Spectrofluorometric, thermal, and molecular mechanics studies of the inclusion complexation of selected imidazoline-derived drugs with β-cyclodextrin in aqueous media

Abdulilah A. Dawoud, Nathir Al-Rawashdeh

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

The inclusion complexes of selected imidazoline-derived drugs, namely Antazoline (AN), Naphazoline (NP) and Xylometazoline (XM) with β-cyclodextrin (β-CD) were investigated using steady-state fluorescence spectroscopy, differential scanning calorimetry (DSC), and molecular mechanics (MM) calculations and modeling. The modified form of the Benesi-Hildebrand relation was employed for estimating the formation constant (Kf) of the 1:1 inclusion complexes, which was applied based on measuring the variation in the fluorescence intensity of the guest molecule as a function of growing β-CD concentration. On the other hand, the formation of the inclusion complexes was verified by analyzing solid samples of the complexes using DSC. The thermodynamics of the inclusion complexation, standard enthalpy (ΔH°) and entropy changes -(ΔS°) were obtained from the temperature-dependence of Kf. Obtained values of ΔH° and ΔS° indicated that the inclusion process favorably proceeds through enthalpy changes that was sufficiently predominant to compensate for the unfavorable entropy changes. MM calculations revealed that the proposed drugs molecules can form 1:1 inclusion complexes with β-CD that are stabilized predominantly through van der Waals forces. In addition, MM calculation provided the energetically favored configuration of the inclusion complexes, where NP and XM can be included inside the β-CD cavity through its wide rim, whereas AN can penetrate through the narrow rim of the β-CD cavity.

Original languageEnglish
Pages (from-to)293-301
Number of pages9
JournalJournal of Inclusion Phenomena and Macrocyclic Chemistry
Volume60
Issue number3-4
DOIs
Publication statusPublished - Apr 2008
Externally publishedYes

Keywords

  • B-cyclodextrin
  • Differential scanning calorimetry
  • Fluorescence
  • Imidazoline-derived drugs
  • Inclusion complex
  • Molecular mechanics

ASJC Scopus subject areas

  • Food Science
  • General Chemistry
  • Condensed Matter Physics

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