EFFECT OF SATURATED UNSATURATED PHOSPHATIDYLCHOLINE RATIO ON THE STABILITY OF LIPOSOME-ENCAPSULATED HEMOGLOBIN/

The influence of different combinations of saturated and unsaturated p hosphatidylcholines (PCs) as well as addition of alpha-tocopherol on l ipid peroxidation and particle size change was analyzed. Because unsat urated egg PC was susceptible to peroxidation, partially hydrogenated egg PC or hydrogenated egg PC (H-PC) was frequently used instead of eg g PC. The efficacy of another alternative with combinations of saturat ed and unsaturated PCs was investigated. Oxidation can be inhibited by adding alpha-tocopherol in the lipid formulation or by using differen t combinations of H-PC and PC. Adding alpha-tocopherol was shown to ca use physical instability of liposomes, and increase the possibility of aggregation. Increasing the H-PC content in the liposome formulation will effectively reduce the peroxidation. The stability of liposome wa s dependent on both alpha-tocopherol and H-PC to PC ratio. Encapsulati ng hemoglobin in the liposome would promote the lipid peroxidation. (C ) 1998 Elsevier Science B.V. All rights reserved.