Chemistry of C-2 Glyceryl Radicals:  Indications for a New Mechanism of Lipid Damage

Müller, S.; Batra, Rohit; Senn, Martin; Giese, Bernd; Kisel, Micail; Шадыро, О. И.

doi:10.1021/ja9641416

Cited by 70 publications

(49 citation statements)

References 20 publications

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“…Properties of radical intermediates generated from lipids were studied using various selective and non-selective methods [12]. It has been established [12] that carbon-centered α-hydroxyl-containing radicals formed from lipids are primarily responsible for the fragmentation process. Taking into account the experimentally established facts mentioned above, the DA/Fe 2+ system, which produces • OH radicals according to Fig.…”

Section: Figmentioning

confidence: 99%

“…Previously, we have shown that lipids with structures containing a free hydroxyl group in β-position to the phosphoester, amide or glycoside bonds undergo, along with peroxidation, a free-radical fragmentation process [1,11,12,[14][15][16]. This process occurs in the polar part of the lipid and leads to lipid destruction due to rupture of phosphoester, amide or glycoside bonds.…”

Section: Introductionmentioning

confidence: 99%

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Dopamine and iron mediated fragmentation of galactocerebroside and cardiolipin in micelles

et al. 2007

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Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and thin-layer chromatography (TLC) have been used to study dopamine and iron mediated freeradical transformation of lipids in their hydrophilic parts. It has been shown that the action of the dopamine/Fe 2+ system on galactocerebroside or cardiolipin, which are the components of mixed micelles, results in formation of ceramide or phosphatidic acid and phosphatidylhydroxyacetone, respectively. These data, when combined with results obtained using the ascorbate/Fe 2+ /H 2 O 2 oxidizing system with the same substrates, demonstrate that the formation of these products proceeds via an OH-radical induced fragmentation taking place in polar moiety of the starting lipids.

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Section: Figmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dopamine and iron mediated fragmentation of galactocerebroside and cardiolipin in micelles

et al. 2007

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“…The transverse-field muon spin rotation (TF-MuSR) method 5 is highly specific for the detection of free radicals which are labelled by a muon, and so radicals formed by addition [Eqn (2)] are the only contributors to the TF-MuSR spectrum; those arising from abstraction are invisible to the muon, which is lost as (non-radical) muonated dihydrogen [Eqn (1)]. …”

Section: Muonium Radiolabelling Techniquementioning

confidence: 99%

“…1 From a recent chemical study, however, has emerged the view that abstraction from the glyceryl unit of a phospholipid, leading to a C-2 glyceryl radical (I), might be of significance. 2 In a lyolipid (II), the resulting glyceryl radical (III) has the structural feature of a hydroxyl group substituting the radical centre, along with two ester moieties: model systems show that the rapid elimination of an acid occurs, leaving an enolate radical (IV); in contrast, acyloxy derivatives (V) are stable to elimination. The significance of lyolipids II is that they are formed at an accelerated rate from normal lipids which have been partially oxidized, and their further oxidation, to radicals of type III, might make a significant contribution to the overall lipid damage, since conversion of III to IV truncates the reconversion, overall, of II to normal lipid.…”

Section: Introductionmentioning

confidence: 99%

Radiolabelling studies of free radical reactions using muonium (the second hydrogen radioisotope): evidence of a direct antioxidant role for vitamin k in repair of oxidative damage to lipids

et al. 2000

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Following the recent suggestion that oxidative damage to lipids might involve the formation of C‐2 glyceryl radicals, in addition to main‐chain allylic radicals, which are generally thought important, we studied the kinetics of potential ‘repair’ reactions by vitamin E and vitamin K1 (which are lipophilic and tend to locate in cell membranes) with 1,1,2‐trimethylallyl and 1‐acetoxyprop‐2‐yl radicals as models of, respectively, main‐chain and glyceryl‐type radicals. The second‐order rate constants for the reaction between trimethylallyl radicals and vitamin E and vitamin K1 are 9.38 × 106 and 3.54 × 108 l mol−1 s−1 and those between 1‐acetoxyprop‐2‐yl radicals and vitamin E and vitamin K1 are 1.76 × 108 and 2.03 × 106 l mol−1 s−1, respectively. The results suggest that direct scavenging of glyceryl radicals by vitamin E should be an efficient process, and of main‐chain allylic radicals fairly so. Additionally, it appears that vitamin K1 can act directly as a ‘radical repair agent,’ given its relatively high reactivity with allylic radicals (four times faster than with vitamin E), so prior reduction to the quinol form may be unnecessary. Copyright © 2000 John Wiley & Sons, Ltd.

