Characterization of aspartame-cyclodextrin complexation

Tamás Sohajda, Szabolcs Béni, Erzsébet Varga, Róbert Iványi, Ákos Rácz, Lajos Szente, Béla Noszál

Research output: Contribution to journalArticle

28 Citations (Scopus)

Abstract

The inclusion complex formation of aspartame (guest) and various cyclodextrins (host) were examined using 1H NMR titration and capillary electrophoresis. Initially the protonation constants of aspartame were determined by NMR-pH titration with in situ pH measurement to yield log K1 = 7.83 and log K2 = 2.96. Based on these values the stability of the complexes formed by aspartame and 21 different cyclodextrins (CDs) were studied at pH 2.5, pH 5.2 and pH 9.0 values where aspartame exists predominantly in monocationic, zwitterionic and monoanionic form, respectively. The host cyclodextrin derivatives differed in various sidechains, degree of substitution, charge and purity so that the effect of these properties could be examined systematically. Concerning size, the seven-membered beta-cyclodextrin and its derivatives have been found to be the most suitable host molecules for complexation. Highest stability was observed for the acetylated derivative with a degree of substitution of 7. The purity of the CD enhanced the complexation while the degree of substitution did not provide obvious consequences. Finally, geometric aspects of the inclusion complex were assessed by 2D ROESY NMR and molecular modelling which proved that the guest's aromatic ring enters the wider end of the host cavity.

Original languageEnglish
Pages (from-to)737-745
Number of pages9
JournalJournal of Pharmaceutical and Biomedical Analysis
Volume50
Issue number5
DOIs
Publication statusPublished - Dec 5 2009

    Fingerprint

Keywords

  • Aspartame
  • Capillary electrophoresis
  • Complex stability
  • Cyclodextrin
  • H NMR-titration
  • Inclusion complex

ASJC Scopus subject areas

  • Analytical Chemistry
  • Pharmaceutical Science
  • Drug Discovery
  • Spectroscopy
  • Clinical Biochemistry

Cite this