title: Improved solubility and stability of 7-hydroxy-4-methylcoumarin at different temperatures and pH values through complexation with sulfobutyl ether-β-cyclodextrin.
abstract: The inclusion complex of 7-hydroxy-4-methylcoumarin (7H4MC) with sulfobutyl ether-β-cyclodextrin (SBE-β-CD) was investigated by means of UV-vis, circular dichroism and (1)H NMR spectroscopy in phosphate buffer solutions at different temperatures and pH values. The stoichiometric ratio of the complexation was found to be 1:1 and the stability constants (KC) were estimated from phase solubility analysis. The thermodynamic parameters of standard Gibbs free energy change, ΔG(o), enthalpy change, ΔH(o), and entropy change, ΔS(o), for the complexation process were obtained by using the van't Hoff equation and Gibbs-Helmholtz equation. The large negative ΔH(o) and the small negative or positive ΔS(o) (|ΔH(o)|>|TΔS(o)|) demonstrated that the inclusion interaction was an enthalpy-driven process. The positive signal of circular dichroism indicated that 7H4MC penetrated the cavity in such a way that the transition moment of the guest chromophore was parallel to the long axis of SBE-β-CD cavity. Moreover, the (1)H NMR spectrum showed that the entire 7H4MC molecule, except the hydroxyl group, was included in the SBE-β-CD cavity.
authors.affiliation: School of Chemistry and Chemical Engineering, Liao Cheng University, Wenhua Road, Liaocheng, Shandong 252059, PR China. Electronic address: panpanliumin@163.com.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: School of Chemistry and Chemical Engineering, Liao Cheng University, Wenhua Road, Liaocheng, Shandong 252059, PR China.
authors.forename: Aiju
authors.initials: A
authors.lastname: Chen
authors.affiliation: School of Chemistry and Chemical Engineering, Liao Cheng University, Wenhua Road, Liaocheng, Shandong 252059, PR China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.affiliation: School of Chemistry and Chemical Engineering, Liao Cheng University, Wenhua Road, Liaocheng, Shandong 252059, PR China.
authors.forename: Chunmei
authors.initials: C
authors.lastname: Wang
authors.affiliation: School of Chemistry and Chemical Engineering, Liao Cheng University, Wenhua Road, Liaocheng, Shandong 252059, PR China.
authors.forename: Bingquan
authors.initials: B
authors.lastname: Wang
authors.affiliation: School of Chemistry and Chemical Engineering, Liao Cheng University, Wenhua Road, Liaocheng, Shandong 252059, PR China.
authors.forename: Dezhi
authors.initials: D
authors.lastname: Sun
mesh_terms: D004355:Drug Stability; D006863:Hydrogen-Ion Concentration; D006923:Hymecromone / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D012995:Solubility; D013696:Temperature; D013816:Thermodynamics; D047392:beta-Cyclodextrins / Q000737:chemistry*
chemical_list: D047392:beta-Cyclodextrins; C093196:SBE4-beta-cyclodextrin; D006923:Hymecromone
keywords: (1)H NMR; 7-Hydroxy-4-methylcoumarin; 7-Hydroxy-4-methylcoumarin (PubChem CID: 5280567); Circular dichroism; Complexation; Dimethyl sulfoxide-d(6) (PubChem CID: 75151); Disodium hydrogen phosphate (PubChem CID: 24203); Phase-solubility; Sodium dihydrogen phosphate (PubChem CID: 23672064); Sulfobutyl ether-β-cyclodextrin; β-Cyclodextrin (PubChem CID: 6518168)