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Cholesterol protects the phospholipid bilayer from oxidative damage
T Parasassi1, A M Giusti, M Raimondi
1Istituto di Medicina Sperimentale, CNR, Roma, Italy.
Free Radical Biology & Medicine
|October 1, 1995
Summary
Ionizing radiation causes oxidative damage to phospholipid membranes, detectable via fluorescence lifetime distribution of 1,6-diphenyl-1,3,5-hexatriene. Cholesterol significantly reduces this radiation-induced hydroperoxide damage.
Area of Science:
- Biophysics
- Radiation Chemistry
- Membrane Biophysics
Background:
- Phospholipid membranes are susceptible to oxidative damage from ionizing radiation.
- This damage involves the formation of hydroperoxide residues on acyl chains.
- Such damage can alter membrane structure and permeability.
Purpose of the Study:
- To establish a method for detecting radiation-induced oxidative damage in phospholipid membranes.
- To investigate the role of cholesterol in mitigating this damage.
Main Methods:
- Utilizing the fluorescence lifetime distribution of 1,6-diphenyl-1,3,5-hexatriene as a probe.
- Employing a chemiluminescence assay to quantify hydroperoxide production.
- Irradiating phospholipid bilayers with and without cholesterol.
Main Results:
- A linear relationship was found between the probe's lifetime distribution width and radiation dose.
- Cholesterol significantly reduced the concentration of radiation-induced hydroperoxides in phospholipid bilayers.
- Cholesterol's packing effect likely hinders radical chain reactions in unsaturated lipids.
Conclusions:
- Fluorescence lifetime distribution is a viable method for detecting oxidative damage in membranes.
- Cholesterol acts as a protective agent against ionizing radiation-induced membrane damage.
- Steric hindrance by cholesterol is a probable mechanism for reducing hydroperoxide formation.