Fatty acids of doxantha seed oil

The seed oil ofDoxantha unguis-cati was found to have the following fatty acid composition:cis-9-hexadecenoic 64,cis-11-octadecenoic 15, oleic 4, hexadecadienoic 1, linoleic 4, palmitic 12 and stearic <1%. The significance of the unusual fat composition is discussed in relation to biosynthetic mechanisms. Issued as NRC No. 8291.     

The absorption of fatty acids by functional bovine mammary cells

Freshly dispersed bovine mammary cells rapidly absorbed long chain fatty acids from the culture medium. Differences in the rates of absorption were observed, i.e., palmitic > stearic > oleic > myristic > linoleic acid. The preponderance of the fatty acids absorbed were esterified into triglycerides (>75%) and the remainder were mostly incorporated into phospholipids. The cells secreted triglycerides into the culture medium. Of the phospholipid classes, phosphatidylcholine always contained most of the radioactivity in all experiments with labeled fatty acids. These observations are related to the metabolism of mammary cells in vivo.     

Rapid transesterification and mass spectrometric approach to seed oil analysis

Fatty acid composition of seed oil is determined in less than one hr using a quantitative one-vial technique. The method of analysis requires alcoholic solutions of sodium methoxide mild enough for epoxy and polyunsaturated oils. Separation and characterization of component fatty acids were accomplished by high resolution gas chromatography-mass spectrometry. Using this method,Vernonia galamensis seed oil is shown to contain 79–80% vernolic (cis-12,13-epoxy-cis-9-octadecenoic) acid.Amaranthus cruentus, a West African vegetable crop, is shown to contain 17.3% palmitic acid, 3.2% stearic acid, 22.7% oleic acid, 54.7% linoleic acid and 2.1% linolenic acid.     

Fatty acid biosynthesis in the developing endosperm ofCocos nucifera

Endosperm tissue of developing coconut endosperm incorporated [¹⁴C] acetate and [¹⁴C]-malonate into [¹⁴C]C₈-C₁₈ fatty acids. The distribution of [¹⁴C] label into the various fatty acids mimicked the distribution of endogenous fatty acids at early and middle stages of endosperm development. Although [¹⁴C] C₈-C₁₈ fatty acids were taken up rapidly by endosperm tissue slices, no elongation occurred; [¹⁴C] stearic acid was not desaturated to oleic. Cell free preparations have also been obtained from this tissue that readily incorporated [¹⁴C] malonyl-CoA into a range of [¹⁴C] fatty acids in the presence of ACP and NADH at pH 7.0. Employing this system, a number of experiments were designed to determine the mechanism of chain length termination. In contrast to intact tissue slice experiments, cell-free extracts yielded as principal products palmitic and stearic acid, although up to 20% were shorter chain acids. A number of possible mechanisms for chain length termination were proposed and tested. Supported in part by NSF Grant No. PCM76 01495.     

Cis-5-monoenoic fatty acids ofCarlina (Compositae) seed oils

Seed oils ofCarlina corymbosa L. andC. acaulis L. containcis-5-octadecenoic acid as a major fatty acid (21–24%). This acid has not been previously reported as a constituent of Compositate seed oils. The predominant fatty acid in theCarlina oils is linoleic (50–52%); lesser amounts (≦10% each) of palmitic, stearic and oleic acids are also present. The oil ofC. acaulis has almost 2% ofcis-5-hexadecenoic acid;C. corymbosa oil includes minor amounts of some oxygenated fatty acids. Presented at the AOCS Meeting, New York, October 1968. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Synthesis of octadecynoic acids and [1-14C] labeled isomers of octadecenoic acids

Geometric and positional isomers of [1-¹⁴C] octadecenoic acids have been synthesized by modifications of published procedures. Positional isomers of octadecynoic acids also have been synthesized to obtain the geometric and positional isomers of the unlabeled octadecenoic acid analogs. The syntheses were accomplished by coupling a haloalkyl compound with a substituted acetylene using n-butyl lithium in hexamethylphosphoramide. The coupled product, either a 17-or 18-carbon acetylenic alcohol, could be semihydrogenated and chain extended to afford a carboxy labeled derivative, could be partially hydrogenated and chain extended to afford a carboxyl labeledcis-ortrans-octadecenoic acid in the former case. In the latter case, octadecynoic,cis-octadecenoic ortrans-octadecenoic acids could be obtained by the appropriate reactions. The methods used in this study enabled the synthesis of¹⁴C-labeled fatty acids in generally higher yields and by simpler reactions than were previously possible.     

