V Zia1, R A Rajewski, V J Stella. 1. Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence 66047, USA.
Abstract
PURPOSE: To understand the role of degree of substitution on binding of molecules to beta-Cyclodextrins (beta-CDs) with varying degrees of sulfobutyl ether (SBE) substitution. METHODS: Using UV spectroscopy, complexation constants of molecules to SBE-beta-CDs were estimated as a function of temperature, allowing for calculation of thermodynamic parameters, including the enthalpy and entropy of binding. RESULTS: Binding constants of various molecules to SBE-beta-CDs did not show a uniform trend to total degree of SBE substitution. However, a distinct pattern was observed with the enthalpy and entropy of complexation. The results showed the complexation of substrates to SBE-beta-CDs to be more entropy-favored as the number of SBE groups increased. This favorable entropy of interaction was compensated by a less favorable enthalpy of interaction. CONCLUSIONS: Enthalpy and entropy of complexation provided additional insight into the role that the alkylsulfonate groups may play in the complexation of molecules with SBE-beta-CDs.
PURPOSE: To understand the role of degree of substitution on binding of molecules to beta-Cyclodextrins (beta-CDs) with varying degrees of sulfobutyl ether (SBE) substitution. METHODS: Using UV spectroscopy, complexation constants of molecules to SBE-beta-CDs were estimated as a function of temperature, allowing for calculation of thermodynamic parameters, including the enthalpy and entropy of binding. RESULTS: Binding constants of various molecules to SBE-beta-CDs did not show a uniform trend to total degree of SBE substitution. However, a distinct pattern was observed with the enthalpy and entropy of complexation. The results showed the complexation of substrates to SBE-beta-CDs to be more entropy-favored as the number of SBE groups increased. This favorable entropy of interaction was compensated by a less favorable enthalpy of interaction. CONCLUSIONS: Enthalpy and entropy of complexation provided additional insight into the role that the alkylsulfonate groups may play in the complexation of molecules with SBE-beta-CDs.
Authors: R J Tait; D J Skanchy; D P Thompson; N C Chetwyn; D A Dunshee; R A Rajewski; V J Stella; J F Stobaugh Journal: J Pharm Biomed Anal Date: 1992-09 Impact factor: 3.935