Autoxidation of micelles and model membranes. Quantitative kinetic measurements can be made by using either water-soluble or lipid-soluble initiators with water-soluble or lipid-soluble chain-breaking antioxidants

The aims of the present study are to establish an appropriate system for assessing the oxidizability of cholesterol (CH) in phospholipid (PL) bilayers, and to explore the effect of ethanolamine plasmalogens on the oxidizability of CH with the system, through comparing with those of choline plasmalogens, phosphatidylethanolamine, and antioxidant ␣ -tocopherol (Toc). Investigation of the effects of oxidants, vesicle lamellar forms, saturation level, and constituent ratio of PLs in vesicles on CH oxidation revealed the suitability of a system comprising unilamellar vesicles and the watersoluble radical initiator 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH). As CH oxidation in the system was found to follow the rate law for autoxidation without significant interference from oxidizable PLs, the oxidizability of CH in PL bilayers could be experimentally determined from the equation

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“…e, is taken as 0.64 from the average value measured 15 times by the induction period method (34) with a watersoluble antioxidant, Trolox (35).…”

Section: Oxidation System For Assessing the Oxidizability Of Ch In Plmentioning

confidence: 99%

Ethanolamine plasmalogens prevent the oxidation of cholesterol by reducing the oxidizability of cholesterol in phospholipid bilayers

Maeba

Ueta

2003

Journal of Lipid Research

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“…This finding is consistent with what other workers have reported, in which they observed that the interaction of flavonoids with a model membrane, including their incorporation rate into cells and their orientation in a biomembrane, affected their AA or other pharmacological effects. [20][21][22][23][24] AA of Tea Extract The study of catechins is particularly important for the understanding of the antioxidant property of tea. In this paper, the AA of tea extract (mainly containing polyphenols) was tested.…”

Section: In Our Experiments There Were Various Differences Between Tmentioning

confidence: 99%

Relationship of Electrochemical Oxidation of Catechins on Their Antioxidant Activity in Microsomal Lipid Peroxidation.

Yang

Kotani

Arai

et al. 2001

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…We are quantitative kinetic Illethods the cage where they are formed; therefore the ac,,al Ri must be autoxidation of biological molecules in microenvironments measured, for example, by the inhibitor method (9) using a such as bila~ers and micelles (5)(6)(7)(8) Autoxidation in these phenolic antioxidant such as a-tocopherol (&-T) known to Vap ' Ystems is a free-radica1 process which appears two peroryl radicals (lo), so that Ri is given by eq.…”

Section: Introduction D[021 Kpmentioning

confidence: 99%

Quantitative studies of the autoxidation of linoleate monomers sequestered in phosphatidylcholine bilayers. Absolute rate constants in bilayers

Barclay¹,

Locke²,

MacNeil³

et al. 1985

Can. J. Chem.

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Chem. 63, 2633 (1985).The kinetics of autoxidation of linoleic acid in dimyristoylphosphatidylcholine (DMPC) bilayers were studied at 30°C and pH 7 under 760 Torr 02. Reactions were initiated using either the lipid-soluble di-tert-butylhyponitrite (DBHN) or watersoluble azobis(2-amidinopropane) . HCI (ABAP). Rates of chain initiation, R i , were measured with a lipid-soluble antioxidant, a-tocopherol, or a water-soluble one, 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxyate (Trolox). The slightly higher oxidizability pbtained (kp/2k$ = 2.76 x lo-' M-i s-4 compared to methyl linoleate in chlombenzene (kp/2k$ = 2.18 x ]0-2 M-i -2 s 3 is attributed to a moderate polar solvent effect on ionized linoleate near the bilayer surface. A low initiator efficiency, e = 0.0895 for DBHN in DMPC, is attributed to the cage effect in the bilayer of high microviscosity. Similar autoxidation experiments on methyl linoleate in DMPC bilayers gave a lower oxidizability (kp/2k) = 1.79 x lo-' M-i s-i), indicating that the ester is sequestered deeper in the hydrophobic region of DMPC than is ionized linoleate. Some absolute rate constants are determined using the rotating sector technique for linoleic acid in 0.50 M SDS micelles, and egg lecithin and dilinoleoylphosphatidylcholine (DLPC) bilayers. A hundredfold decrease in the termination rate constant, 2k,, for DLPC bilayer compared to homogeneous solution is attributed to chain termination in a bilayer region of high polarity. A concomitant reduction (up to tenfold) in the propagation rate constant, k,, is attributed to diffusion of polar peroxyl radicals away from the oxidizable region of the bilayer.LAWRENCE ROSS COATES BARCLAY, STEVEN JEFFREY LOCKE, JOSEPH MARK MACNEIL et JOANN VANKESSEL. Can. J. Chem. 63, 2633 (1985).Opt5rant h 30°C, i un pH de 7 et sous une pression de 760 Torr d'02, on a ttudiC la cinktique de I'auto-oxydation de I'acide IinolCique dans des couches doubles de dimyristoylphosphatidylcholine (DMPC). On a initie les reactions i I'aide soit de I'hyponitrite du di-tert-butyle (HNDB) qui est soluble dans les lipides soit le chlorhydrate de I'azo bis(amidin0-2 propane) (ABAP) qui est soluble dans I'eau. On a mesure les vitesses d'initiation de chaines, Ri, en presence d'un antioxydant soluble dans I'eau, I'a-tocophCrol, ainsi que d'un antioxydant soluble days I'eau, I'hydroxy-q tt5pamethyl-2,5,7,8 chromanecarboxylate-2 (Trolox). L'oxyd,abifite est 1Cgkrement supt5rieure (k,/2k? = 2,76 x lo-' M-7 s-3 h celle du linoleate de mCthyle (kp/2k,3 = 2,18 x lo-' M-i s-3; on attribue ce resultat h une influence modCree du solvant polaire sur le linoltate ionis6 prks de la surface i couche double. On attribue la faible efficacitk comme initiateur, e = 0,0895, du HNDB dans le DMPC i un effet de cage dans la double couche qui aurait une microviscositC ClevCe. Des experiences semblables d'a~to~oxydation sur le linolkate de mCthyle dans des doubles couches de DMPC donnent lieu i des oxydabilites plus faibles (kp/2k,5 = 1,79 x M-f s-$; ce rksultat indiquerait que I'ester est plus sequ...

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Autoxidation of micelles and model membranes. Quantitative kinetic measurements can be made by using either water-soluble or lipid-soluble initiators with water-soluble or lipid-soluble chain-breaking antioxidants

Cited by 223 publications

References 4 publications

Ethanolamine plasmalogens prevent the oxidation of cholesterol by reducing the oxidizability of cholesterol in phospholipid bilayers

Ethanolamine plasmalogens prevent the oxidation of cholesterol by reducing the oxidizability of cholesterol in phospholipid bilayers

Relationship of Electrochemical Oxidation of Catechins on Their Antioxidant Activity in Microsomal Lipid Peroxidation.

Quantitative studies of the autoxidation of linoleate monomers sequestered in phosphatidylcholine bilayers. Absolute rate constants in bilayers

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