title: A study of the phase transition behaviours of cholesterol and saturated egg lecithin, and their interaction by differential scanning calorimetry.
abstract: The thermal behaviours of hydrogenated egg lecithin (PC) and cholesterol (C) in anhydrous form and in aqueous dispersions were studied by differential scanning calorimetry. The role of C in phase transitions of C-PC mixtures prepared by physical mixing or coprecipitating from chloroform has been examined. C underwent a phase transition at 34 degrees C and a second one at 76-78 degrees C which depended on the thermal history of the samples. C lowered the gel to liquid crystalline phase transition temperature (Tt) of the aqueous dispersions prepared from C-PC coprecipitates, broadened the endothermic peak at the Tt, and at 1:1 molar ratio the C-PC system did not undergo the phase transition. The C-PC interaction was observed below the Tt. In aqueous dispersions prepared from C-PC physical mixtures, C did not influence the phase transition and acted like an inert diluent. Pellets prepared from C-PC mixtures formed myelin bodies as a result of their erosion in 0.185 M borate buffer (pH 7.4) at below Tt, but the thermal behaviours of these myelin bodies were different for pellets prepared differently. Addition of bovine serum albumin (BSA) (10%, w/w) to the physical mixtures or coprecipitates of C-PC, or to PC alone did not show any effect on the thermal behaviours of their aqueous dispersions at the Tt.
authors: Department of Pharmacy, University of Queensland, Brisbane, Australia.
authors: M Z
authors: MZ
authors: Khan
authors: I G
authors: IG
authors: Tucker
mesh_terms: D002021:Buffers; D002152:Calorimetry, Differential Scanning; D002725:Chloroform; D002784:Cholesterol / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013696:Temperature
chemical_list: D002021:Buffers; D010713:Phosphatidylcholines; D012710:Serum Albumin, Bovine; D002725:Chloroform; D002784:Cholesterol