Factors affecting fatty acid oxidation in bovine mammary tissue

Oxidation of fatty acids was studied in bovine mammary tissue slices in order to evaluate their potential contribution to energy metabolism. Rates of fatty acid oxidation decreased with increasing chain length: acetate>octanoate>palmitate or oleate. Rates of oxidation of long chain, but not short chain, fatty acids increased over time, which could not be explained by carnitine palmitoyltransferase (CPT) activity. This phenomenon is not an artifact of the incubation system or caused by substrate solubility, as rates of palmitate oxidation were constant in rat kidney cortex slices. Preincubating mammary tissue with or without unlabeled palmitate showed that increasing rates of palmitate oxidation is not caused by use of endogenous fatty acids. Palmitate at 0.26 mM, equivalent to arterial fatty acid concentration, gave maximal rates of oxidation. The β-oxidation enzymes may restrict fatty acid oxidation as oxidation of [1-¹⁴C] palmitate exceeded that of [U-¹⁴C] palmitate. Acetate inhibited palmitate oxidation (75%) but not esterification, suggesting that acetate inhibits palmitate oxidation by substrate competition at the mitochondrial level or via malonyl-CoA inhibition of CPT. Glucose inhibited palmitate oxidation (67%) and stimulated esterification. Low palmitoyl-CoA levels would favor glyceride synthesis over oxidation, since the apparent K_m for palmitoyl-CoA, of the glycerol-3-phosphate acyltransferases is lower than that for CPT. Thus, glucose presumably diverts palmitate from oxidation to glycerolipids. Clofenapate, a glyceride synthesis inhibitor, decreased triacylglycerol formation, and marginally increased palmitate oxidation. We estimated that long chain fatty acids can potentially account for 6–10% of the oxidative metabolism of mammary tissue. Published with approval of the Director of the Agricultural Experiment Station as Journal Article No. 9292.     

Elongation of (n−9) and (n−7)cis-monounsaturated and saturated fatty acids in seeds ofsinapis alba

Lipids in developing seeds ofSinapis alba contain appreciable proportions of (n−7)octadecenoic (vaccenic) acid besides its (n−9) isomer (oleic acid), whereas the constituent very long chain (>C₁₈) monounsaturated fatty acids of these lipids are overwhelmingly composed of the (n−9) isomers. Cotyledons of developingSinapis alba seed use [1-¹⁴C]acetate, [1-¹⁴C]malonate or [1,3-¹⁴C]malonyl-CoA for de novo synthesis of palmitic, stearic and oleic acids and for elongation of preformed oleic, vaccenic and stearic acids to their higher (n−9), (n−7) and saturated homologs, respectively. Moreover, elongation of preformed (n−7)palmitoleic acid to vaccenic acid is observed. Stepwise C₂-additions to preformed oleoyl-CoA by acetyl-CoA or malonyl-CoA yielding (n−9)icosenoyl-CoA, (n−9)docosenoyl-CoA and (n−9)tetracosenoyl-CoA are by far the most predominant reactions catalyzed by the elongase system, which seems to have a preference for oleoyl-CoA over vaccenoyl-CoA as the primer. The pattern of¹⁴C-labeling of the very long chain fatty acids formed from either acetate or malonate shows a close analogy in the mode of elongation of monounsaturated and saturated fatty acids.     

Tissue culture of cocoa bean (Theobroma cacao L.): Incorporation of fatty acids into lipids of cultured cells

Suspension cell cultures of cocoa bean rapidly incorporated palmitic, stearic, oleic and linoleic acids into cellular lipids. Thus, 75 and 20% of [1-¹⁴C] palmitic acid was incorporated into polar lipids and triglycerides, respectively, after 48 hr. When [1-¹⁴C] oleic and [1-¹⁴C] linoleic acid were added separately, polar lipids consistently contained most of the radioactive fatty acids. Ca. 60% of the stearic acid accumulated as unesterified fatty acid in the cells. Palmitic and stearic acid were not desaturated, but oleic acid and linoleic acid were further desaturated. The kinetics of conversion of oleic acid and linoleic acid suggested a sequential desaturation pathway of 18∶1→18∶2→18∶3 in cocoa bean cell suspensions.     

