Fat metabolism in higher plants: Metabolism of medium chain fatty acids

Cell free preparations of avocado mesocarp and spinach leaf tissue rapidly convert lauryl CoA to DL-3-hydroxyl lauric acid as well as 2-, and 3-dodecanoic acids. The conversion does not occur under anaerobic conditions unless a suitable redox carrier such as ferredoxin is present. H2 18O is incorporated into the 3-hydroxyl function, but O2(18) is not. The characteristics of this system are presented and a possible function of this system is proposed.     

Bioactivity and emerging role of short and medium chain fatty acids

Cardiovascular disease (CVD) and insulin resistance are directly linked to overweight and obesity. Thus, any dietary strategy capable of causing weight reduction will lower CVD and diabetes risk. Oils rich in medium‐chain saturated fatty acids (MCFA) are among several dietary components that may have potential in the treatment of obesity. MCFA are less energy dense and highly ketogenic compared to long‐chain saturated and unsaturated fatty acids (LCFA). MCFA also differ from LCFA in their digestive and metabolic pathways, since they are easily oxidized and utilized as energy, with little tendency to deposit as body fat. The dietary intake of short (SCFA) and medium‐chain saturated fatty acids from natural food sources is approximately 2.4 g/day and accounts for about 9% of the total saturated fatty acid (SFA) intake. Although early clinical studies with high levels of MCFA resulted in increased levels of plasma triacylglycerols (TAG) and low‐density lipoprotein cholesterol (LDL‐C), and reduced levels of high‐density lipoprotein cholesterol (HDL‐C) compared to diets enriched in unsaturated LCFA, these adverse effects have not been observed in more recent studies with smaller more realistic amounts of MCFA. The lower caloric value of SCFA and MCFA and their unique metabolic features form the basis for their clinical use in enteral and parenteral nutrition and for novel reduced calorie lipids for use in conventional food products.     

Preparation and properties of some polyglycerol esters of short and medium chain length fatty acids

Mono- and diesters of the short and medium chain acids were prepared with polyglycerols and compared with their corresponding mono- and diglycerides. The physical and chemical properties of such partial esters of polyglycerols, particularly with respect to their oil, water and solvent solubility are given. Polyglycerol esters become more hydrophilic as the molecular weight of the polyol increases. Polyglycerol esters become less hydrophilic as the length of the aliphatic chain of the acid used in esterification is increased. Polyglycerol esters of such short and medium chain fatty acids show promise in applications where surface activity and emulsification, solubilization of oil and water systems is desired. Presented at the AOCS Meeting, New York, October 1968.     

Sulfonated branched chain fatty acids and esters

In continuation of work reported a year ago describing branched chain fatty acids, a series of monosodium methyl 2-sulfo-2-alkylalkanoates [RR'C (SO₃Na) CO₂CH₃] were synthesized. The surface active properties of these compounds were evaluated and compared with the corresponding disodium 2-sulfo-2-alkylalkanoates [RR'C (SO₃Na)CO₂Na]. Alkaline hydrolysis rates show that the sodium methyl esters are stable. Relative to the disodium salts, these compounds exhibit better wetting properties and more stable foams. Presented at the AOCS Meeting, Cincinnati, October 1965. E. Utiliz. Res. Dev. Div., ARS, USDA.     

Branched chain fatty acids and sulfonated derivatives

Several 2-alkyl fatty acids containing 18–21 carbon atoms, were synthesized by tertiary butyl peroxide catalyzed addition of linear aliphatic carboxylic acids to normal terminal olefins. The products obtained in 35–70% yields were purified by fractional distillation. The acids were sulfonated with sulfur trioxide dioxane adduct and isolated as the disodium salts in 60–80% yields.

$$ \begin{gathered} R - CH_2 CO_2 H + R'CH = CH_2 \xrightarrow[{125 - 160C}]{{Perioxide}}R'CH_2 CH_2 - CH(R)CO_2 H \hfill \\ R' - CH_2 CH_2 CH(R)CO_2 H + SO_3 \xrightarrow{{CCl_4 }}R'CH_2 CH_2 C(SO_3 H)(R)CO_2 H \hfill \\ \end{gathered} $$     

