Oleic Acid Residues Research Articles

Sterically Hindered Triacylglycerol Analogues as Potent Inhibitors of Human Digestive Lipases

A novel class of inhibitors of human digestive lipases have been developed. Various sterically hindered triacylglycerols based on 2-methyl- and 2-butylglycerol, and/or 2-methyl fatty acids were synthesized. The triacylglycerol analogues were tested for their ability to form stable monomolecular films at the air/water interface by recording their surface-pressure/molecular-area compression isotherms. The inhibition of human pancreatic and gastric lipases by the sterically hindered triacylglycerol analogues was studied by using the monolayer technique with mixed films of 1,2-dicaprin, which contained variable proportions of each inhibitor. Triolein analogues that contain a butyl group at the 2-position of the glycerol backbone or methyl groups both at the 2-position of glycerol, and the alpha-position of each oleic acid residue were potent inhibitors; this caused a 50% decrease in HPL activity at 0.003 molar fraction.

Altered lipid cell membrane profile in children affected by atopic dermatitis

Rationale An abnormal essential fatty acid (EFAs) metabolism and a higher unsaturated trans FA (TFA) levels have been associated with allergy suggesting a link between fatty acid (FA) structures and atopic diseases. The aim of the present study was to correlate the atopic status with FA profile and TFA presence in cell membrane. Methods We studied the erythrocyte and T lymphocyte membranes obtained from 10 children affected by atopic dermatitis (AD). Total phospholipid fractions were analyzed by an innovative protocol made of two parallel gas chromatography (GC) analysis which include the cis/trans isomer identification of FA. Results In all patients the saturated/monounsaturated FA (SFA/MUFA) ratio was higher than normal range (1.7-2). The percentage of arachidonate 20:4 FA was normal but, in 3 patients, it was replaced by 20:3. The GC profile of C20 FA, compared with the profile of arachidonate isomerization, showed the presence of trans isomers at high levels . Moreover, trans isomer of oleic acid residues was also found in 50% of the patients and 20:5 (EPA) and 22:6 (DHA) FA were very low or absent in all the patients. Conclusions In erythrocyte and T cell membranes of our AD children a serious impairment of lipid metabolism was observed, consistent with a reduced rate of activity of delta 6 desaturase. The altered SFA/MUFA ratio together with the higher percentage of the trans isomeric forms might affect membrane structure or fluidity and consequently lead to an alteration of the immune receptor complexes within the lipid microdomains (rafts).

Efficient lipase catalysed production of a lubricant and surfactant formulation using a continuous solvent-free process

The transesterification of sunflower oil with a high oleic acid residue content (typically 83.5%) with butanol-1 by immobilised Lipozyme ® was carried out in a solvent free system and in a continuous way. During the first 6 h of reactor operation, a transition phase was observed, in which the main products were butyl ester and glycerol. This latter being insoluble in the reaction mixture, it is adsorbed onto the enzyme support thus leading to a decrease in enzyme performance. Step by step, less and less glycerol is produced and finally when glycerol is no longer produced a steady state is attained. The product composition is a mixture of butyl ester (65 molar%), monoglyceride (26 molar%), diglyceride (6 molar%) and residual triglyceride (3 molar%). This mixture has interesting lubricant and surfactant properties. The reactor was maintained without any loss in activity for a period of 3 months. This result is very different to that obtained using an organic solvent ( n-hexane) which leads to a total loss of enzyme activity within a few hours.

Interaction of exogenous hypochlorite or hypochlorite produced by myeloperoxidase + H2O2 + Cl- system with unsaturated phosphatidylcholines.

