Saturated Fatty Acid Esters Research Articles

Extraction of polyunsaturated fatty acid ethyl esters from sardine oil using Ag +-containing o/w/o emulsion liquid membranes

Using silver ion as a carrier in o/w/o type emulsion liquid membranes, batch-wise extraction experiments were performed to separate polyunsaturated fatty acid ethyl esters originating in sardine oil. It was possible to separate polyunsaturated fatty acid (PUFA) esters from the mixture of PUFA and saturated fatty acid esters. The operating conditions for stable liquid membranes were experimentally determined. A new membrane breakage model that successfully describes the membrane stability behavior is proposed.

Preparing nontoxic microemulsions

In two Letters published earlier in this journal, we have presented recipes for preparing nontoxic microemulsions with unsaturated fatty acid alkyl esters, biological amphiphiles, and alkane-1,2-diols as cosolvents. In this paper we summarize the results and add some new ones, using a saturated fatty acid ester (isopropyl myristate), as well as an essential oil (orange oil).

Analysis of hydroxylated fatty acids from plant oils

AbstractA novel process has been described recently for the preparation of hydroxylated fatty acids (HOFA) and HOFA methyl esters from plant oils. HOFA methyl esters prepared from conventional and alternative plant oils were characterized by various chromatographic methods (thin‐layer chromatography, high‐performance liquid chromatography, and gas chromatography) and gas chromatography‐mass spectrometry as well as1H and13C nuclear magnetic resonance spectroscopy. HOFA methyl esters obtained fromEuphorbia lathyris seed oil, low‐erucic acid rapeseed oil, and sunflower oil contain as major constituents methylthreo‐9,10‐dihydroxy octadecanoate (derived from oleic acid) and methyl dihydroxy tetrahydrofuran octadecanoates, e.g., methyl 9,12‐dihydroxy‐10,13‐epoxy octadecanoates and methyl 10,13‐dihydroxy‐9,12‐epoxy octadecanoates (derived from linoleic acid). Other constituents detected in the products include methyl esters of saturated fatty acids (not epoxidized/derivatized) and traces of methyl esters of epoxy fatty acids (not hydrolyzed). The products that contain high levels of monomeric HOFA may find wide application in a variety of technical products.

Antimicrobial activity of shredded carrot extracts on food‐borne bacteria and yeast

Purified ethanolic extracts of peeled and shredded carrots showed an antimicrobial effect against a range of food-borne micro-organisms. The minimum inhibitory concentration, expressed as mg ml-1 dried carrot material used for the extraction were: Leuconostoc mesenteroides, 27; Listeria monocytogenes, > 27 < 55; Staphylococcus aureus, > 27 < 55; Pseudomonas fluorescens, > 55 < 110; Candida lambica, > 55 < 110; Escherichia coli, > 110 < 220. The antimicrobial activity was not linked to phenolic compounds but was presumably due to apolar components. Free saturated fatty acid (dodecanoic acid) and methyl esters of saturated fatty acids (of dodecanoic and pentadecanoic acids) were identified in purified active extracts of carrots by gas chromatography coupled to mass spectrometry and could be responsible for the antimicrobial activity. This effect did not seem to play a role in the resistance of shredded carrots to microbial spoilage, although the antimicrobial activity was present in fresh carrots at concentrations sufficient to inhibit spoilage bacteria.

Specificities of immobilized Geotrichum candidum CMICC 335426 lipases A and B in hydrolysis and ester synthesis reactions in organic solvents

Geotrichum candidum CMICC 335426 was previously shown to produce two lipases, lipase A and lipase B, lipase B being highly specific for hydrolysis of esters of cis-Δ9 fatty acids. We now describe the behavior of immobilized lipases A and B in organic solvents. Ester synthesis reactions were run in petroleum ether, and hydrolysis reactions were carried out in tri- n-butylphosphate containing water. The rates of hydrolysis measured in the organic solvent system were much lower than those observed with aqueous emulsions of the substrates, but the system allowed use of high-melting-point substrates in a liquid state. The immobilized lipases in organic media were found to have the same specificities as the free lipases acting on aqueous emulsions of the substrates. Lipase B was highly specific for (esters of) unsaturated fatty acids with a cis-double bond in the 9-position, but also catalyzed to some extent reactions involving (esters of) the saturated 8 :0 fatty acid; lipase A was much less specific and used a wider range of substrates including (esters of) saturated fatty acids and oleic acid isomers. We obtained specificity constants ( k cat K m ) for the lipase-catalyzed esterification of a few fatty acids, and confirmed the specificties of the lipases.