The Influence of High Contents of Animal and Vegetable Fat in Concentrates on Rumen Fermentation Pattern and Milk Fatty Acid Composition in Dairy Cows

In two feedings trials with respectively fresh cows and cows in mid-lactation the animals received concentrates which provided ca. 400 g and 370 g fat from coconut and palmkernel expeller and palmkernels per day. The secretion of medium chain fatty acids with the milk was decreased as compared to cows on a control treatment. In the trial with cows in mid-lactation this decrease was compensated by a higher supply of the mammary tissue with lauric and myristic acid via the blood. The primary cause of the decreased secretion of medium chain fatty acids seems to be a disturbance of the rumen fermentation. A daily quantity of 345 or 620 g soyabean oil in ca. 13 kg concentrate also diminished the secretion of medium chain fatty acids in fresh cows. The negative effect of soyabean oil was probably partially caused by inhibition of the de novo synthesis of fatty acids in mammary tissue by long chain fatty acids, especially trans-isomers of C18-fatty acids. However, there were also indications of disturbance of rumen fermentation the more as the soyabean oil was mixed up the the free form as compared to soyabean oil in toasted soyabeans. Renderers fat and calcium salts of palmitic and oleic acid had a less negative effect on rumen fermentation. Still the secretion of medium chain fatty acids with the milk was decreased. This could be caused by inhibition of the de novo synthesis. The lowered production of medium chain fatty acids was compensated for or even exceeded by the extra supply of long chain fatty acids by the blood.     

Selective removal of free fatty acids in oils using a microorganism

A microorganism assimilating long chain fatty acids without secreting extracellular lipases was screened from soil and was identified as aPseudomonas. Growth factors, nitrogen sources and trace elements required for growth of the microorganism namedPseudomonas strain BG1 were determined. Optimum pH and growth temperature were 6 and 30°C, respectively. BG1 was found to utilize lauric, myristic, palmitic, stearic and oleic acids as carbon sources. BG1 was shown to utilize 0.1% oleic acid almost completely in an emulsion medium within 48 hr. When BG1 was grown in a mixture of triolein and oleic acid, it selectively removed the free fatty acid without loss of triolein and did not produce mono- and diglycerides.     

Zinc deficiency increases the rate of Δ6 desaturation of linoleic acid in rat mammary tissue

The effect of zinc deficiency on the Δ⁶-desaturation of [1-¹⁴C] linoleic acid was studied in mammary tissue microsomes from lactating rats. The rats were maintained on zinc-adequate (20 ppm zinc) or zinc-deficient (10 ppm zinc changing to 0.5 ppm zinc during last trimester) diets throughout gestation and for the first 3 days of lactation. Mammary tissue microsomes were incubated with [1-¹⁴C] linoleic acid and other samples of mammary tissue, mammary milk and the milk in the stomachs of the pups were analyzed for total fatty acid composition. In mammary microsomes from zinc-deficient rats, Δ⁶-desaturation of linoleic acid was 3.4 times greater than in microsomes from zinc-adequate rats. This change in metabolism of linoleic acid was reflected by comparable changes in the relative tissue and milk composition of linoleic and arachidonic acids and in the ratios of palmitic to palmitoleic acid, stearic to oleic acid and linoleic and arachidonic acid.     

The influence of dietary fat on the lipogenic activity and fatty acid composition of rat white adipose tissue