The interaction between unsaturated phosphatidylcholines and either exogenous or endogenous (produced by the enzyme system involving myeloperoxidase (MPO), H2O2, and Cl-) hypochlorite was studied in multilayer liposomes containing oleic, linoleic, and arachidonic acid residues using MALDI-TOF mass spectrometry. At pH 7.4, hypochlorite reacts with the double bond of the oleic acid residue in 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine producing oleic acid chlorohydrin as the main product. Minor amounts of glycols and epoxides were also detected. The main products of the reaction of hypochlorite with 1-stearoyl-2-linoleyl-sn-glycero-3-phosphocholine were mono- and di-chlorohydrins of linoleic acid. The signals of monoglycol, epoxide, and glycol- or epoxide-containing monochlorohydrin derivatives were also present in the mass spectrum. The main products of the reaction of hypochlorite with 1-stearoyl-2-arachidonyl-sn-glycero-3-phosphocholine were lysophosphatidylcholine (1-stearoyl-sn-glycero-3-phosphocholine) and mono-, di-, and trichlorohydrin. Monoglycol and its derivatives containing one or two chlorohydrin groups were also detected. Along with those, carbonyl compounds (aldehyde and acid) formed as a result of double bond breakage in fifth position of arachidonate were detected. Monochlorohydrin was also found when liposomes comprising 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine were incubated in the presence of enzymatic mixture, MPO + H2O2 + Cl-, at pH 6.0. In the absence of the enzyme or either of its substrates (H2O2 or Cl-) or in the presence of the MPO inhibitor (sodium azide) or hypochlorite scavengers (taurine or methionine), monochlorohydrin formation was not observed. These data confirm the suggestion that just the hypochlorite generated in MPO-catalysis provides for chlorohydrin formation. Thus, the use of MALDI-TOF mass spectrometry has shown, along with chlorohydrins, glycols and epoxides as the products of hypochlorite interaction with unsaturated phosphatidylcholines at physiological pH. It was first determined that hypochlorite breaks double bonds in polyunsaturated phosphatidylcholine and also causes lysophosphatidylcholine formation.

Antiradical and Antioxidant Activity of Phenylhydrazones of Aromatic Aldehydes

With the aim of searching for new antioxidants, including those of the biogenic type, the antioxidant properties of phenylhydrazones of some aromatic aldehydes were studied under conditions of ascorbatedependent peroxide oxidation of oleic acid residues in Tween-80. Also the reactivity of these hydrazones toward a stable radical, diphenylpicrylhydrazyl, was studied. The correlation between the antioxidant and antiradical activities of phenylhydrazones was examined.

Oleyl alcohol inhibits intestinal long-chain fatty acid absorption in rats.

Long-chain fatty acids are important nutrients, but obesity is the most common nutritional disorder in humans. In this study we investigated the effect of oleyl alcohol on the intestinal long-chain fatty acid absorption in rats. We administered [14C]oleic acid and oleyl alcohol as lipid emulsion intraduodenally in unanesthetized lymph-cannulated rats and measured the lymphatic output of oleic acid. Second, we orally administered lipid emulsion with a stomach tube and measured the luminal and mucosal oleic acid residues. Furthermore, rats were fed oleyl alcohol as a dietary component for 20 days, and fecal lipid and the weight of adipose tissues were measured. In lymph-cannulated rats, triglyceride and [14C]oleic acid output in the lymph were significantly lower in the presence of oleyl alcohol when compared with the absence of oleyl alcohol in a dose-dependent manner. The radioactivity remaining in the intestinal lumen was more strongly detected in rats that had been orally administered oleyl alcohol than in the controls. The feces of rats fed an oleyl-alcohol-added diet contained much higher amounts of lipids, and the weights of their adipose tissues were significantly lower than in the control group. These results suggest that oleyl alcohol inhibits the rat gastrointestinal absorption of long-chain fatty acids in vivo.

Mechanism of thiyl radical-catalyzed isomerization of unsaturated fatty acid residues in homogeneous solution and in liposomes

NMR spectroscopy and gas chromatography were used on methanolic solutions of fatty acid methyl esters and on small bilayer liposomes to study the radical-induced denaturation of the fatty acid residues from the natural cis-configuration into trans-isomers. To analyze the mechanism of the thiyl radical-catalyzed lipid isomerization, we compared the effects of thiols on oleic and linoleic fatty acid residues using pulse radiolysis, γ-radiolysis and chemolysis (AAPH) to generate thiyl radicals. The isomerization step takes place within the adduct of the thiyl radical to an olefinic group of unsaturated fatty acids, but not within the pentadienyl radical. The stability of the adduct can be described by an equilibrium constant of (12±5) mol −1 dm 3. The isomerization rate depends on the structure of the thiol. However, the resulting isomeric equilibrium ( trans-fraction: 81%) does not depend on the structure of the thiyl radical or the organization of the lipids. Quantum chemical calculations were performed to estimate the barriers for rotation, the geometry and the enthalpy difference between cis- and trans-thiyl radical adducts.