The enrichment of n−3 polyunsaturated fatty acids using aminopropyl solid phase extraction columns

A rapid, simple and reliable method is described for the preparation of concentrates of methyl or ethyl esters of n-3 polyunsaturated fatty acids by solid phase extraction using aminopropyl bonded silica columns. After applying mixtures of fatty acid esters in hexane, saturated and monounsaturated fatty acid esters are preferentially eluted with hexane whereas polyunsaturated fatty acids (PUFA) can subsequently be eluted with dichloromethane. Concentrates containing 80-90% n-3 PUFA can thus be obtained using fish oil fatty acids esters as a starting material.

Action of Fatty Acid Esters of l-Ascorbic Acid as Antioxidants in Phosphatidylcholine Liposomal Membranes

Abstract The antioxidant activities of saturated fatty acid esters of l-ascorbic acid were studied in the oxidations of soybean phosphatidylcholine liposomes in aqueous dispersions aiming at elucidating their action as antioxidants in the liposomal membranes, especially the effects of number and length of the fatty acid ester side chains at either 6- or both 5- and 6-positions. Ascorbic acid esters were found to act as radical-scavenging antioxidants in the oxidations initiated by either aqueous free radical attacking from outside of the membrane or by lipophilic radical generated within the membranes. They inhibited the oxidation cooperatively with α-tocopherol in the membranes and reduced the rate of α-tocopherol consumption, their sparing effects on α-tocopherol being greatest for the monoesters and for the esters with the shortest fatty acid chains within the diester group. It was concluded that the intramembrane and intermembrane mobilities of ascorbic acid esters decreased with increasing number and length of fatty acid chains.

Fatty acid specificity of bile salt-dependent lipase: enzyme recognition and super-substrate effects

A putative fatty acid specificity of bile salt-dependent lipases (BSDLs) has been re-investigated. The strategy was to use two evolutionally distant, homologous BSDLs (from human and cod), and to investigate their hydrolysis of different fatty acid esters at different assay conditions affecting the physicochemical phase of the substrate. Depending on assay conditions, large variations were seen in the hydrolysis rate for esters of different fatty acids. The two enzymes displayed similar fatty acid specificity patterns, with small, but significant differences that were maintained at various assay conditions. Compared to the human enzyme, the cod enzyme showed a preference for hydrolysis of long-chain polyunsaturated fatty acyl esters (up to 22 carbons in length). On the other hand, the human enzyme hydrolysed esters of shorter chain saturated fatty acids at significantly higher rates compared to the cod enzyme. Changing physicochemical factors affecting the substrate phase induced large changes in fatty acid specificity that affected both enzymes in similar manners. It is concluded that though the aliphatic chains of the fatty acids may not be recognized by the enzymes, these chains indirectly affect the conformation or interfacial availability of the carboxyl ester bond in the substrate, and the enzymes show minor specificities for variations in these structures.

Inhibition of hepatic glutathione- S-transferases by fatty acids and fatty acid esters

Micromolar concentrations of polyunsaturated fatty acids and ascorbate esters of saturated fatty acids were found to cause a marked inhibition of rat and mouse hepatic glutathione- S-transferase (GST) activity towards 1-chloro-2,4-dinitrobenzene. Arachidonic acid was approximately 25 times more potent in inhibiting rat GST than palmitic acid which was the least effective. Both linoleic and arachidonic acids did not inhibit rat liver GST when ethacrynic acid was used as substrate while the reverse was true with 1,2-dichoro-4-nitrobenzene. In contrast, all the chemicals tested inhibited rat liver GST activity towards 4-nitropyridine N-oxide, indicating isozyme specificity.

Structural Analysis of 9-Acridinylmethyl Derivatives of Fatty Acids by Mass Spectrometry

Characterization of electron impact mass spectra of 9-acridinylmethyl esters of fatty acids was reported. The esters gave molecular ions with relatively strong intensity and simple fragmentation patterns. Fragmentation ions appeared with 14 mass unit separations in the spectra of saturated fatty acid esters. In the spectra of unsaturated fatty acid esters, the 26 mass unit separations were observed at the position of double bonds in the molecule. Ions (M-30)+ and (M-31)+ suggested the existence of a hydroxymethyl group and the 29 and 30 mass unit separations suggested the positions of hydroxy groups located in the molecule. These fragmentations were useful for the structural analysis of fatty acids.

ChemInform Abstract: Metabolites of Microorganisms. Part 251. The Esmeraldins A and B, Dark‐Green Pigments from Streptomyces antibioticus, Strain Tue 2706.

AbstractIn contrast to saphenamycin (III) esmeraldin A (isolated as a mixture of higher saturated and unsaturated fatty acid esters (Ia)‐(Id) of esmeraldic acid) and esmeraldin B (II) do not reveal antibacterial activity.

