The autoxidation of unsaturated lipids in micelles. Synergism of inhibitors vitamins C and E

1983 ◽  
Vol 61 (6) ◽  
pp. 1288-1290 ◽  
Author(s):  
Lawrence Ross Coates Barclay ◽  
Steven Jeffrey Locke ◽  
Joseph Mark MacNeil
Keyword(s):  
Linoleic Acid ◽  
Methyl Linoleate ◽  
Sodium Dodecyl ◽  
Square Root ◽  
Micellar Phase ◽  
Chain Initiation ◽  
Unsaturated Lipids ◽  
Sds Micelles ◽  
Initiator Efficiency ◽  
Kinetics Of

The kinetics of thermally (30 °C) initiated autoxidations of unsaturated lipids, linoleic acid, and methyl linoleate are studied in 0.50 M sodium dodecyl sulfate (SDS) micelles. The rate of chain initiation, R1, was controlled by using known amounts of the thermal initiator, di-tert-butylhyponitrite (DBHN). The initiator efficiency, e, determined by the induction period method with x-tocopherol, was 0.30 for linoleic acid and varied (0.30 to 0.36) for methyl linoleate autoxiation as the concentration of the ester increased. The rate of autoxidation of linoleic acid follows the classical rate law since it is proportional to the substrate concentration and to the square root of chain initiation. The oxidizability of linoleic acid measured in micelles is 4.09 × 10−2 M−1/2 s−1/2. The oxidizability of methyl linoleate varied from 2.37 × 10−2 to 6.92 × 10−2 M−1/2 s−1/2 as the amount of solubilized ester increased. The latter results are indicative of pooling of the ester in the micellar phase. Additions of aqueous solutions of ascorbic acid to α-tocopherol-inhibited micellar autoxidations result in very significant extensions of the efficient inhibition period compared to that obtained with α-tocopherol alone. The mechanism of this synergism is briefly discussed.

Article

1998 ◽  
Vol 76 (2) ◽  
pp. 171-182 ◽  
Author(s):  
Fengde Xi ◽  
L Ross Barclay
Keyword(s):  
Methyl Linoleate ◽  
Antioxidant Activities ◽  
Lignin Content ◽  
Synergistic Effects ◽  
Sodium Dodecyl ◽  
Ascorbyl Palmitate ◽  
Semiquinone Radical ◽  
Semiquinone Radicals ◽  
Sds Micelles

The antioxidant activities, kinh, of catechol, 1, 4-tert-butylcatechol, 2, and 3,5-di-tert-butylcatechol (DTBC), 3, determined by the inhibited oxygen-uptake method during peroxidation of styrene initiated by AIBN are 55.0 x 104, 88.4 x 104, and 149 x 104 M-1s-1, respectively, and the stoichiometric factors (n) were 2.1-2.3. A decrease by 50-fold in kinh for 3 and a drop of 1.1-1.4 in n observed during inhibited peroxidation of methyl linoleate in aqueous sodium dodecyl sulfate (SDS) initiated by di-tert-butylhyponitrile (DBHN) is attributed to hydrogen bonding by water on the antioxidant and on the intermediate di-tert-butylsemiquinone radical, 5, formed in the inhibition step. Combinations of ascorbyl palmitate with 3 exhibited cooperative (not synergistic) antioxidant effects during inhibited peroxidation of styrene in solution. Combinations of ascorbic acid with 3 exhibited synergistic effects during inhibited peroxidation of methyl linoleate initiated by DBHN in SDS micelles. A profile of the effect of concentration of ascorbate on this synergism indicates a mole of 3 is regenerated per mole of ascorbate. The thiols, homocysteine, and polyethylene glycol thiol (polythiol) also exhibited synergistic effects with DTBC in this inhibition. Either ascorbate or polythiol rapidly reduces di-tert-butyl-ortho-quinone (DTBQ), 4, to 3 in methanol or in SDS micelles, and the combination of 3 + ascorbate acted as an efficient inhibitor in this medium. The esr studies indicate the semiquinone radical, 5, produced photochemically from 3 or spontaneously from 3 + 4 in solution, to be very persistent at room temperature. A pathway, mediated by 5, is proposed to account for the cooperative and synergistic effects observed and for the additional combination effect discovered when the three inhibitors: 3, ascorbate, and a thiol are used in the SDS medium. Combinations of such antioxidants are expected to be useful for inhibition of yellowing of pulps and paper with high lignin content, and to be significant in the in vivo reductions of ortho-quinones and semiquinone radicals formed during oxidations of various biomolecules.Key words: catechols, ascorbate, thiols, radicals, antioxidants.

