Complexation of tropane alkaloids by cyclodextrins.
Λέξεις-κλειδιά
Αφηρημένη
Complexes of atropine, homatropine, scopolamine, and ipratropium with cyclodextrins were investigated by NMR and capillary electrophoresis. It has been demonstrated that tropane alkaloids form complexes with β- and γ-cyclodextrins of 1:1 stoichiometry. NMR measurements indicate the formation of complexes where both aliphatic and aromatic parts of tropane alkaloids interact with β-cyclodextrin. The stability constants of the investigated alkaloids with β- and γ-cyclodextrins were determined by capillary electrophoresis. It has been found that β-cyclodextrin forms ten times more stable complexes than γ-cyclodextrin. Moreover, the analysis of the obtained crystal structure of β-cyclodextrin/(-)-hyoscyamine complex reveals that two molecules of (-)-hyoscyamine oriented in head-to-tail mode are tightly fitted inside head-to-head β-cyclodextrin dimer. Conformation of (-)-hyoscyamine as well as scopolamine changes substantially upon complexation adapting to the cavity of β-cyclodextrin as shown by X-ray analysis, NMR and DFT calculations data.