Study of lipid peroxyl radicals in urea clathrate crystals: oxygen-17 couplings and rotational averaging

This work reports an electron spin resonance investigation of radicals formed after irradiation of a variety of fatty acid esters trapped in urea clathrate structures. Irradiation of saturated fatty acid esters results in carbon-centered radicals at the {alpha}-carbon site, whereas for unsaturated species the expected allylic and bisallylic radicals are found. Exposure of the carbon-centered radicals to oxygen results in their conversion to the corresponding peroxyl radicals. Orientation- and temperature-dependence studies show that at room temperature both the lipid carbon centered and peroxyl radicals rotate or oscillate in urea channels about their long axis. The rotational jump mechanism found for peroxyl radicals in this work usually follows the trigonal symmetry of the low-temperature distorted urea host channels. At room temperature the entrapped molecules rotate freely on their long axis, and as a consequence orientation of samples at the magic angle (54.7{degree}) gives isotropic couplings. Oxygen-17 labeling of the peroxyl radicals results in the first reported anisotropic oxygen hyperfine couplings for lipid peroxyl radicals.

Gas chromatographic-mass spectral studies after methylation of metabolites produced by some anaerobic bacteria in spent media.

The gas chromatographic analysis of metabolites such as volatile fatty acids (VFAs) and non-volatile fatty acids (NVFAs) for identification of anaerobic bacteria is now widely performed. Cultures of anaerobes tested for NVFAs as methyl esters were found to contain several unidentified compounds not previously detected and/or reported with methylation procedures. Gas chromatographic-mass spectrometric studies demonstrated that these compounds correspond to the methyl esters of both saturated and unsaturated short-chain fatty acids, and also of 2-hydroxy and 2-oxo acids. The distribution of these acids among different species of anaerobes was determined and their amounts were measured. The effects of supplementing the culture medium with either glucose or amino acids on the production of these acids are described. The use of very polar stationary phases is suggested for a better separation of all NVFAs.

Stoffwechselprodukte von Mikroorganismen. 251. Mitteilung. Die Esmeraldine A und B, tief grüne Farbstoffe aus Streptomyces antibioticus, Stamm Tü 2706

The Esmeraldines A and B, Green Pigments from Streptomyces antibioticus, Strain Tü 2706From a strain of Sterptomyces antibioticus, Tü 2706, two dark green substances, the esmeraldines A and B, 4 and 3, respectively, were isolated. The structural elucidation was carried out by spectroscopic comparison with some simpler phenazines obtained from the same organism, saphenamycin (1) and related compounds, and by a series of chemical transformations. Esmeraldin B (3) is the 6‐methylsalicylic acid ester, and esmeraldin A (4) a mixture of higher saturated and unsaturated fatty acid esters of esmeraldic acid. The latter is a heterocyclic compound with seven rings and four N‐atoms, formally derived by condensation of two phenazine residues of the saphenic acid family. The esmeraldins are mixtures are of diastereoisomers.

Cholesteryl esters of saturated fatty acids: cosolubility and fractionation of binary mixtures

Factors affecting the solid state miscibility of saturated chain cholesteryl esters were determined from electron diffraction and differential scanning calorimetric measurements on a homologous series which included two types of crystal packing. Electron diffraction patterns from solution- and epitaxially crystallized microcrystals gave measured unit cell constants consistent with the bilayer crystal form for myristate, pentadecanoate, palmitate, and stearate esters. Cholesteryl undecanoate crystallized as the monolayer I structure and cholesteryl laurate was polymorphic, packing in either monolayer I or bilayer forms. No evidence was found for the monolayer II form of the laurate claimed in earlier work. It is clear that solid solution formation follows general rules formulated earlier by Kitaigorodskii for molecular crystals. A symmetry criterion must be satisfied first of all, i.e., two compounds that solidify in greatly different crystal structures will not form continuous solid solutions (e.g., cholesteryl undecanoate/cholesteryl myristate). Within a given crystal structure type, solid solution is permitted when the molecular volumes are similar. (For example, cholesteryl myristate forms an ideal solid solution with cholesteryl pentadecanoate, a nonideal solution with cholesteryl palmitate, and a eutectic of solid solutions with cholesteryl stearate.) For the polymorphic cholesteryl laurate, solid solutions of either the monolayer I structure (e.g., with cholesteryl undecanoate) or bilayer structure (e.g., with cholesteryl myristate) are permitted.

Purification and characterization of a carboxylesterase from rabbit liver lysosomes.

