TY - JOUR
T1 - Damage to liposomal lipids
T2 - Protection by antioxidants and cholesterol- mediated dehydration
AU - Samuni, Ayelet M.
AU - Lipman, Alexander
AU - Barenholz, Yechezkel
PY - 2000/4
Y1 - 2000/4
N2 - Liposomes composed of egg phosphatidylcholine (EPC) (13.4% of the acyl chains being polyunsaturated fatty acids (PUFA)) and EPC/cholesterol (10:1 mol/mol) were studied for factors that affect liposomal lipid oxidative damage and hydrolysis upon long-term (16 months) storage. Factors studied include: (1) levels of lipid/water interface hydration, related to the presence of cholesterol in the lipid bilayer; (2) the membrane-associated antioxidant vitamin E; (3) the water-soluble antioxidant Tempol; and (4) exposure to light. Liposomal dispersions were stored at room temperature, either exposed to or protected from daylight, for a period of 16 months. Chemical and physical changes were monitored at several time points to assess oxidative and hydrolytic degradation of liposomal lipids. The conclusions of the study are: (1) PUFA are the most sensitive component of the liposome bilayer to oxidative degradation damage during long-term storage; (2) EPC liposomes are more sensitive to degradation during storage than EPC/cholesterol liposomes, the presence of cholesterol in the lipid bilayer having a protective effect, probably due to its effect in decreasing the lipid-bilayer hydration; (3) oxidative degradation is the major process during long-term storage, having an earlier onset than the hydrolytic degradation; and (4) Tempol provided significantly better protection than vitamin E to EPC liposomal PUFA against oxidative damage during long-term storage. The relevance of cholesterol's presence, as a 'drying agent', in membranes containing PUFA to resistance of biological membranes to oxidative damage is discussed. (C) 2000 Elsevier Science Ireland Ltd.
AB - Liposomes composed of egg phosphatidylcholine (EPC) (13.4% of the acyl chains being polyunsaturated fatty acids (PUFA)) and EPC/cholesterol (10:1 mol/mol) were studied for factors that affect liposomal lipid oxidative damage and hydrolysis upon long-term (16 months) storage. Factors studied include: (1) levels of lipid/water interface hydration, related to the presence of cholesterol in the lipid bilayer; (2) the membrane-associated antioxidant vitamin E; (3) the water-soluble antioxidant Tempol; and (4) exposure to light. Liposomal dispersions were stored at room temperature, either exposed to or protected from daylight, for a period of 16 months. Chemical and physical changes were monitored at several time points to assess oxidative and hydrolytic degradation of liposomal lipids. The conclusions of the study are: (1) PUFA are the most sensitive component of the liposome bilayer to oxidative degradation damage during long-term storage; (2) EPC liposomes are more sensitive to degradation during storage than EPC/cholesterol liposomes, the presence of cholesterol in the lipid bilayer having a protective effect, probably due to its effect in decreasing the lipid-bilayer hydration; (3) oxidative degradation is the major process during long-term storage, having an earlier onset than the hydrolytic degradation; and (4) Tempol provided significantly better protection than vitamin E to EPC liposomal PUFA against oxidative damage during long-term storage. The relevance of cholesterol's presence, as a 'drying agent', in membranes containing PUFA to resistance of biological membranes to oxidative damage is discussed. (C) 2000 Elsevier Science Ireland Ltd.
KW - Lipid peroxidation
KW - Liposomes
KW - Nitroxides
KW - Stability
KW - Tempol
KW - Vitamin E
UR - http://www.scopus.com/inward/record.url?scp=0033847610&partnerID=8YFLogxK
U2 - 10.1016/S0009-3084(99)00136-X
DO - 10.1016/S0009-3084(99)00136-X
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C2 - 10823461
AN - SCOPUS:0033847610
SN - 0009-3084
VL - 105
SP - 121
EP - 134
JO - Chemistry and Physics of Lipids
JF - Chemistry and Physics of Lipids
IS - 2
ER -