Autoxidation in micelles. Synergism of vitamin C with lipid-soluble vitamin E and water-soluble Trolox

1985 ◽  
Vol 63 (2) ◽  
pp. 366-374 ◽  
Author(s):  
Lawrence Ross. Coates. Barclay ◽  
Steven Jeffrey. Locke ◽  
Joseph Mark MacNeil
Keyword(s):  
Linoleic Acid ◽  
Sodium Dodecyl ◽  
Homogeneous Solution ◽  
Kinetic Studies ◽  
Water Soluble ◽  
Interfacial Region ◽  
Induction Periods ◽  
Quantitative Studies ◽  
Sds Micelles ◽  
Soluble C

A study was made of the effect of the inhibitors ascorbic acid (C), α-tocopherol (E), and 6-hydroxy-2,5,7,8-tetramethyl-chroman-2-carboxylate (Trolox, T) on the autoxidation of linoleic acid in 0.50 M sodium dodecyl sulfate (SDS) micelles at pH 7.0 in phosphate buffer. Reactions were thermally initiated at 30 °C in the SDS micelles by a micelle-soluble initiator, di-tert-butylhyponitrite (DBHN). Although water-soluble C alone is an inefficient inhibitor, when combined with micelle-soluble E, it acts synergistically with the latter to extend the efficient antioxidant action of E beyond the sum of the induction periods of C and E acting separately. Similarly C acts synergistically with the water-soluble antioxidant, T. Quantitative studies of these effects under controlled rates of initiation (Ri,) reveal that C functions to regenerate a mole of E (or T) per mole of C used. Kinetic studies show that the rate of autoxidation is first order in micellar linoleic acid and one-half order in micellar DBHN concentrations. Therefore, the classical rate law, −dO2/dt = kp[R—H] (Ri)1/2/(2k1)1/2 is followed. The higher oxidizability (kp/2kt1/2 = 4.48 × 10−2 M−1/2 s−1/2) of linoleate in micelles compared to that in homogeneous solution in chlorobenzene (kp/2kt1/2 = 2.30 × 10−2 M−1/2 s−1/2) is interpreted in terms of the effect of the polar interfacial region of the micelles on a dipolar transition state, R—OŌ: H•R, of the propagation reaction.

scholarly journals Incorporation of Ag Nanoparticles Into Micelles. Stability Studies of Self-Organized Nanoparticlesmicelles Structures

2016 ◽  
Vol 39 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Przemysław Siejak ◽  
Krzysztof Polewski
Keyword(s):  
Ag Nanoparticles ◽  
Biological Membrane ◽  
Sodium Dodecyl ◽  
Ammonium Bromide ◽  
Physical Parameters ◽  
Aqueous Environment ◽  
Self Organized ◽  
Sds Micelles ◽  
Triton X ◽  
Kinetics Of

Abstract In this paper we present the results of measured physical parameters of self-organized structures consisting of hydrophobic functionalized silver nanoparticles and amphiphilic molecules capable of micelles formation. Those systems may be considered as simple models for transfer of nanoparticles through the biological membrane. Three different surfactants were used: negatively charged sodium dodecyl sulphite, SDS, neutral Triton X-100 and positively charged tetredodecyltrimethyl ammonium bromide, TTABr. We have found that hydrophobic functionalized Ag nanoparticles are encapsulated in neutral Triton X-100 micelles with a diameter of 10 nm without significant change in the size of the micelles. The efficiency of encapsulation of Ag by SDS micelles is lower compared to Triron X-100 and no incorporation of Ag nanoparticles into TTABr occurs. Obtained results indicate that in aqueous environment ionic properties of molecules creating micelles and concentration ratios between components determine the efficiency and kinetics of two competitive processes association or aggregation of nanoparticles and encapsulation of Ag nanoparticles within micelles.

The Kinetics of Methyl Methacrylate Miniemulsion Polymerization Characterized through a Fluorescence Method

2012 ◽  
Vol 178-181 ◽  
pp. 609-612
Author(s):  
Hai Ke Feng ◽  
Hua Yu Qiu ◽  
Li Yuan Ding ◽  
Cun Jin Xu
Keyword(s):  
Methyl Methacrylate ◽  
Anionic Surfactant ◽  
Sodium Dodecyl Sulphate ◽  
Sodium Dodecyl ◽  
Miniemulsion Polymerization ◽  
Time Measurement ◽  
Fluorescence Method ◽  
Real Time Measurement ◽  
Measurement Results ◽  
Kinetics Of

In this paper, we followed the kinetics of methyl methacrylate (MMA) through a novel fluorescence method. The real-time measurement results show that in the regime of very low monomer contents, such as a solution containing 0.1 wt% of MMA with respect to water and with the anionic surfactant of sodium dodecyl sulphate (SDS), the kinetic of the miniemulsion could be followed by this embed fluorescence method. The processes of changing from emulsion to miniemulsion with different amount of surfactant and cosurfactant also have been monitored.

scholarly journals Fibronectin–collagen binding and requirement during cellular adhesion

