Free Radical-Mediated Lipid Peroxidation in Cells: Oxidizability Is a Function of Cell Lipid bis-Allylic Hydrogen Content

Abstract

Oxidizability of lipids in homogeneous solution varies linearly with the extent of their unsaturation. In vitro cellular, as well as in vivo, studies of oxidizability have generally relied upon chemical indicators of peroxidation such as thiobarbituric acid-reactive substances. To examine the oxidizability of lipids in cells, we have measured oxygen uptake and, using electron paramagnetic resonance spin trapping with alpha-(1-oxo-4-pyridyl)-N-tert-butylnitrone (POBN), the real time generation of lipid-derived free radicals. We have used our experimental in vitro cellular lipid modification model to examine the rate and extent of lipid peroxidation versus the degree of lipid unsaturation in L1210 murine leukemia cells. Lipid peroxidation was stimulated using the prooxidants iron, ascorbate, and the ether lipid compound 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine. We did a total cellular lipid analysis to determine the number of lipid carbon-carbon double bonds contained in L1210 cells enriched with eight fatty acids of different degrees of unsaturation. We found in cellular lipids that (i) lipid chain length had no apparent effect on the rate or extent of radical formation; (ii) the maximum amount of lipid radical generated increases with the total number of bis-allylic positions in the cellular lipids; and, most importantly, (iii) the rate of cellular lipid peroxidation increases exponentially with the number of bis-allylic positions. Our quantitative results clearly demonstrate, for the first time, that the number of bis-allylic positions contained in the cellular lipids of intact cells determines their susceptibility, i.e., oxidizability, to free radical-mediated peroxidative events.

A diet containing rapeseed oil-based fats does not increase lipid peroxidation in humans when compared to a diet rich in saturated fatty acids

“…However, intervention studies with PUFA-rich diets have also shown that the susceptibility of lipoproteins to oxidation was increased and that very high intakes of PUFAs may carry nonfavourable effects on the development of atherosclerosis (Tsimikas & Reaven, 1998;Eritsland, 2000). The oxidisability of fatty acids is considered to be dependent on the degree of unsaturation (Wagner et al, 1994;Porter et al, 1995). Therefore, dietary recommendations regarding fat intake and quality include a maximum level of the PUFA intake.…”

“…The oxidisability of fatty acids is considered to be directly dependent on their degree of unsaturation (Wagner et al, 1994;Porter et al, 1995). Rapeseed oil contains a high content of oleic acid (18:1) and linoleic acid (18:2 n-6) but also considerable amounts of a-linolenic acid, which is an easily oxidised fatty acid.…”

Amplification of oxidative stress by a dual stimuli-responsive hybrid drug enhances cancer cell death

“…However, overproduction of H 2 O 2 and other ROS causes oxidative stress, leading to cellular damages and subsequent functional decline of organ systems 4,5 . Therefore, it is crucial for normal cells to maintain ROS homeostasis to control the ROS level and overcome the potential toxicity of ROS 6 .…”

Singlet Oxygen Toxicity Is Cell Line‐dependent: A Study of Lipid Peroxidation in Nine Leukemia Cell Lines

“…The DBI and total lipid of all cell lines were determined following Wagner et al (14). Briefly, cells (2 ϫ 10 6 ) were washed and extracted with chloroform : methanol 2:1 (vol/vol).…”

“…The oxidizability of PUFA by 1 O 2 will be proportional to the double bound index (DBI). The DBI is the average number of double bonds per fatty acid chain in the cell (14). Thus, a logical hypothesis is that cells with a higher DBI should be more sensitive to 1 O 2 phototoxicity compared to cells with low PUFA content.…”