title: Thermodynamic study on competitive solubilization of cholesterol and beta-sitosterol in bile salt micelles.
abstract: Differences in the preferential solubilization of cholesterol and competitive solubilizates (beta-sitosterol and aromatic compounds) in bile salt micelles was systematically studied by changing the molar ratio of cholesterol to competitive solubilizates. The cholesterol solubility in a mixed binary system (cholesterol and beta-sitosterol) was almost half that of the cholesterol alone system, regardless of the excess beta-sitosterol quantity added. On the other hand, the mutual solubilities of cholesterol and pyrene were not inhibited by their presence in binary mixed crystals. Finally, the cholesterol solubility was measured by changing the alkyl chain length of n-alkylbenzenes. When tetradecylbenzene was added to the bile solution, the cholesterol solubility decreased slightly and was below the original cholesterol solubility. Based on Gibbs energy change (DeltaG degrees ) for solubilization, chemicals that inhibit cholesterol solubility in their combined crystal systems showed a larger negative DeltaG degrees value than cholesterol alone.
authors.affiliation: Department of Physical Chemistry, Showa Pharmaceutical University, Higashi-Tamagawagakuen 3-3165, Machida, Tokyo, Japan. matsuoka@ac.shoyaku.ac.jp
authors.forename: Keisuke
authors.initials: K
authors.lastname: Matsuoka
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirosawa
authors.forename: Chikako
authors.initials: C
authors.lastname: Honda
authors.forename: Kazutoyo
authors.initials: K
authors.lastname: Endo
authors.forename: Yoshikiyo
authors.initials: Y
authors.lastname: Moroi
authors.forename: Osamu
authors.initials: O
authors.lastname: Shibata
mesh_terms: D001647:Bile Acids and Salts / Q000737:chemistry*; D002627:Chemistry, Physical / Q000295:instrumentation / Q000379:methods; D002784:Cholesterol / Q000737:chemistry*; D006841:Hydrocarbons, Aromatic / Q000737:chemistry; D008823:Micelles; D012855:Sitosterols / Q000737:chemistry*; D012995:Solubility; D013816:Thermodynamics
chemical_list: D001647:Bile Acids and Salts; D006841:Hydrocarbons, Aromatic; D008823:Micelles; D012855:Sitosterols; C025473:gamma-sitosterol; D002784:Cholesterol