Studies on peroxidation processes of model membranes: role of pyrophosphate.
Phosphate-containing compounds of both a lipophilic (dipalmitoylphosphatidic acid, lysophosphatidic acid and dicetylphosphate) and hydrophilic nature (orthophosphate, 3-phosphoglyceric acid, 2,3-diphosphoglyceric acid and pyrophosphate in particular) have been found to inhibit to varying degrees the lipoperoxidation of liposomal arachidonic acid. Lipophilic compounds seem to act exclusively at the lipid component level of the membrane, giving rise to polyanionic complexes with free arachidonic acid or its radical derivatives that could bind the Fe2+ strongly (thereby inhibiting the iron pro-oxidation activity) or to minimize the lateral mobility of the lipid radicals (thereby reducing the propagation of lipid peroxidation). The high antiperoxidative power of hydrophilic compounds, and in particular of pyrophosphate, must, on the contrary, be primarily attributed to their ability to form very stable complexes with the Fe present in the solution surrounding the liposomal membranes. The possible contribution of these physiological compounds to the in vivo defense mechanism against radical-induced damage is discussed.
Cervato
G
G
Dept. of Medical Chemistry and Biochemistry, Faculty of Medicine, University of Milan, Italy.
Viani
P
P
Cestaro
B
B
D016718:Arachidonic Acid; D001095:Arachidonic Acids / Q000378:metabolism; D002850:Chromatography, Gel; D011756:Diphosphates / Q000494:pharmacology*; D005609:Free Radicals; D015227:Lipid Peroxidation / Q000187:drug effects*; D008081:Liposomes / Q000378:metabolism; D008567:Membranes, Artificial; D008954:Models, Biological; D013050:Spectrometry, Fluorescence
D001095:Arachidonic Acids; D011756:Diphosphates; D005609:Free Radicals; D008081:Liposomes; D008567:Membranes, Artificial; D016718:Arachidonic Acid