Carboxylesterase [EC 3.1.1.1] was purified from rabbit liver lysosomes by means of detergent solubilization, and by hydroxyapatite, phenyl-Sepharose and chromatofocusing column chromatographies. The purified enzyme appeared to be homogeneous on SDS-polyacrylamide gel electrophoresis and its molecular weight was estimated to be 58,000. This enzyme was eluted at an isoelectric point of approximately 5.8 by chromatofocusing, and exhibited a broad pH optimum of between 6.0 and 9.0. The enzyme hydrolyzed 4-methylumbelliferyl esters of saturated fatty acids (C2-C12), and it also hydrolyzed p-nitrophenylacetate, methyl butyrate, and tributyrin, but not acetanilide. Its activity was completely inhibited by diisopropyl-fluorophosphate (DFP) and phenylmethylsulfonyl fluoride (PMSF) at 10(-4) M, but was not affected by eserine, or by alpha- or beta-naphthyl acetate at 10(-3) M. Various metal ions (Mg2+, Mn2+, Ca2+, Co2+, Cu2+, Zn2+, Ni2+) at 10(-3) M also had no effect on the enzyme activity.

Covalent adduct formation and chloroform production after free radical attack on fatty acids by carbon tetrachloride reactive intermediates

The interactions of fatty acids and the trichloromethyl free radical generated anaerobically by the benzoyl peroxide model system were studied. Chloroform was produced due to the interaction of the trichloromethyl free radical with the unsaturated fatty acid ester methyl oleate, indicating the hydrogen in chloroform may result from abstraction from fatty acids. In addition, choloroform was detected in incubations containing the saturated fatty acid ester methyl stearate, indicating hydrogen abstraction is not limited to allylic hydrogens. Mass spectral analysis identified one adduct resulting from additional reactions to methyl oleate, and an adduct resulting initially from hydrigen abstraction on methyl stearate. These findings describe previously unreported reactions of the trichloromethyl free radical with saturated fatty acid, and inhibition of chloroform production by 3 free radical inhibitors.

Fatty Acids and Retinyl Esters of Rat Milk: Effects of Diet and Duration of Lactation

This study was initiated to explore the quantitative and qualitative differences in milk total fatty acids and milk retinyl esters when either hydrogenated or nonhydrogenated fat is fed during pregnancy and lactation. Rats were fed diets containing 10% by weight of corn oil or partially hydrogenated corn oil. Milk was collected on d 1, 8 and 14 of lactation and analyzed for protein, total fatty acids, fatty acid pattern, and retinyl ester pattern. Whereas diet produced no quantitative differences in milk protein or total fatty acids, the pattern of milk fatty acids varied significantly. Rats fed corn oil produced milk having more medium-chain saturated fatty acids, less long-chain monoenoic fatty acids, and more polyunsaturated fatty acids compared to those fed hydrogenated corn oil. Rats fed hydrogenated corn oil produced milk fat having 21–26% of the trans fatty acid, elaidic acid. Significant differences were also observed with duration of lactation: medium-chain fatty acids increased three to fourfold between d 1 and 8, where cis-monoenes and polyunsaturated fatty acids declined. The pattern of milk retinyl esters strongly reflected, but was not identical to, that of total milk fat. Comparing d 14 milk from rats fed corn oil with that from rats fed hydrogenated corn oil, medium-chain esters of retinol constituted 24 and 11% of total retinyl esters, whereas saturated long-chain fatty acid esters constituted 52 and 44%, respectively. trans Fatty acid esters of retinol comprised 24% of vitamin A esters in milk of rats fed hydrogenated fat. These data provide evidence that the composition of milk retinyl esters, as well as that of total milk fat, is determined both by the type of fatty acids from diet and from diet-related differences in de novo synthesis of fatty acids within the mammary gland and other tissues.

Structural and communicative functions of Dufour's gland secretion in Eucera palestinae (Hymenoptera; Anthophoridae)

Dufour's gland secretion of Eucera palestinae (Friese) is composed of hydrocarbons, and methyl esters of saturated and unsaturated fatty acids. The secretion is used to line the brood cell walls making them hydrophobic. In addition it provides the nest with an individual odour. This nest specific odour helps the bees to locate their own nests in a dense aggregation of nests.

Trans Fatty acids in milkfat

AbstractMilkfat is extremely complex, with ca. 500 different fatty acids reported in the triglycerides. Seasonal feed variation results in higher unsaturated fatty acid levels in summer than in winter. Rumen microbes hydrogenate unsaturated feed lipids to yield a mixture of geometrical and positional isomers which are transmitted to the milk. Total isolatedtrans fatty acids in milkfat reported in the literature range from 2 to 11% with maximal values in summer and minimal values in winter. A study was undertaken about the use of AOCS Method Cd 14‐61 for the determination of isolatedtrans levels in milkfat. The triglycerides of milkfat were analyzed using trielaidin as a standard and milkfat methyl esters were analyzed using methyl elaidate as a standard. Corrections were made, for the loss of the methyl esters of the short‐chain fatty acids. The apparent levels oftrans found by using the triglycerides were considerably higher than by using the methyl esters. Infrared spectra of pure triglycerides of saturated fatty acids showed measurable absorption at 10.36 μm, whereas methyl esters of saturated andcis unsaturated fatty acids did not.