Extracting long-chain fatty acids from a fermentation medium

Several solvents were evaluated for extracting free long-chain FA (LCFA) from a fermentation medium. Chloroform, chloroform/methanol (1∶1), hexane, and hexane/methyl tert-butyl ether (MTBE) (1∶1) were evaluated as alternative extraction solvents. Parameters considered for optimizing LCFA recoveries included pH and ionic strength. Maximal LCFA recoveries were obtained by adding 2 mL of the hexane/MTBE (1∶1) solvent mixture, 80 μL of 50% H₂SO₄, and 0.05 g NaCl to 1 mL of the aqueous sample and mixing for 15 min at 200 rpm. This method quantified saturated LCFA [capric acid (C_10∶0) to stearic acid (C_18∶0)] and unsaturated LCFA with 18 carbons [linoleic acid (C_18∶2) and oleic acid (C_18∶1)] with a 98 to 100% recovery. Caproic (C_6∶0) and caprylic (C_8∶0) acids were characterized by 27 and 76% recoveries, respectively.     

代谢工程改造酵母生产多不饱和脂肪酸的研究进展

多不饱和脂肪酸因其在食品和医药领域的广泛作用而得到人们极大的关注,当前利用微生物发酵生产多 不饱和脂肪酸具有诸多优点,由于酵母生产迅速且生物量较高,利用酵母生产多不饱和脂肪酸已成为人们关注 的热点。本文综述了代谢工程改造酵母生产多不饱和脂肪酸的研究进展,以常规酵母-酿酒酵母和非常规酵母- 解脂耶氏酵母为例,介绍了酵母菌中多不饱和脂肪酸的代谢途径、酵母产油脂的生化机制、代谢工程改造酵母 产多不饱和脂肪酸以及不饱和脂肪酸积累对酵母耐受性的影响。以后研究工作的重点是进一步加强对酵母生产 多不饱和脂肪酸的机理研究,并以此为来指导代谢工程改造酵母生产多不饱和脂肪酸。     

Derivatives of long chain fatty acids as lubricant components

Soaps ofcis-9,10-epiminostearic acid have been synthesized and tested as components of lubricating greases. The lithium, sodium and potassium soaps were obtained by the reaction ofβ-iodocarbamates with the proper alkali metal hydroxides in the ring closure step of the iodine isocyanate (INCO) procedure for the synthesis of internal aziridines. The soaps of other metals, namely barium, lead, aluminum and indium, were prepared from the alkali metal epiminostearates by metathetical reactions. As a result of this method of preparation, the aluminum and the indium soaps were isolated as the dicarboxylates rather than as the tricarboxylates. For the purpose of comparison a sample of lithium 9,10-epiminostearate was also prepared from theβ-chlorocarbamate obtained by the addition of dichlorourethane (DCU) to methyl oleate. Since DCU addition is nonstereospecific, the soap obtained in this preparation was a mixture ofcis- andtrans-aziridines. Evaluation of the metal soaps as grease thickeners was made. The lithium derivative showed considerable promise as thickener having additional desirable properties. Presented at the AOCS-ISF World Congress, Chicago, September 1970. E. Market. Nutr. Res. Div. ARS, USDA.     

Production of odd chain polyunsaturated fatty acids byMortierella fungi

A soil isolate,Mortierella alpina 1S-4, was found to show high production of odd chain polyunsaturated fatty acids (PUFAs) among various arachidonic acid-producingMortierella strains tested. The fungus mainly accumulated 5,8,11,M-cis-nonadecatetraenoic acid. With 5%n-hepta-decane and 1% yeast extract as growth substrates, the amount of C_19:4:4 acid accumulated reached 44.4 mg/g dry mycelia (0.68 mg/mL of culture broth). This value accounted for 11.2% of the total fatty acids in the extracted lipids from mycelia, and odd chain fatty acids comprised over 95% of the total mycelial fatty acids. The addition of sesamin, a specific inhibitor of A5 desaturation, caused an increase in C_19:3 acid and an accompanying decrease in C_19:4 acid. On the other hand, species ofMortierella that could not produce C-20 PUFAs accumulated C-17 acids, but no C-19 PUFAs, when grown with fatty substrates with an odd chain skeleton. The odd chain PUFAs were distributed in both neutral and polar lipids. The biosynthetic route to C_19:4 acid was presumed to mimic the n-6 route to arachidonic acid as follows: C_17:0 → C_17:1→ C_17:2→ C_17:3 → C_19:3 → C_19:4 acids. On leave from Suntory Ltd.     

