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Characterization of aspartame-cyclodextrin complexation
Tamás Sohajda1, Szabolcs Béni, Erzsébet Varga
1Semmelweis University, Department of Pharmaceutical Chemistry, 1092 Budapest, Hogyes Endre u. 9, Hungary.
Journal of Pharmaceutical and Biomedical Analysis
|July 10, 2009
Summary
Aspartame forms stable inclusion complexes with beta-cyclodextrins, particularly acetylated derivatives. Complex stability depends on cyclodextrin purity and size, with the aromatic ring of aspartame entering the wider end of the cyclodextrin cavity.
Area of Science:
- Supramolecular Chemistry
- Analytical Chemistry
- Pharmaceutical Sciences
Background:
- Aspartame, an artificial sweetener, can form inclusion complexes with cyclodextrins.
- Understanding these complexes is crucial for drug delivery and formulation stability.
- Cyclodextrin properties significantly influence complexation.
Purpose of the Study:
- To investigate the inclusion complex formation between aspartame and various cyclodextrins.
- To determine the optimal cyclodextrin derivatives for stable aspartame complexation.
- To elucidate the structural and chemical factors governing complex stability.
Main Methods:
- Protonation constants of aspartame determined by NMR-pH titration.
- Complex stability studied using 1H NMR titration and capillary electrophoresis at different pH values.
- Structural aspects investigated by 2D ROESY NMR and molecular modeling.
Main Results:
- Protonation constants of aspartame: log K1=7.83 and log K2=2.96.
- Beta-cyclodextrins and their derivatives showed the highest suitability for complexation.
- Acetylated beta-cyclodextrin (DS=7) exhibited the highest complex stability.
- Cyclodextrin purity positively impacted complexation; degree of substitution had no clear effect.
- Molecular modeling confirmed aspartame's aromatic ring enters the wider end of the cyclodextrin cavity.
Conclusions:
- Beta-cyclodextrins are effective hosts for aspartame inclusion complex formation.
- Cyclodextrin purity is a key factor for enhanced complex stability.
- The study provides insights into optimizing cyclodextrin-based formulations for aspartame.
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