VLDL were present. Although ascites plasma low- and high density lipoproteins also produced a concentration-dependent inhibition of fatty acid biosynthesis, their effects were much smaller than those of the VLDL. Studies employing VLDL and radioactive free fatty acids indicated that the cells took up and utilized fatty acids derived from these lipoproteins. When VLDL were present, labeled free fatty acid incorporation into cell phospholipids, cholesteryl esters, and CO₂ decreased, whereas its incorporation into the cell free fatty acid pool increased. By contrast, the cells incorporated only very small amounts of fatty acid from either low- or high density lipoproteins. This suggests that the VLDL exert their inhibitory effect on fatty acid synthesis by supplying exogenous fatty acids to the cells. Presented in part at the AOCS Spring Meeting, Dallas, April 1975.     

Effects of the ratio of polyunsaturated and monounsaturated fatty acid to saturated fatty acid on rat plasma and liver lipid concentrations

The effects of dietary monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid+MUFA/saturated fatty acid (PUFA+MUFA/SFA) ratio on plasma and liver lipid concentrations were studied. In experiment I, when rats were fed with 40% fat (energy%, PUFA/SFA ratio 1.0) and 1% (w/w) cholesterol (C) diets for 21 d, a large amount of MUFA (28.1 energy%, PUFA+MUFA/SFA=5.7) in the diet was found to increase the plasma total C, triacylglycerol (TAG), and phospholipid (PL) as compared with the low-MUFA diet (7.0 energy%, PUFA+MUFA/SFA=1.4). The plasma very low density lipoprotein (VLDL)-C, VLDL-TAG, VLDL-PL, and low density lipoprotein (LDL)-C increased significantly in the high-MUFA diet group, but high density lipoprotein (HDL)-C did not change significantly. The high-MUFA diet resulted in greater accumulation of liver C but lesser accumulation of TAG. In experiment II, when dietary SFA was fixed at a certain level (13.2 energy%; PUFA+MUFA/SFA=2.0), rats given a larger amount of MUFA (23.1 energy%; PUFA/MUFA=0.2; MUFA/SFA=1.8) showed higher plasma and liver C levels than did the low-MUFA diet (7.7 energy%; PUFA/MUFA=2.5; MUFA/SFA=0.6). When PUFA was fixed at a certain level (24.4 energy%), there was not a significant difference in the plasma C level between the high-and low-MUFA dietary groups (PUFA+MUFA/SFA=4.8 and 8.4), but the higher PUFA+MUFA/SFA diet, which was high in MUFA/SFA ratio, significantly decreased the plasma HDL-C and TAG levels. However, when MUFA content was fixed at a certain level (16.4 energy%), no significant difference was observed between the two groups with different PUFA/SFA ratios of 0.2 and 4.1, but liver C level was raised in the higher PUFA/SFA diet. It appears that the PUFA/SFA ratio alone is unsuitable to predict the change of plasma C level, because a large amount of dietary MUFA may lead to an increase of plasma and liver lipids in rats. It seems that the prerequisites for keeping low plasma and liver C are (i) low MUFA/SFA ratio, (ii) high PUFA/MUFA ratio, and (iii) PUFA+MUFA/SFA ratio not to exceed 2.     

Essential and nonessential fatty acid oxidation in mice bearing Ehrlich ascites carcinoma

We tested the hypothesis that mobilized (essential) free fatty acids (FFA) are spared from oxidation in cancer-bearing animals. We injected tracers [1-¹⁴C]linoleate, [1-¹⁴C] palmitate and NaH¹⁴CO₃ intravenously as single rapid doses in separate groups of mice bearing Ehrlich ascites tumor (EAT) and controls, and measured breath¹⁴CO₂. The data from NaH¹⁴CO₃ injections were used to develop kinetic, compartmental models of the HCO ₃ ⁻ -CO₂ systems. These models were integrated with our earlier model of plasma FFA turnover for control and EAT-bearing mice. The integrated multicompartmental models were then fitted to breath¹⁴CO₂ data from mice injected with tracer FFA to compute the rates of FFA oxidation. FFA were not spared from an oxidative fate in our cancer-bearing vs normal animals; moreover, essential FFA were not preferentially spared from oxidation compared to nonessential FFA in the cancer-bearing mice.     