The in vivo fatty acid synthesis rate, selected enzyme activities and fatty acid composition of rat white adipose tissue from animals fed semisynthetic diets of differing fat type and content were studied. All animals were starved for 48 hr and then refed a fat-free (FF) diet for 48 hr. They were then divided into three groups. One group was continued on the FF diet for 48 hr. Another group was fed a diet containing 44% of calories from corn oil (CO). The final group was fed a diet containing 44% of calories from completely hydrogenated soybean oil (HSO). The animals on the FF diet had a marked increase in adipose tissue fatty acid synthesis during the 96-hr feeding peroid (as measured by³H incorporation into adipose fatty acids). Addition of either CO or HSO to the diets did not significantly inhibit fatty acid synthesis in dorsal or epididymal adipose tissue. The activities of the enzymes' fatty acid synthetase, ATP-citrate lyase and glucose-6-phosphate dehydrogenase increased on the FF diet and generally were not inhibited significantly by the addition of either fat to the diets. Linoleic acid was the major polyunsaturated fatty acid (ca. 22%) in adipose tissue. Monounsaturated fatty acids (palmitoleic, oleic,cis-vaccenic) made up ca 38% of the total adipose fatty acids, while saturated fatty acids accounted for about 32% (myristic, palmitic and stearic). White adipose tissue in mature male rats was a major depot for n−3 fatty acids. There were differences in the fatty acid composition of epididymal and dorsal adipose tissue, particularly in their content of long chain, polyunsaturated fatty acids with epididymal tissue containing more of these compounds than dorsal fat. The fatty acid composition of the white adipose tissue did not change significantly during fasting or 96 hr of refeeding the FF diets. The addition of HSO to the diet for 48 hr had little influence on the adipose tissue fatty acid composition, but the addition of CO to the diet caused a 7% increase in the dorsal adipose tissue linoleate content (as percentage of total dorsal adipose tissue fatty acids) within 48 hr compared to animals fed the stock diet and those starved for 48 hr. The fatty acid synthesis data indicated that adipose tissue in the rat can continue to be a source of de novo fatty acid synthesis in animals consuming high-fat diets.     

The effect of protein deficiency on some rat liver lipid metabolic enzymes and CoA

Two groups of male Wistar rats were fed normal (i.e., 18%) and protein-free diets, respectively, for 7 weeks. In vivo incorporation of [1-¹⁴C] acetate into palmitic, stearic, oleic, and arachidonic acids by the liver was reduced in the protein-deficient rats. In vitro incubation of liver microsomes with labeled palmitate or linoleate revealed no change in the specific activities of chain elongating or desaturating enzymes. Protein deficiency resulted in a decrease in specific activity of short chain acyl-CoA synthetase and in total CoA, accompanied by the virtual disappearance of acyl-CoA and an increase in free CoA. Furthermore, there was less microsomal fatty acid synthetase and mitochondrial β-hydroxybutyrate dehydrogenase activity. These results are discussed in relation to fatty acid synthesis and the changes in liver fatty acid composition.     

A study on the biosynthesis ofcis-9,10-epoxyoctadecanoic acid

Preliminary studies show that red stem, rust-infected wheat plants provide a means for investigating the biosynthesis of epoxy fatty acids. The incorporation of 1-¹⁴C-acetate intocis-9,10-epoxyoctadecanoic acid occurs at the stage of the infection when sporulation is proceeding, and at the same stage there is at least a fourfold increase in the synthesis of other fatty acids. The epoxy acid appears to be formed by the condensation of acetate units in a process that requires oxygen and is not stimulated appreciably by light. Labeled stearic and oleic acid are also incorporated into the epoxy acid without undergoing β-oxidation. The rate of conversion of oleic acid is greater than stearic acid, thus indicating that oleic acid is an immediate precursor to 9,10-epoxyoctadecanoic acid. Published with the approval of the director as Paper. No. 2161. Journal Series, Nebraska Agricultural Experiment Station.     

cis-5,cis-9,cis-12-octadecatrienoic and some unusual oxygenated acids inXeranthemum annuum seed oil

Seed oil ofXeranthemum annuum (family Compositae) contains a number of unusual fatty acids in addition to palmitic, stearic, oleic, linoleic and linolenic. These acids includecis-5,cis-9,cis-12-octadecatrienoic, 5%;cis-9-l,10-l-epoxyoctadecanoic, 3%;cis-9-l,10-l-epoxy-cis-12-octadecenoic (coronaric), 8%; andcis-12-d,13-d-epoxy-cis-9-octadecenoic (vernolic), 2%; as well as a mixture of two hydroxy acids, 11%. The absolute configurations of the two 9,10-epoxy acids are established for the first time. Presented in part at the AOCS Meeting in Cincinnati, October 1965. No. Utiliz. Res. Dev. Div., ARS, USDA.     

Isolation of cerebroside containing glucose (Glucosyl ceramide) and its possible significance in ganglioside synthesis

A small amount of cerebroside containing glucose (glucosyl ceramide) was isolated from bovine brain by Florisil column chromatography and thin-layer chromatography. The fatty acids of the glucosyl ceramide were palmitic and stearic acids; small amounts of oleic and linoleic acids were present. Rat brain tissue slices, incubated with U-¹⁴C-glucose, incorporated more radioacivity into glucosyl ceramide than into galactosyl ceramide. From these results the possible metabolic significance of the brain glucosyl ceramide in ganglioside metabolism is discussed.     