Binding of long chain fatty acids to β-lactoglobulin

β-lactoglobulin (BLG), a bovine milk protein that is available commercially in crystalline form, binds long chain free fatty acids (FFA). The binding data were analyzed with a model containing one primary FFA binding site and a large number of weak secondary binding sites. At 37C and pH 7.4, the apparent association constant for binding of FFA to the primary site was of the order of 10⁵ M⁻¹ and that for binding to the secondary sites was approximately 10³ M⁻¹. The strength of binding was: palmitate > stearate > oleate > laurate. The affinity of BLG for palmitate increased as the pH of the incubation medium was raised from 6.5 to 8.7 and decreased as the ionic strength of the medium was raised. Palmitate binding was decreased in the presence of 6 M urea and when the protein either was exposed to elevated temperature or was acetylated prior to incubation. BLG took up methyl palmitate, cetyl alcohol, hexadecane and cholesterol to a lesser extent than FFA. Binding of FFA to BLG was associated with a small increase in the intensity of the fluorescent emission of the protein at 333 mμ. BLG can serve as an FFA acceptor or carrier in biological experiments. FFA released from adipose tissue during in vitro incubation was taken up by BLG. Net transfer of fatty acid to the incubation medium ceased when the molar ratio of FFA to BLG exceeded 1.1.¹⁴C-1-Palmitate bound to BLG was taken up by Ehrlich ascites tumor cells in vitro. At a given palmitate-protein molar ratio, much more labeled fatty acid was taken up by these cells from media containing BLG than from those containing bovine albumin, apparently because FFA is bound less firmly to BLG than to albumin. Special abbreviations used in this text: ν, average molar ratio of bound FFA to total protein; c, molar concentration of FFA in free solution and in equilibrium with that bound to protein; n, number of binding sites in a given class; k’, apparent association constant for binding to a given class of sites.     

Quality of subcutaneous,intermuscular and intramuscular fat tissue using elevated quantities of medium chain fatty acids in pig fattening

The present study comprised fat tissue samples of 46 (partly 23) pig carcasses randomly obtained from each one of four production systems: common fattening, pigs fattened on a low-fat diet and pigs grown on diets enriched with medium chain fatty acids (MCFA) in low or high amounts (0.3% and 3.6% C₈ with C₁₄, respectively). As models for subcutaneous, intermuscular and intramuscular fat tissues, back fat, dissected belly fat tissue and belly meat were used. In all fat tissues, the contents of MCFA were significantly elevated only with the high dietary content of MCFA, with a preferential retention of the MCFA in the storage tissues. In the MCFA supplemented groups, linoleic acid contents were slightly lower in subcutaneous and intermuscular fat as compared to the control group, in the group with the low-fat diet linoleic acid was considerably lower in all tissues. In spite of the only marginal differences in fatty acid pattern, the penetrometrically assessed firmness of backfat as well as the oxidative resistance of back and belly fat were almost twice as high in the high-MCFA group as in the other groups. In the low-fat group, water content of the back fat (16.9%) was higher than the average of the other groups (14.5%). The implications for routing assessment of fat tissue properties at slaughter plants are discussed.     