Effects of membrane fatty acid composition on sodium-independent phenylalanine transport in Ehrlich cells

We have examined Na⁺-independent phenylalanine transport in Ehrlich cells having different degrees of membrane fatty acid saturation. These differences were produced by growing the cells in mice fed a fat-free chow supplemented with either sunflower seed oil or coconut oil. Plasma membranes isolated from the cells grown on sunflower oil were enriched with polyenoic fatty acid, especially 18∶2, whereas those isolated from the cells grown on coconut oil were enriched in monoenoic fatty acids, primarily 16∶1 and 18∶1. Arrhenius plots of phenylalanine uptake showed two transitions. The temperatures of these transitions were different in the two cell preparations; 17 C and 24 C for the cells enriched in polyenoic fatty acids, 19 C and 28 C for those enriched in monoenoic fatty acids. Therefore, this transport system is sensitive to changes in the fatty acid composition of the lipid phase in which it operates. The activation energies, however, were the same in both cell preparations; 14, 8 and 4 kcal/mol. There also was no significant effect of the lipid modifications on either the K′_m or V′_max of this transport process. The K′_m for phenylalanine uptake from a choline medium remained constant as the temperature was raised from 17 C to 37 C, whereas the V′_max showed about a two-fold increase in both cell types. Phenylalanine exodus from the cells into an amino acid-free suspending medium, analyzed using first-order kinetics, also was not influenced by these membrane fatty acid modifications. The changes in the transition temperatures probably reflect differences in the degree of fatty acid unsaturation of lipids that surround and interact with the phenylalanine carrier. Such differences, however, do not appreciably influence the catalytic activity of this transport system.     

Chlorophyll-sensitized peroxidation of saturated fatty acid esters

Chlorophyll-sensitized peroxidation of methyl laurate and methyl stearate was carried out at 30–40 C under intermittent exposure to light from a 500 w tungsten bulb. Hydroperoxides were isolated by solvent partition, reduced to hydroxy esters and purified by silicic acid column chromatography and preparative thin layer chromatography (TLC). Gas liquid chromatography, TLC, IR spectrophotometry, NMR and mass spectroscopy of the hydroxy esters showed that the oxygen attack was exclusively on the α-methylenic carbon atom. One of 28 papers presented at the Symposium, “Metal-Catalyzed Lipid Oxidation,” ISF-AOCS World Congress, Chicago, September 1970.     

Spectral confirmation of trans monounsaturated C18 fatty acid positional isomers

The trans octadecenoic acid methyl ester isomers were obtained from a partially hydrogenated soybean oil sample and isolated by silver-ion high-performance liquid chromatography. The double bond configuration was confirmed to be trans by using gas chromatography-direct deposition-Fourier transform infrared spectroscopy. The double bond positions for nine individual trans octadecenoic acid positional isomers were confirmed by gas chromatography-electron ionization mass spectrometry after derivatization to 2-alkenyl-4,4-dimethyloxazoline. These nine trans positional isomers were resolved on either one of the two polar 100% cyanopropylpolysiloxane 100-m capillary columns, SP 2560 and Cp-Sil 88, at an isothermal temperature of 140°C. These nine isomers were confirmed to have double bonds at carbons C-8 through C-16. The pair of trans octadecenoic acid positional isomers with double bonds at C-13 and C-14 are reported for the first time to be resolved by gas chromatography. This work was presented in part at the 87th American Oil Chemists’ Society Annual Meeting in Indianapolis, IN, April 28–May 1, 1996.     

