Free Radical Production From the Ozonation of Simple Alkenes, Fatty Acid Emulsions and Phosphatidylcholine Liposomes

Church, Daniel F.; McAdams, Michelle; Pryor, William A.

doi:10.1016/b978-0-08-041749-3.50095-4

Cited by 7 publications

(9 citation statements)

References 13 publications

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“…Our data support this suggestion, since we find that rbc lysis caused by ozonized PC is not radical-mediated but rather is caused by an unknown synergistic reaction of aldehydes and hydrogen peroxide (30,56). However, we do find that a direct reaction of ozone with olefins leads to spin-trappable free radicals and that this process occurs not only in organic solvents but also in homogeneous aqueous solution, micelles, and liposomes (30,31); it is likely that these organic radicals are at least partially responsible for the lipid peroxidation commonly observed when unsaturated fatty acids or lipids are exposed to ozone (30,31).…”

Section: Mudd Et Al (supporting

confidence: 80%

“…The results described here indicate that ozonations of aqueous systems containing unsaturated fatty acids or their methyl or phosphatidylcholine esters produce approximately 1 mol of hydrogen peroxide and 2 mol of aldehydes per mole of ozone reacted and of alkene consumed. Under our reaction conditions we observe the formation of very little (about 5% or less) other peroxidic materials (30,31).…”

Section: Introductionmentioning

confidence: 71%

“…We recently suggested that the UFA in lung lining fluids, including mucus and surfactant, are a primary target for ozone (29)(30)(31). Surfactant in different animals contains lipids with from 15% to 40% unsaturated fatty acids (52) and to some degree resembles an aqueous emulsion of fatty acids and other materials (55).…”

Section: Introductionmentioning

confidence: 99%

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The ozonation of unsaturated fatty acids: aldehydes and hydrogen peroxide as products and possible mediators of ozone toxicity

Pryor

Das²,

Church³

1991

Chem. Res. Toxicol.

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189

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The products of the reactions of ozone with aqueous emulsions of unsaturated fatty acids and with liposomes made from phosphatidylcholine esters were characterized. Ozonolysis of emulsions of methyl oleate yields approximately 1 mol of hydrogen peroxide and 2 mol of aldehydes per mole of ozone used and fatty acid reacted. That is, the net equation that occurs is RCH = CHR' + O3 + H2O----RCHO + R'CHO + H2O2 . Ozonolysis of emulsions of oleic, linoleic, linolenic, and arachidonic acids gives 1 mol of hydrogen peroxide per mole of ozone used. Only very low yields (less than 5%) of reducible materials other than hydrogen peroxide are observed, suggesting that the yields of organic peroxidic materials, including Criegee ozonides and lipid hydroperoxides, are small. Ozonolysis of rat erythrocyte ghost membranes and rat bronchoalveolar lavage also gives significant yields (about 50%) of hydrogen peroxide based on the moles of ozone consumed. Reactions of ozone with bovine serum albumin, glutathione, and glucose do not produce hydrogen peroxide, implying that the hydrogen peroxide formed during the ozonation of biological materials arises almost exclusively from ozone/olefin reactions. Hydrogen peroxide and aldehydes are suggested to be important mediators of the modifications observed in both the lung and extrapulmonary tissues when ozone is inhaled.

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Section: Mudd Et Al (supporting

confidence: 80%

Section: Introductionmentioning

confidence: 71%

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The ozonation of unsaturated fatty acids: aldehydes and hydrogen peroxide as products and possible mediators of ozone toxicity

Pryor

Das²,

Church³

1991

Chem. Res. Toxicol.

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189

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“…The 1-hydroxy-l-alkyl hydroperoxide is an intermediate in the production of aldehydes and hydrogen peroxide, but it hydrolyzes to the aldehyde and hydrogen peroxide under conditions that model pulmonary exposures to low concentrations of ozone (32)(33)(34). In addition to carbonyl compounds and hydrogen peroxide, peroxidic compounds (1,22,35) and/or radicals (36)(37)(38)(39) also are produced.…”

Section: Introductionmentioning

confidence: 99%

Ozonation of methyl oleate in hexane, in a thin film, in SDS micelles, and in distearoylphosphatidylcholine liposomes: yields and properties of the Criegee ozonide

Pryor¹,

Wu²

1992

Chem. Res. Toxicol.