Vernonia galamensis: A rich source of epoxy acid

A percolation extraction ofVernonia galamensis seed, affording 38.6% of crude vernonia oil is described. The dark colored crude oil was degummed with water, treated with activated charcoal and bleached with a neutral agent, to give a light colored oil (Lovibond: 0.9 red, 3.5 yellow). Gas chromatographic/mass spectrometric analysis of the refined oil indicates a relative fatty acid composition of 79–81% vernolic (cis-12,13-epoxy-cis-9-octadecenoic) acid, 11–12% linoleic acid, 4–6% oleic acid, 2–3% stearic acid, 2–4% palmitic acid, and a trace amount of arachidic acid.     

Lipids of cultured hepatoma cells: VI. Glycerolipid and monoenoic fatty acid biosynthesis in minimal deviation hepatoma 7288C

1-14C-Acetic, 1-14C-palmitic, or 1-14C-stearic acid was incubated with minimal deviation hepatoma 7288C cells grown in culture to assess: de novo fatty acid synthesis, oxidation, desaturation, and elongation of saturated fatty acids, as well as the ability of media fatty acids to serve as precursors of cellular glycerolipids. Distribution of radioactivity in the individual lipid classes and the various fatty acids of triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine was determined. The radioactivity among the monoenoic acid isomers derived from triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine was analyzed by reductive ozonolysis. Only small amounts of the labeled substrates were oxidized to carbon dioxide. Except for labeled stearic acid, which also was incorporated heavily into phosphatidyl inositol and phosphatidyl serine, most radioactivity was recovered in triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine. Synthesis of cholesterol and long chain fatty acids from labeled acetic acid demonstrated that these cells can perform de novo synthesis of fatty acids and cholesterol. Both labeled palmitic and stearic acids were desaturated to the corresponding delta9 monoenes, and palmitic and palmitoleic acids were elongated. The nexadecenoic acid fraction isolated from triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine, when acetic or palmitic acid was the labeled substrate, showed that greater than 70 percent of the labeled acids were the delta9 isomer. Radioactivity of the octadecenoic acid fraction derived from labeled acetic or palmitic acids was nearly equally divided between the delta9 isomer, oleic acid, and the delta11 isomer, vaccenic acid. Desaturation of labeled stearic acid produced only oleic acid. These data demonstrate that the biosynthesis of vaccenic acid in these cultured neoplastic cells proceeds via the elongation of palmitoleic acid. The relatively high level of vaccenic acid synthesis in these cells suggests that the reported elevation of "oleic acid" in many neoplasms may result from increased concentration of vaccenic acid.     

Growth Temperature and Salinity Impact Fatty Acid Composition and Degree of Unsaturation in Peanut-Nodulating Rhizobia

Growth and survival of bacteria depend on homeostasis of membrane lipids, and the capacity to adjust lipid composition to adapt to various environmental stresses. Membrane fluidity is regulated in part by the ratio of unsaturated to saturated fatty acids present in membrane lipids. Here, we studied the effects of high growth temperature and salinity (NaCl) stress, separately or in combination, on fatty acids composition and de novo synthesis in two peanut-nodulating Bradyrhizobium strains (fast-growing TAL1000 and slow-growing SEMIA6144). Both strains contained the fatty acids palmitic, stearic, and cis-vaccenic + oleic. TAL1000 also contained eicosatrienoic acid and cyclopropane fatty acid. The most striking change, in both strains, was a decreased percentage of cis-vaccenic + oleic (≥80% for TAL1000), and an associated increase in saturated fatty acids, under high growth temperature or combined conditions. Cyclopropane fatty acid was significantly increased in TAL1000 under the above conditions. De novo synthesis of fatty acids was shifted to the synthesis of a higher proportion of saturated fatty acids under all tested conditions, but to a lesser degree for SEMIA6144 compared to TAL1000. The major adaptive response of these rhizobial strains to increased temperature and salinity was an altered degree of fatty acid unsaturation, to maintain the normal physical state of membrane lipids.