ScienceAsia 28 (2002) : 263-270 |doi: 10.2306/scienceasia1513-1874.2002.28.263

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

Pornthep Sompornpisut^*, Nutsima Deechalao, Jitraporn Vongsvivut

ABSTRACT: An inclusion host-guest complex between beta-cyclodextrin (beta-CD) and L-phenylalanine (LPhe) was investigated using ¹H nuclear magnetic resonance spectroscopy and molecular docking techniques. ¹H chemical shift changes of beta-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 beta-CD. Results from NMR and docking simulation are in good agreement with the x-ray structures of beta-CD/L-phenylalanine derivatives.

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Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai Road, Bangkok 10330, Thailand.


*Corresponding author, E-mail: spornthe@pioneer.netserv.chula.ac.th

Received 9 Jul 1999, Accepted 7 Jan 2002