Omega 3 fatty acid are very bioactive, despite a high susceptibility to non-enzymatic peroxidation.
Omega 3 and other poly unsaturated fatty acids play an important role in "linked" reactions such as prostaglandin biosynthesis. For example EPA is incorporated into phospholipids at A2 position in the plasma membrane. Phospholipase A2 releases them and are immediately cyclated by fatty acid cyclo-oxygenases to produce prostaglandins. peroxidized or epoxides of fatty acids are not incorporated into PL moieties an are thus not functional in this situation. sub-cellular compartmentalization of poly unsaturated fatty acids can protect them from non-enzymatic oxidation. It is generally accepted that many of the biological activities of omega 3 are due to their cell specific metabolites.
Omega 3 and other poly unsaturated fatty acids play an important role in "linked" reactions such as prostaglandin biosynthesis. For example EPA is incorporated into phospholipids at A2 position in the plasma membrane. Phospholipase A2 releases them and are immediately cyclated by fatty acid cyclo-oxygenases to produce prostaglandins. peroxidized or epoxides of fatty acids are not incorporated into PL moieties an are thus not functional in this situation. sub-cellular compartmentalization of poly unsaturated fatty acids can protect them from non-enzymatic oxidation. It is generally accepted that many of the biological activities of omega 3 are due to their cell specific metabolites.
That is true that many of the biological activities of omega 3 long chain PUFA are linked to their enzymatic metabolites such as PGs, LTs and resolvin/protectin..etc. However, non-enzymatic metabolites are also produced in abundance in vivo. Several in vitro experiments demonstrated important action of non-enzymatic métabolites such as neuroprostanes namely on inflammatory pathways.
Dear Cecile The major issue is that, as you would expect for the structure, the oxidation of poly unsaturated fatty acids will give several reactions depending of the amount of the oxidative reactant. It has been well described in literatura minor modifications and oxidations of PUFA do not disturb the interaction of the fatty acid with the membrane transporter, whcih can also be metabolized through beta oxidation at least in part. Onde of the intteresting results positioned the anti oxidants like probucol and the peroxisome enhancers benzofibrate good compounds to decrease the inflammatory response. If the fatty acid however it is bound in a phospholipid or as other part of complex lipid in the surface of lipoprotein, scavenger receptors then would play the important role as the promoters of inflammatory response. So the simple question has two answers depending on how you assess the experiments
regards,
Arachidonyl-containing lipids are peroxidized to PGF2-like compounds, termed F2-isoprostanes. They are formed by peroxidation of arachidonate independent of the cyclooxygenase. Deficiencies in antioxidants in vivo are associated with increased IsoP formation. Antioxidants decrease IsoP levels in animals and humans.
IsoP levels are increased in animal models of human diseases and human disorders associated with oxidant stress. They exert potent biological activity. Isoprostanes are also considered as an Index of Oxidant Stress in Humans-Atherosclerosis. That means, peroxidized metabolites exert opposite effect of omega-3 fatty acids demonstrating the importance of protection of these beneficial fatty acids from oxidation/rancidity.
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