Direct conversion of lipid components to their fatty acid methyl esters

Summary Methyl esters were prepared from cholesteryl esters, phospholipids, and glycerides in substantially quantitative yields by methanolysis with large excess of sodium or potassium methoxide in absolute methanol. A silicic acid chromatographic adsorption column technique was described, which was effective in separating methyl esters from unsaponifiables such as sterols, pigments, etc., and free acids. Conditions for complete methanolysis of glyceride fats and oils requiring only 5 min. of reflux time were described. Quantitative conversion of fatty acids to methyl esters was accomplished by direct esterification with absolute methanol containing 4% HCL or H₂SO₄ and by methylation with diazomethane. Presented at the 50th Meeting, American Oil Chemists’ Society, New Orleans, La., April 20–22, 1959. Eastern Utilization Research and Development Division, Agricultural Research Service, U. S. Department of Agriculture.     

In vitro biosynthesis of prostaglandin E2 by kidney medulla of essential fatty acid deficient rats

Weanling rats were fed either a semi-synthetic diet with no fat, with 28% by wt partially hydrogenated fish oil, or with 28% by wt arachis oil (control diet) for 6 or 71/2 months. The in vitro conversion of arachidonic acid to prostaglandin E₂ by homogenates of the rat kidney medulla was measured by gaschromatography with electron capture detection. The kidney medulla of essential fatty acid deficient animals showed increased activity for the in vitro conversion of exogenous arachidonic acid to prostaglandin E₂ when compared to the controls. The change of the enzymatic activity in the essential fatty acid deficient animals was reversible, as shown by refeeding. Inhibition of the prostaglandin synthetase was found at exogenous substrate concentrations higher than 50–100 μM.     

饱和脂肪酸或酯与甲醛缩合反应热力学

利用Benson基团贡献法估算了饱和脂肪酸或酯与甲醛羟醛缩合反应生成多一个碳的α,β-不饱和脂肪酸或酯的标准生成焓、标准熵和摩尔比定压热容,对反应体系的热力学性质进行计算。分析了反应的方向与限度,考察了温度对反应热力学性质的影响,比较了热力学数据随产物分子结构的变化规律。结果表明:在498—698 K的温度区间内,文中涉及的生成通式为CH=2CR1COOH的反应,均为自发放热反应。当R1为H时,较烷烃取代基自发放热反应程度偏小,R1为烷烃取代基时,其碳链的增长对羟醛缩合反应热力学性质的影响可以忽略。生成通式为CH=2CHCOOR2的反应,反应热随R2取代基上与氧相连碳原子由—CH3,—CH2变化到—CH而降低,反应程度下降。     

Continual conversion of free fatty acid in rice bran oil to triacylglycerol by immobilized lipase

Rice bran oil containing 30–50% free fatty acid was continually converted to an oil containing more than 75% of triacylglycerol (TG) by means of immobilized lipase. The reaction was carried out at 60°C for 24 h with dehydration and reactant mixing by dry nitrogen flow under a positive nitrogen atmosphere. Enzymatic TG synthesis with evaporation by heating was not suitable because of the increasing peroxide value of the oil. Part of this article was presented at the annual meeting of the Japan Oil Chemists' Society at Sendai, Japan, October, 16, 1990.     

Biodegradation of estolides from monounsaturated fatty acids

Mono- and polyestolides, made from oleic acid, meadowfoam oil fatty acids and erucic acid, were subjected to biodegradation with mixed cultures of Penicillium verucosum, Mucor racemosus, and Enterobacter aerogenes. Fermentations were continued for 3, 5, 10, 15, 20, or 30 d. Meadowfoam oil and its fatty acids, oleic acid and soybean oil were also biodegraded under the same conditions. After 10 d, oleic acid and soybean oil were degraded 99.8 and 99.2%, respectively; meadowfoam oil and its fatty acids were degraded 89.0 and 97.7%, respectively. After 30 d, oleic acid-derived poly- and monoestolides were degraded 98.6 and 90.0%, respectively, meadowfoam estolides were degraded 75.7%, and erucic acid estolides were degraded 84.0%.     

