Abstract
Liposomes have been prepared from several types of soybean hydrogenated phospholipids by using polyols. Permeability properties of liposomes thus prepared were studied by measuring the release of glucose incorporated into liposomes. The liposomes constituted with phospholipids containing large amounts of phosphatidylethanolamine or phosphatidic acid (phosphatidylcholine (PC purity: 20%) showed the high glucose permeability around room temperature and the remarkable temperature-dependent permeability. This tendency was independent with increasing the amount of PC (PC purity: 66%). The liposomes with phospholipids containing only PC (PC purity: 100%) showed very low permeability until their transition temperature (Tc) and when increasing PC concentration, the amount of trapped glucose became larger and the glucose permeability were reduced. The permeability of glucose through liposomes was enhanced drastically at their Tc, while the incorporation of cholesterol into liposomes suppressed the enhanced permeation rates of glucose above the Tc. The incorporation of 100% of cholesterol showed the most reduced effects on the temperature-dependent permeability through liposomes. The effect of polyols on the permeability of liposomes were studied. In the case of glycerin, the dependence of the permeability on temperature was much weaker than liposomes by 1, 3-butylene glycol, propylene glycol and dipropylene glycol. The increase of polyols contents had no effect on the glucose permeability of liposomes. It is suggested that the purity of phospholipids and the amount of cholesterol are the most important factors on the permeability of liposomes and the high purity of phospholipids and the incorporation of cholesterol are necessary to obtain the stable liposomes.
