Structural and physicochemical characterization of the inclusion complexes of cyclomaltooligosaccharides (cyclodextrins) with melatonin
- Autori: Bongiorno, D.; Ceraulo, L.; Mele, A.; Panzeri, W.; Selva, A.; TURCO LIVERI, V.
- Anno di pubblicazione: 2002
- Tipologia: Articolo in rivista (Articolo in rivista)
- Parole Chiave: Calorimetry; Cyclodextrins; Inclusion complexes; Mass spectrometry; Melatonin; NMR; Solubility; Analytical Chemistry; Biochemistry; Organic Chemistry
- OA Link: http://hdl.handle.net/10447/243656
Abstract
The stoichiometry, geometry, stability, and solubility of the inclusion complexes of melatonin (MLT) with native cyclomaltooligosaccharides (α-, β- or γ-cyclodextrins, CDs) are determined experimentally by high-resolution NMR spectroscopy, calorimetric and solubility measurements, and mass spectrometry. The observed differences are discussed in terms of molecular recognition expression of the host-guest (h-g) interactions within the hydrophobic CDs cavities of different size. The 1:1 h-g stoichiometry in water solution prevails at low CD concentrations; the trend to form higher order associations is observed at increasing CD concentrations. The stability order β-CD>γ-CD>α-CD for the complexes in water solution and β-CD>α-CD>γ-CD for the protonated or alkali-cationated complexes in the gas phase are rationalized on the grounds of the structural data from NMR spectroscopy and of the thermodynamic parameters from calorimetric measurements. © 2002 Elsevier Science Ltd. All rights reserved.