Interactions between Modified Mica Surfaces in Triglyceride Media

Results obtained from surface force measurements using modified nonpolar mica surfaces immersed in triolein are presented. The force vs distance curves were determined for different water activities in the interaction medium. Two oscillations with a periodicity of 20 Å were observed in the force curve measured across anhydrous triolein. The force barriers appear at separations of 45−40 and 20−30 Å. It is suggested that triolein has no clear preferential orientation of the oleic acid chains outside a nonpolar surface. This is different from outside a polar mica surface where triolein adopts conformations with the three oleic acid residues directed toward the bulk. At high water contents the triolein molecules outside nonpolar surfaces suddenly change their orientation when a high compressive force is applied. The forces acting between mica surfaces were measured in triolein solutions containing phospholipids at different water activities. It was shown that the phospholipid self-assembled onto the mica surfaces and rendered them nonpolar. The forces between such surfaces in anhydrous triolein are similar to those observed between mica hydrophobized using the Langmuir−Blodgett technique. In addition, at high water activities a weak long-range repulsive force was observed. This force was interpreted as being due to weakly adsorbed phospholipid aggregates. We discuss the implications of the results for the stability and physical properties of colloidal particle dispersions in nonpolar media. Adsorption isotherms for the phospholipid from refined vegetable oil at a low water activity on mica and sucrose crystals are presented. They show that the phospholipid adsorbs in a monolayer on mica. On sucrose more than monolayer coverage is observed, which we interpret in terms of a phase separation of phospholipid into crevices and cracks.

Lipase-catalyzed acidolysis of butterfat with oleic acid: characterization of process and product

The modification of anhydrous butterfat via interesterification reactions with oleic acid catalyzed by a lipase from Mucor circinelloides immobilized by adsorption onto hydrophobic hollow fibers is described. A reasonable degree of incorporation of free (externally added) oleic acid into the triacylglycerols of butterfat has been achieved while short-chain fatty acid residues remained virtually unaffected. Total saturated triacylglycerols decreased by 27%, and triacylglycerols with 32–44 acyl carbons (which contained two or three lauric, myristic, or palmitic acid residues) decreased by 33%. Total monoene and polyene triacylglycerols increased by 21% and 17%, respectively. The triacylglycerols (TAG) of interesterified butterfat had approximately 27% more oleic acid residues and approximately 8% less lauric, 6% less myristic, and 6% less palmitic acid residues than those of the original butterfat; the fraction of low-melting TAG peak increased by 19% whereas that of high-melting TAG decreased by 83%. Although a certain degree of butterfat hydrolysis was observed, enzymatic acidolysis was technically feasible and able to produce a modified butterfat with a stronger nutraceutical character.

Enzymatic interesterification of triolein and tristearin: Chemical structure and differential scanning calorimetric analysis of the products

AbstractThe structural composition and thermal properties of the products of enzymatic interesterification of triolein and tristearin were investigated. The biocatalyst for the reaction was an immobilized Candida antarctica lipase, SP435. Enzyme load of 10% (w/w reactants) produced 72% of desired total products. Oleoyl‐distearoyl triglycerides (SSO, OSS) had higher melting points than dioleoyl‐stearoyl triglycerides (OOS, SOO) because the sample contained larger amounts of stearic acid than oleic acid residues. SOS and OSO were hardly produced (0.2 to 1.2%), which indicates that SP435 acted as a nonspecific lipase when catalyzing the interesterification of triolein and tristearin. The maximal yield of OSS and SSO (46.9%) was achieved with a 1.2 mole ratio of triolein to tristearin. As the proportion of tristearin was increased, the production of SOO and OOS decreased, the melting profile of the interesterified triglycerides shifted toward higher melting forms, and the solid fat content increased, indicating formation of hard fats.