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“…The antioxidant activity of flavonols, as well as a number of other flavonoids, is responsible for their useful therapeutic properties. Because of this, it is of considerable interest to study the properties of this class of compounds.Previously [5][6][7][8], it was found that biologically important molecules exposed to γ -radiation and other initiators of free-radical processes can be damaged not only by oxidation but also as a result of fragmentation. In the latter process, the step of degradation of α -hydroxyl-containing radicals plays a key role.…”

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Effect of flavonols on radiation-induced reactions with the participation of α-hydroxyl-containing organic radicals

Grintsevich

Шадыро

2005

High Energy Chem

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1 Flavonols, which are plant polyphenols, are widely used for the regulation of free-radical oxidation processes in biological systems [1][2][3][4]. The antioxidant activity of flavonols, as well as a number of other flavonoids, is responsible for their useful therapeutic properties. Because of this, it is of considerable interest to study the properties of this class of compounds.Previously [5][6][7][8], it was found that biologically important molecules exposed to γ -radiation and other initiators of free-radical processes can be damaged not only by oxidation but also as a result of fragmentation. In the latter process, the step of degradation of α -hydroxyl-containing radicals plays a key role. It was also found [9, 10] that carbonyl-containing compounds and quinones affect free-radical processes that involve α -hydroxyl-containing carbon-centered organic radicals. As regards flavonoids, only a few publications [11][12][13][14] have been devoted to their reactivity toward carbon-centered radicals.In this paper, we report data that allow us to judge the probabilities and reaction pathways of flavonols and structurally related model compounds with organic radicals formed in the radiolysis of ethanol and aqueous ethylene glycol and 2-methoxyethanol solutions. EXPERIMENTALThe figure summarizes the structural formulas of compounds used in this study. Commercial quercetin (more than 95% purity), rutin (more than 95% purity), morin (more than 95% purity), maltol (more than 98% purity), and kojic acid (more than 98% purity) from Aldrich were used without additional purification. Ethanol (96 vol %) was purified using Wolfen Zeosorb LA zeolite and distilled using a 3-m rectification column. 1 Ethylene glycol and 2-methoxyethanol were purified by double distillation. The purity of the substances was monitored by chromatography.Before dissolving samples, ethanol was sparged with high-purity argon (99.9%) for 50 min. All of the subsequent procedures up to sealing ampules with solutions were performed in an argon atmosphere.Ethylene glycol and 2-methoxyethanol solutions at a concentration of 3 mol/l were prepared with twicedistilled water, fresh solutions being used for each particular set of experiments. Required concentrations of additives in the resulting solutions were obtained by introducing weighed portions of test substances into the solutions. Oxygen was removed by five freezingpumping-thawing cycles. Next, the ampules were sealed under vacuum.The γ -radiation of 137 Cs was used as an initiator of free-radical processes in model systems. Irradiation was performed in sealed ampules (inner diameter, 6 mm; height, 40 mm; sample volume, 0.7 ml). The dose rate was 0.31 ± 0.01 Gy/s; the absorbed dose range 0.2-3.5 kGy was used.All of the data given were obtained by averaging the results of no less than three sets of experiments. The radiation-chemical yields of formation of substances were determined from the dose dependence of the buildup of these substances.The concentrations of acetaldehyde, 2,3-butanediol, and methano...

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Chemistry of C-2 Glyceryl Radicals: Indications for a New Mechanism of Lipid Damage

Cited by 70 publications

References 20 publications

Dopamine and iron mediated fragmentation of galactocerebroside and cardiolipin in micelles

Dopamine and iron mediated fragmentation of galactocerebroside and cardiolipin in micelles

Radiolabelling studies of free radical reactions using muonium (the second hydrogen radioisotope): evidence of a direct antioxidant role for vitamin k in repair of oxidative damage to lipids

Effect of flavonols on radiation-induced reactions with the participation of α-hydroxyl-containing organic radicals

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