An Inclusion Complex of -Cyclodextrin-L-Phenylalanine: 1H NMR and Molecular Docking Studies

Abstract

An inclusion host-guest complex between -cyclodextrin (-CD) and L-phenylalanine (L-Phe) was investigated using 1H nuclear magnetic resonance spectroscopy and molecular docking techniques. 1H chemical shift changes of -CD were used to calculate the stability constant (Kstb) of the complex. On the basis of the Hildebrand-Benesi method, the Kstb of the 1:1 complex in D2O solution at 300 K, pD 7.6 was of 25.5 M-1, implying a fast intermolecular exchange rate process. Interestingly, docking simulation indicates the toroidal space can be occupied by L-Phe with two favorable arrangements. For the predicted model with the higher probability score, the L-Phe aromatic ring is facing to the secondary hydroxyl groups of -CD. Results from NMR and docking simulation are in good agreement with the x-ray structures of -CD/L-phenylalanine derivatives.