Inhibition of the human leukocyte endopeptidases elastase and cathepsin G and of porcine pancreatic elastase by N-oleoyl derivatives of heparin

N-oleoyl-heparin derivatives differing in their oleic acid and sulfate contents were synthesized and studied for their abilities to inhibit human leukocyte elastase (HLE), human leukocyte cathepsin G (CatG) and porcine pancreatic elastase (PPE) at pH 8.0, ionic strength 0.05 M and 37°. Heparin (Hep) as well as N-oleoyl-heparins behaved as tight-binding, hyperbolic noncompetitive inhibitors of HLE ( K iHep = 75 pM) and CatG ( K i Hep < 25 pM). The main driving force for the interaction between enzymes and glycosaminoglycans was electrostatic in nature. Under the condition [enzyme] ⪢ K i , the stoichiometries of the interaction with Hep were 1:2 (Hep:HLE) and 1:4 (Hep:CatG). Coupling one oleic acid residue to three disaccharide units of partially N-desulfated Hep, Ol 1:3 Hep, lowered HLE inhibition ( K i = 0.3 nM) and the stoichiometry of binding was reduced to 1:1. Re-N-sulfation of a similar derivative, OI 1:5 Hep(SO 4), containing one fatty acid residue for five disaccharide units, led to a substance with similar HLE inhibitory characteristics as Hep ( K i = 92 pM) and stoichiometry 1:2. 01 1:5Hep(SO 4) was also a more efficient inhibitor of CatG ( K i < 33 pM) than O1 1:3Hep ( K i = 9.5 nM). The residual activities of N-oleoyl-Hep complexes with CatG were much lower than the corresponding activities in the presence of Hep. While oleate and Hep could not inhibit PPE, N-oleoyl-Hep, independently of fatty acid substitution and sulfate content, could inhibit this enzyme with K i , ⋍ 60 nM and low residual activity. The efficient endopeptidase inhibitory characteristics of N-oleoyl-Hep derivatives, together with their non-anticoagulant properties and their capacity to interact with elastin, may be therapeutically useful in connective tissue degenerative diseases.

Proliferation-stimulating activity of detergents having oleic acid residues in serum-free culture of mammalian cells.

Proliferation-stimulating activity of detergents having oleic acid residues in serum-free culture of mammalian cells.

Comparative lipid analysis of purified plasma membranes and shed extracellular membrane vesicles from normal murine thymocytes and leukemic GRSL cells

The lipid fluidity in purified plasma membranes (PM) of murine leukemic GRSL cells, as measured by fluorescence polarization, is much higher than in PM of normal thymocytes. This was found to be due to relatively low contents of cholesterol and sphingomyelin and a high amount of unsaturated fatty acyl chains, especially linoleic acid, in the phospholipids. PM from GRSL cells contain markedly more phosphatidylethanolamine than those from thymocytes. For both GRSL cells and thymocytes the detailed lipid composition of isolated PM was compared with that of the corresponding shed extracellular membranes (ECM), which were isolated from the ascites fluid and from thymus cell suspensions, respectively. The somewhat decreased lipid fluidity of thymocyte ECM as compared to their PM, can be ascribed to the increased cholesterol/phospholipid molar ratio (0.88 vs. 0.74). No other major differences were found between the lipid composition of these membranes. In contrast, significant differences were found between PM and ECM from GRSL cells. In this system a much lower lipid fluidity of the shed ECM was found, due to the much increased cholesterol/phospholipid molar ratio (3.5-fold) and sphingomyelin (9-fold) content, as compared to the PM. Further, the ECM contain relatively more lysophosphatidylethanolamine and less phosphatidylcholine and -inositol. ECM contain a higher amount of polyunsaturated fatty acids, especially in the phosphatidylethanolamine and lysophosphatidylethanolamine classes. On the other hand, the fatty acids of phosphatidylcholine and lysophosphatidylcholine are more saturated than in PM. In particular, ECM of GRSL cells contain less oleic and linoleic acid residues and more arachidonic acid and 22:polyunsaturated fatty acid residues than PM. The possible relevance of these differences with respect to the mechanism of shedding of vesicles from the cell surface, is discussed.

The distribution of molecular classes of phosphatidylglycerol in the membrane of Acholeplasma laidlawii

A double-label technique has been applied to study the distribution of different molecular classes of phosphatidylglycerol in the membrane of Acholeplasma laidlawii. After growth on oleic acid, 16% of the total phosphatidylglycerol contains two oleic acid residues and 84% contains one oleic acid and one saturated fatty acid. The dioleoyl phosphatidylglycerol is present in equal amounts in the outer and the inner layer of the membrane. Phosphatidylglycerol which is associated with membrane proteins consists exclusively of the class containing only one oleic acid.