Calorimetric study of the solubilization of cholesterol, retinol and retinal by reversed AOT micelles

Substituent Effects on Binding Constants of Carotenoids to n-Heptane/AOT Reverse Micelles

“…Thus, knowledge of the interactions that are involved in their solubilization in reverse micelles and their dependence on functional groups that may be present in the molecule could help in understanding the analogous processes in biological membranes. D'Aprano et al (22) have studied the solubilization of retinol and retinal in n-heptane/AOT/water reverse micelles by calorimetric methods and suggested that the interactions between the double C=C bonds with the hydrophilic regions of the AOT determine their behavior. Recently it has been reported (23) that carotenoids can act as end-cap-active agents in lecithin cylindrical micelles in diverse organic solvents, but some questions still remain about the mechanism and influence of substituents in this behavior.…”

Calorimetric study of the α-tocopherol solubility in reversed AOT micelles

“…It had been shown [25] that cholesterol is preferentially solubilised in the palisade layer contrary to retinol and retinal, which prefer the aqueous microphase. Comparing structures of the α-tocopherol molecule to cholesterol, retinol and retinal (Scheme 1) we suppose that α-tocopherol molecules are preferentially located in the palisade layer of the AOT reversed micelles similarly to cholesterol.…”

“…Actually we can deduce the α-tocopherol favourable sites in AOT reversed micelles indirectly. In Table 1 the thermodynamic parameters for α-tocopherol transfer from the n-heptane to AOT reversed micelles have been compared with D'Aprano values reported for cholesterol, retinal and retinol at R = 0 and at the same temperature [25].…”

“…In the weighted nonlinear regression procedure values of the binding constant K = 45.9 kg/mol and the standard enthalpy of transfer H 0 tr = −20,197 J/mol were obtained. Because the systems under investigation did not contain water it was assumed that the binding constant, distribution constant and the molecular weight of surfactant are related in the equation [25]: Table 1 Thermodynamic parameters for transfer of α-tocopherol, from n-heptane to AOT reversed micelles in comparison to cholesterol, retinol, and retinal at R = 0 and at 25 • C (2)…”

Viscosity and Thermodynamics of Viscous Flow for the Systems of Isomeric Pentanols with Toluene

“…Recent studies about volumetric properties of these pentanols with toluene [1], viscometric and thermodynamic properties of pentanols þ n-heptane [2,3] carried out in our laboratory are considered as highly relevant to the present work. Other works of sufficient interest in relation to the present one are those of D'Aprano [4][5][6][7][8]. We report here the viscosity and relevant thermodynamic activation parameters for the binary mixtures of 1-pentanol, 2-pentanol and 3-pentanol with toluene, which as far as we know, are not available in literature.…”