Selective uptake of fatty acids by the yeast Yarrowia lipolytica

Yarrowia lipolytica, when cultivated on mixtures of free fatty acid substrates was found to remove C12:0, C14:0, ^Δ9C18:1, ^{Δ9, 12}C18:2 and ^{Δ9, 12, 15}C18:3 at significantly higher rates than C16:0 and C18:0, regardless of fatty acid composition of the initial substrate. C12:0, C14:0 and ^{Δ9, 12, 15}C18:3 were specifically and completely removed from the substrate, while ^Δ9C18:1 and ^{Δ9, 12}C18:2 concentrations decreased by 55‐80 wt‐% in comparison with initial concentrations. In contrast, concentration of C18:0 increased 2.1—3.5 fold in the substrate. Although C18:0 was removed slowly from the substrate, this fatty acid was selectively accumulated in the storage lipid. Inversely, only low quantities of ^Δ9C18:1 and ^{Δ9, 12}C18:2 and traces of C12:0, C14:0 and ^{Δ9, 12, 15}C18:3 were accumulated in the storage lipid. During storage lipid breakdown, cellular C16:0 and ^Δ9C18:1 were taken up more rapidly than C18:0. We concluded that the capability of Yarrowia lipolytica to selectively remove several fatty acids from the substrate and accumulate others could be used in modification of the composition of selected mixtures of fatty acids and probably of common fats, to produce “new” fats with a predetermined composition.     

Fecal long chain fatty acids and colon cancer risk

To determine whether excretion of high concentrations of long chain fatty acids might be associated with high colon cancer risk, we compared concentrations of major long chain fatty acids in the feces of four populations at different risk for colon cancer. Concentrations of C18∶1 were found to be significantly higher (P<0.05) in the feces of the two high risk populations than in the feces of the two low risk populations.     

Chromatographic analysis of sucrose esters of long chain fatty acids

The procedure of the quantitative analysis of the components of sucrose ester products is described. By thin-layer chromatography, sucrose ester products have been separated into their components: mono-,di-,tri-, and higher esters. The individual components have been extracted from the plate and determined colorimetrically by using anthrone reagent. Standard substances of monoesters, diesters and triesters, which have been synthesized from gas-chromatographically pure methyl esters of fatty acids, have been isolated by column chromatography and identified by elemental analysis, colorimetric determination and N.M.R. determination.     

Serum fatty acid profiles after intravenous medium chain triglyceride administration

The serum fatty acid profiles of patients receiving either intravenous medium or long chain triglycerides were studied. Seventeen hospitalized patients, dependent on total parenteral nutrition, were randomly enrolled into a prospective study. The total parenteral nutrition (TPN) delivered amino acids and glucose and either a 75% medium chain triglyceride and 25% long chain triglyceride (MCT group) physical mixture or all long chain triglyceride (LCT group), as the respective fat sources. The amino acids and glucose were given continously, and the lipid was given for 10 hours each day over five days. Fatty acid profiles on serum triglycerides and free fatty acids were done in the morning before any lipid was given and also later in the afternoon, near the end of the lipid administration, on days 1, 3 and 5. Medium chain fatty acids rose quickly in the triglyceride fraction in patients given MCT. Rapid MCT hydrolysis occurred as evidenced by the appearance of medium chain fatty acids in the free fatty acid fraction in the afternoon sampling. Clearance of the hydrolyzed medium chain free fatty acids (MCFFA) occurred so that little, if any, were present in the morning sampling one day later. Long chain fatty acids, as either triglycerides or free fatty acids, showed expected increases during the daily infusion, but not of such relative magnitude as the medium chain fatty acids. Medium chain fatty acid incorporation into the phospholipid or cholesterol ester fractions by the end of the five-day feeding period was present but minimal. As opposed to conventional long chain triglycerides, intravenously administered medium chain triglycerides are hydrolyzed and cleared rapidly and do not accumulate in other lipid fractions, and are therefore a more readily available lipid fuel.     