In vitro conversion of erucic acid by microsomes and mitochondria from liver,kidneys and heart of rats

Microsomes and mitochondria of liver, kidneys, and heart were incubated with [14-¹⁴C]erucic acid in three assay media: one favorable for chain elongation (NADPH+KCN), another favorable for β-oxidation and the last one for shortening (NADP+KCN). Elongating reactions occurred mainly in microsomes, those of kidneys being very active; the mitochondria also showed some activity, heart mitochondria being, however, more active than the microsomes, when considering the amount of erucic acid activated. In the medium for β-oxidation, practically no shortened fatty acids were found. On the contrary, when β-oxidation was inhibited, and in the presence of NADP, the formation of shorter monoenes, probably in the outer membrane of the mitochondria, was observed, namely eicosenoic acid in high amount, oleic acid and hexadecenoic acid. Mitochondria from liver were very active as were those of heart, when compared with the quantity of activated erucic acid. In heart, the mitochondria shortened erucic acid into oleic acid and hexadecenoic acid, which were then probably used as energy substrates. With carnitine and without NADP, shortened fatty acids were formed in the mitochondria of liver, probably by the first reactions of β-oxidation. In this case, the proportions of oleic acid and hexadecenoic acid were higher than with NADP alone. In the presence of carnitine and NADP, the level of the chain-shortening reaction did not differ from that observed with NADP alone. It appears, therefore, that the activated erucic acid is mainly directed towards shortening reactions and not towards transfer reactions across the mitochondrial membranes.     

Crystallization of glycine in water/saturated fatty acid emulsions

It was found that carbon chain length of fatty acids strongly affects polymorphic selection in the cooling crystallization of glycine from water/saturated fatty acid emulsions. Two-dimensional packing density of saturated fatty acid head groups, which is inversely proportional to the number of carbon atoms, was shown to be responsible for polymorphic selection of glycine: γ-glycine was obtained from the emulsions of hexanoic acid and octanoic acid, whereas α-glycine was found to crystallize from the emulsions of dodecanoic acid, tetradecanoic acid, hexadecanoic acid and octadecanoic acid. Those results indicate that molecular structure of γ-glycine is only well matched with molecular structure of head groups of hexanoic acid and octanoic acid at the interface of the emulsion, and thus such molecular interface provides the preferential site for the organization of γ-form crystal structure from the liquid-like cluster of glycine.     

Estimating the average carbon chain length of saturated fatty acid esters by infrared spectroscopy

The average carbon chain length of saturated fatty acid esters can be determined by comparing absorption intensities in the 3.3 and 5.75 μ infrared regions. Data are presented for triglycerides, monoglycerides, and methyl esters. The method was used to follow the fractionation of hydrogenated milk fat from acetone, and the average values for fatty acid chain length were in good agreement with those obtained by gas chromatographic methyl ester analysis. The I.R. method is particularly applicable when only a few mg of sample is available and the material being fractionated contains both long and short chain saturated fatty acids. Authorized for publication August 9, 1961, as Paper No. 2590 in the Journal Series of the Pennsylvania Agricultural Experiment Station. Supported in part by the U. S. Public Health Service (H3632).     

Metabolic aspects of positional monounsaturated fatty acids isomers

Absorption and distribution of positionalcis andtrans octadecenoic acid isomers in lipids from rat, egg and human tissues are reviewed. Selected data on enzyme, single-cell, and whole-animal studies with positional octadecenoic acid isomers are summarized and compared.     