1980 ◽  
Vol 186 (2) ◽  
pp. 551-559 ◽  
Author(s):  
Leslie I. Gold ◽  
Edward Pearlstein
Keyword(s):  
Chick Embryo ◽  
Human Plasma ◽  
Hydrophobic Interactions ◽  
Human Fibroblasts ◽  
Sodium Dodecyl ◽  
Cellular Adhesion ◽  
Adhesion Assay ◽  
Human Umbilical Cord ◽  
Ionic Detergents ◽  
Kinetics Of

Fibronectin isolated from human plasma and from the extracellular matrices of cell monolayers mediates the attachment in vitro and spreading of trypsin-treated cells on a collagen substratum. Fibronectin-dependent kinetics of cellular attachment to collagen were studied for several adherent cell types. It was shown that trypsin-treated human umbilical-cord cells, mouse sarcoma CMT81 cells, endothelial cells, and human fibroblasts from a patient with Glanzmann's disease were completely dependent on fibronectin for their attachment to collagen, whereas guinea-pig and monkey smooth-muscle cells and chick-embryo secondary fibroblasts displayed varying degrees of dependence on fibronectin for their attachment. Radiolabelled human plasma fibronectin possessed similar affinity for collagen types I, II and III from a variety of sources. The fibronectin bound equally well to the collagens with or without prior urea treatment. However, in the fibronectin-mediated adhesion assay using PyBHK fibroblasts, a greater number of cells adhered and more spreading was observed on urea-treated collagen. Fibronectin extracted from the extracellular matrix of chick-embryo fibroblasts and that purified from human plasma demonstrated very similar kinetics of complexing to collagencoated tissue-culture dishes. Fibronectin from both sources bound to collagen in the presence of 0.05–4.0m-NaCl and over the pH range 2.6–10.6. The binding was inhibited when fibronectin was incubated with 40–80% ethylene glycol, the ionic detergents sodium dodecyl sulphate and deoxycholate, and the non-ionic detergents Nonidet P-40, Tween 80 and Triton X-100, all at a concentration of 0.1%. From these results we proposed that fibronectin–collagen complexing is mainly attributable to hydrophobic interactions.

Quantitative Determination of Linoleic Acid in Infant Formulas by Gas Chromatography

1987 ◽  
Vol 70 (4) ◽  
pp. 702-705
Author(s):  
Theresa W Lee
Keyword(s):  
Gas Chromatography ◽  
Linoleic Acid ◽  
Methyl Linoleate ◽  
Quantitative Determination ◽  
Methyl Esters ◽  
Infant Formulas ◽  
Methyl Heptadecanoate ◽  
Glass Column ◽  
Peak Areas

Abstract A method has been developed for the quantitative determination of linoleic acid in infant formulas by gas chromatography (GC). A known amount of triheptadecanoin was spiked into the sample. Total lipid was extracted from the product by an ethyl ether-petroleum etherethanol system in a Mojonnier flask. The sample was saponified by methanolic KOH after the solvents were evaporated. Methyl esters of the fatty acids were prepared by boron trifluoride (BF3) in methanol and analyzed by gas chromatography. A glass column packed with 10% SP-2340 (75% cyanopropyl silicone) was used to separate and identify the methyl linoleate and the methyl heptadecanoate. The quantity of methyl linoleate was calculated by comparing the integrated peak areas of these 2 fatty acid methyl esters. This method was satisfactory for both milk protein-based and soy protein-based matrixes. The results obtained by this method are comparable to those obtained by the AOAC spectrophotometric method 28.082- 28.085.

Mobility of DR1 Molecules Embedded in Nanostructured PMMA Films

2009 ◽  
Vol 5 ◽  
pp. 135-142
Author(s):  
Jorge A. García-Macedo ◽  
A. Franco ◽  
Guadalupe Valverde-Aguilar ◽  
M.A. Ríos-Enríquez
Keyword(s):  
Second Harmonic ◽  
Sodium Dodecyl ◽  
Orientation Distribution ◽  
Decay Rates ◽  
Ammonium Bromide ◽  
X Ray Diffraction ◽  
Poling Field ◽  
Different Temperatures ◽  
Cetyl Trimethyl Ammonium ◽  
Kinetics Of

The kinetics of the orientation of Disperse Red 1 (DR1) molecules embedded in nanostructured Polymethylmetacrylate (PMMA) films was studied under the effect of an intense constant electric poling field. The changes in the orientation distribution of the DR1 molecules were followed by Second Harmonic Generation (SHG) measurements. The SHG signal was recorded as function of time at three different temperatures. We focused on both, the signal increases under the presence of the poling field and the signal decays without the poling field. The studied PMMA films were nanostructured by the incorporation of ionic surfactants as the Sodium Dodecyl Sulfate (SDS) and the Cetyl Trimethyl Ammonium Bromide (CTAB) during their preparation. The kinds of nanostructures obtained in the films were determined by means of X-ray diffraction (XRD) measurements. Substantial differences in signal intensity and in growth and decay rates between amorphous and nanostructured films were found.

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