N,N-dialkylamides of long chain fatty acids as plasticizers

A number of N,N-dialkylamides have been prepared, characterized and evaluated as plasticizers for poly (vinyl chloride-vinyl acetate) copolymer. Among these are the N-oleoyl derivatives of diisopropyl, dibutyl, diisobutyl, diamyl, dihexyl, diheptyl, dioctyl, di-2-ethylhexyl and didecylamines. Also included are the N,N-dibutylamides of 2-ethylhexanoic, neodecanoic, neotridecanoic, palmitic, stearic, linoleic, erucic, ricinoleic, naphthenic, dimer, pinic, epoxystearic, animal, cottonseed, hydrogenated cottonseed, rapeseed,Limnanthes douglasii seed and parsley seed acids. Optimum low-temperature plasticizing properties are achieved for the N-oleoyl derivatives of dibutyl, diamyl and dihexyl amines. These low-temperature properties are comparable to those of the adipate and sebacate plasticizers without the adverse volatility characteristics of the adipates. Compatibility of the N,N-dialkyloleamides extends through the dihexyl derivative. A brief heat stability study of some selected plasticized polylvinyl chloride copolymer compositions indicates that the thermal stabilization of amide plasticizers is not an insurmountable problem. Presented at the AOCS Meeting at Houston, Texas, April 1965. Laboratory of the So. Utiliz. Res. Devel. Div., ARS, USDA.     

Very long chain fatty acids in higher animals—A review

Fatty acids with greater than 22 carbon atoms (very long chain fatty acids, VLCFA) are present in small amounts in most animal tissues. Saturated and monoenoic VLCFA are major components of brain, while the polyenoic VLCFA occur in significant amounts in certain specialized animal tissues such at retina and spermatozoa. Biosynthesis of VLCFA occurs by carbon chain elongation of shorter chain fatty acid precursors while β-oxidation takes place, almost exclusively in peroxisomes. Mitochondria are unable to oxidize VLCFA because they lack a specific VLCFA coenzyme A synthetase, the first enzyme in the β-oxidation pathway. VLCFA accumulate in the tissues of patients with inherited abnormalities in peroxisomal assembly, and also in individuals with defects in enzymes catalyzing individual reactions along the β-oxidation pathway. It is believed that the accumulation of VLCFA in patient tissues contributes to the severe pathological changes which are a feature of these conditions. However, little is known of the role of VLCFA in normal cellular processes, and of the molecular basis for their contribution to the disease process. The present review provides an outline of the current knowledge of VLCFA including their biosynthesis, degradation, possible function and involvement in human disease.     

Production of 3R-hydroxy-polyenoic fatty acids by the yeast Dipodascopsis uninucleata

Various fatty acids were fed to the yeast Dipodascopsis uninucleata UOFS Y 128, and the extracted samples were analyzed for the accumulation of 3-hydroxy metabolites with the help of electron impact gas chromatography-mass spectrometry. Fatty acids containing a 5Z,8Z-diene system (5Z,8Z,11Z-eicosatrienoic, 5Z,8Z,11Z,14Z-eicosatetraenoic, and 5Z,8Z,11Z,14Z,17Z-eicosapentaenoic acids) yielded the corresponding 3-hydroxy-all-Z-eicosapolyenoic acids. Moreover, linoleic acid (9Z,12Z-octadecadienoic acid) and 11Z,14Z,17Z-eicosatrienoic acid were converted to the 3-hydroxylated metabolites of shorter chain length, e.g., 3-hydroxy-5Z,8Z-tetradecadienoic acid and 3-hydroxy-5Z,8Z,11Z-tetradecatrienoic acid, respectively. In contrast, no accumulation of a 3-hydroxy metabolite was observed with oleic acid (9Z-octadecenoic acid), linolelaidic acid (9E,12E-octadecadienoic acid), γ-linolenic acid (6Z,9Z,12Z-octadecatrienoic acid), and eicosanoic acid as substrate. These findings pinpoint that the 3-hydroxylation of a fatty acid in Dipodascopsis uninucleata requires a 5Z,8Z-diene system either directly or following initial incomplete β-oxidation. Following analysis of the enantiomer composition, the arachidonic acid metabolite was identified as 3R-hydroxy-5Z,8Z,11Z,14Z-eicosatetraenoic acid, which rules out a normal β-oxidation as biosynthetic route to this new class of oxylipins.