Hydrogenation of monounsaturated and ethylene- and methylene-interrupted diunsaturated fatty acid esters on nonmetallic palladium-on-resin II

Methycis-9-octadecenoate (methyl oleate;c9), methylcis-9,cis-13-octadecadienoate (c9,c13) and a 50∶50 mixture of this diene with methylcis-9,cis-12-octadecadienoate (methyl linoleate;c9,c12) have been hydrogenated on a nonmetallic palladium-onresin catalyst in acetone as a solvent at 40 C and atmospheric hydrogen pressure. The monoene is hydrogenated very slowly, butc9,c12 is reduced easily and quickly. The ethylene-interrupted diene reacts more slowly thanc9,c12, but considerably faster thanc9, because active methylene-interrupted dienes are intermediates by double-bond migration. This isomerization process also results in the formation of inactive polymethylene-interrupted dienes, which accumulate during hydrogenation. Alsoc9 isomerizes considerably during reduction. In the 50∶50 mixture,c9,c12 is hydrogenated about eight times faster thanc9,c13. The activity of the catalyst for thec9,c12 hydrogenation described previously (1) is considerably higher than that derived from the present data. The experiments described in this study were carried out about eight months later, so that we have to deal with an older catalyst. However, reproduction of the catalyst resulted in the same activity. Furthermore, we used a new batch ofc9,c12 for these experiments, which was purified in the same way as the previous one. The catalyst is probably sensitive to apolar compounds which may be present inc9,c12 and which are not removed by alumina. Small amounts of these compounds may have a drastic influence on the activity of the catalysts under investigation because the catalyst dosing is very low. We emphasize that, though the activity may vary to some extent (depending on substrate quality), the selectivity and the isomerization pattern do not change.     

Reactions of fatty acid chlorides: II. Synthesis of monohydrazides or dihydrazides by acylation of hydrazine hydrate with saturated fatty acid chlorides

The acylation of hydrazine hydrate with a series of saturated fatty acid chlorides containing from eight to 18 carbon atoms was studied under a variety of conditions in order to obtain the desirable fatty acid monohydrazides. Optimum yields were obtained (ranging from 31.5% to 75% as the series ascended from C-8 to C-18) for the even-numbered monohydrazide members through the use of a large excess of hydrazine hydrate in several organic solvents. Diethyl ether was found to be suitable if the acid chloride is dissolved in it and added slowly to a cold mixture of hydrazine hydrate in ether. The Schotten-Baumann technique was found suitable for the preparation of the symmetrically substituted fatty acid dihydrazides in better than 82% yields when one mole of hydrazine hydrate was acylated with two of acid chlorides. Physical and chemical properties of both series of fatty nitrogen derivatives are briefly treated. Stearic monohydrazide was condensed with acetonylacetone to give a substituted pyrrole. An unsymmetrical dihydrazide was prepared by the acylation of myristic monohydrazide with lauroyl chloride. Stearic dimethylhydrazide was prepared by the acylation of dimethylhydrazine with stearoyl chloride. Two quaternizations of this product were carried out. Part I. JAOCS31, 151 ({dy1954}). Presented at the AOCS Meeting, New York, October 1960.     

Separation of saturated,unsaturated, and acetylenic fatty acid isomers by silver resin chromatography

A column packed with silver-saturated ion exchange resin (Amberlyst XN 1010) was found to have lipid separation capabilities superior to Amberlyst XN 1005 and similar to Amberlite XE 284. The separation of unsaturated fatty methyl ester isomers by silver resin chromatography using methanol as the eluting solvent has been extended to mixtures containing polyunsaturate and acetylenic fatty esters. Separations are possible on the basis of both total number of double bonds and the geometric configuration. Mixtures containing saturates, elaidate, oleate, linoleate, and linolenate can be separated, but 10% 1-hexene must be added to the methanol to elute the linolenate. Mixtures containingtrans,trans-;trans,cis-; andcis,cis-octadecadienoate isomers have also been separated, and partial resolution ofcis-9,cis-12- andcis-2,cis-15-octadecadienoate isomers was obtained. Sterolate, a monounsaturated acetylenic fatty ester was eluted at the same time as oleate. Crepenynate (cis-9-octadecen-12-ynoate) can be separated from linoleate but not fromcis,trans-octadecadienoate. Employed at the Northern Regional Research Center under a USDA cooperative education program with Purdue University.