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We here explore the use of Criegee ozonides as markers of ozone damage to lipids in systems that model pulmonary surfactant, lung lining fluids, and/or pulmonary membranes. Ozonation of methyl oleate in hexane gives an 89% yield of the Criegee ozonide. The presence of water should reduce the yield of this ozonide, and as expected, small but significant yields of Criegee ozonides are formed when the ozonation of methyl oleate is carried out as a film over phosphate buffer, in aqueous micelles of sodium dodecyl sulfate (SDS), or in distearoyl-L-alpha-phosphatidylcholine (DSPC) liposomes spiked with methyl oleate. Analysis utilizes reversed-phase HPLC and 1H NMR. The total yield of ozonides in 0.02 M SDS micelles exposed to 26 ppm ozone for 3 h at pH 7.4 and 22 degrees C is 11%; 7.5% is the normal ozonide, methyl 5-octyl-1,2,4-trioxolane-3-octanoate (MOO2) (ca. 4.2% trans and ca. 3.3% cis), and 3.5% is accounted for by the two cross ozonides, 3,5-dioctyl-1,2,4-trioxolane (MOO1) and dimethyl 1,2,4-trioxolane-3,5-dioctanoate (MOO3). No significant difference of ozonide yields is observed for ozonations with 26 ppm and 1.2% (12,000 ppm) ozone. The conversion of methyl oleate increaes with increasing SDS concentration. Approximately comparable yields of ozonides also are found in the ozonation of methyl oleate in DSPC liposomes although yields are not quantified. The ozonides slowly hydrolyze at pH 7.4 and 37 degrees C with half-lives for trans-MOO2 and cis-MOO2 in 0.10 M SDS micelles of 23 and 6 days, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

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“…Unpublished model experiments demonstrate that other atmospheric processes form radicals that are detectable by spin trapping. It is known that ozone reacts with alkenes in solution to produce spin adducts that are detectable by spin trapping (46). When gaseous mixtures of ozone and propylene are allowed to react for various periods of time before the gas mixture passes into a solution of PBN, strong spin adduct spectra are observed.…”

Section: Polluted Airmentioning

confidence: 99%

Spin Trapping Organic Radicals

Church¹

1994

Anal. Chem.

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Free radicals play an important role in a number of toxicologically significant gas-phase environments, including smoke resulting from combustion, gases formed by pyrolytic processes, and polluted air. The reactivity associated with many radicals has led to considerable speculation about their association with the toxic effects of smoke or polluted air. Thus the development of methods for studying these species has been an important goal in many laboratories.Because reactive radicals in smoke or polluted air typically occur at low concentrations in complex matrices, techniques that are sensitive and selective are needed for their unambiguous detection, identification, and accurate quantitation. The requirement that they be radical-specific places fairly stringent limitations on the methods available for studying radicals in the gas phase. IR, UV-vis, and fluorescence spectroscopies have all been usedto study gas-phase radicals (i); however, it becomes increasingly difficult to apply these techniques as the composition of the gas-phase mixture becomes more complex.Electron paramagnetic resonance (EPR) spectroscopy appears to be well suited for the determination of low concentrations of free radicals in complex gaseous media. EPR spectroscopy is highly selective; it detects only species that are paramagnetic (radicals, diradi-

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Free Radical Production From the Ozonation of Simple Alkenes, Fatty Acid Emulsions and Phosphatidylcholine Liposomes

Cited by 7 publications

References 13 publications

The ozonation of unsaturated fatty acids: aldehydes and hydrogen peroxide as products and possible mediators of ozone toxicity

The ozonation of unsaturated fatty acids: aldehydes and hydrogen peroxide as products and possible mediators of ozone toxicity

Ozonation of methyl oleate in hexane, in a thin film, in SDS micelles, and in distearoylphosphatidylcholine liposomes: yields and properties of the Criegee ozonide

Spin Trapping Organic Radicals

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