Oxidative stress effect on the integrity of lipid bilayers is modulated by cholesterol level of bilayers

Oren Tirosh, Ron Kohen, Jehoshua Katzhendler, Anat Alon, Yechezkel Barenholz*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

28 Scopus citations

Abstract

Large unilamellar vesicles (120-160 nm) composed of egg phosphatidylcholine (egg PC) containing approximately 22 wt% of polyunsaturated fatty acids (PUFA) and various mol% (0, 10, 22, or 45) of cholesterol were exposed to oxidative stress. The hydrophilic azo compound 2,2'-azobis-(2-amidinopropane)2HCl (AAPH) which was thermally decomposed to produce a constant flux of peroxy radicals was the source of the oxidative stress (≤ 48 h incubation at 37°C). Cholesterol loss following the oxidation was up to 33%, while PUFA were more extensively damaged; loss was up to 52, 88, and 100% for C-18:2, C-20:4, and C-22:6, respectively. (ii) Oxidizability of cholesterol when quantified in absolute amount was three-fold higher when its level was 45 mol%. The interrelationship between bilayer structure, especially its lateral organization and free volume, and lipid peroxidation are discussed. Differential scanning calorimetry of oxidized multilamellar vesicles lacking cholesterol revealed that a high level of oxidative damage to egg phosphatidylcholine PUFA resulted in the loss of the gel to liquid-crystalline phase transition of egg PC (broad peak at around -8°C).

Original languageAmerican English
Pages (from-to)17-22
Number of pages6
JournalChemistry and Physics of Lipids
Volume87
Issue number1
DOIs
StatePublished - 1997

Bibliographical note

Funding Information:
This work was supported in part by The Israel-United States Science Foundation, BSF 95/318 to Y.B.

Keywords

  • Acyl chains
  • Cholesterol
  • Lipid peroxidation
  • Liposomes

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