The inverted hexagonal phase is more sensitive to hydroperoxidation than the multilamellar phase in phosphatidylcholine and phosphatidylethanolamine aqueous dispersions

Abstract

The effect of phase behaviour (hexagonal II phase and lamellar phase) on the peroxidation of membrane phospholipids has been investigated in dilinoleoyl phosphatidylcholine (DLPC)/dilinoleoyl phosphatidylethanolamine (DLPE) aqueous dispersions. Peroxidation was initiated with a water-soluble radical inducer 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPN). The phospholipid morphology was monitored by 31P-nuclear magnetic resonance (NMR). Phospholipid hydroperoxides (PCOOH and PEOOH) were determined by chemiluminescence high-performance liquid chromatography (CL-HPLC). In pH-induced phase transition systems, DLPE in the bilayer state was much less oxidized than in the hexagonal II state. In composition-induced phase transition systems, the formation of total hydroperoxides and the consumption of alpha-tocopherol in the hexagonal II phase were greater than in the bilayer phase. These data suggest that the hexagonal II phase is more sensitive to hydroperoxidation than the bilayer phase in phospholipid aqueous dispersions.

Transbilayer distribution of aminophospholipids and the oxidative stability of their component polyunsaturated fatty acids

“…A PC molecule containing unsaturated chains, such as PC18:1, would be expected to adopt a more pronounced cone shape than a PC molecule containing saturated chains, such as PC16:0, as was suggested first by Cullis and Kruijff [16,17]. Generally, increasing the molar ratio of PE in PE/PC liposomes increased lipid peroxidation in the metal ion- [21] or AAPH-mediated system [22]. Additionally, the PE-DHA in the external layer of smaller-sized liposomes could protect its component DHA from AAPH-mediated lipid peroxidation (Fig.…”

Autoxidized Phospholipids in Hexane: Nano-Self-Assemblies Studied by Synchrotron Small-Angle X-ray Scattering

“…Synchrotron small-angle X-ray scattering allowed us to retrace the process of structural changes of micelles of two kinds of phospholipids during different periods of their autoxidation in hexane. This allows us to better understand the corresponding processes occurring in biological membranes during fusion. − The rate of autoxidation may be high in these regions of membranes . This investigation demonstrates formation of different types of phospholipid aggregates in hexane during autoxidation.…”

Primary Aminophospholipids in the External Layer of Liposomes Protect Their Component Polyunsaturated Fatty Acids from 2,2‘-Azobis(2-amidinopropane)- dihydrochloride-Mediated Lipid Peroxidation

“…However, increasing the molar ratio of phosphatidylethanolamine in phosphatidylethanolamine/phosphatidylcholine liposomes decreased the amounts of external phosphatidylethanolamine in liposomes (1-4) and increased the oxygen consumption rate in the iron-induced system (5), and also increased the phosphatidylethanolamine hydroperoxide in the AAPH-mediated system (6). A higher content of phosphatidylethanolamine (above 80 mol % of total phospholipids) induces an inverted hexagonal phase that is more sensitive to AAPH-mediated lipid peroxidation than the multilamellar phase in phosphatidylcholine/phosphatidylethanolamine aqueous dispersions (6).…”

“…In model membranes, increasing the molar ratio of phosphatidylethanolamine in phosphatidylethanolamine/phosphatidylcholine liposomes decreases the amount of external phosphatidylethanolamine in a liposomal phospholipid bilayer (1)(2)(3)(4) and promotes lipid peroxidation in the metal ion-induced (5) and 2,2′-azobis(2-amidinopropane)dihydrochloride-(AAPH-) mediated ( 6) systems, respectively. A higher content of phosphatidylethanolamine induces an inverted hexagonal phase that is more sensitive to lipid peroxidation than a lamellar phase in phosphatidylcholine/phosphatidylethanolamine aqueous dispersions (6). In most studies, however, the transbilayer distribution of phosphatidylethanolamine has not been considered.…”