Structure and intramolecular flexibility of β‐cyclodextrin complex with (−)‐epigallocatechin gallate in aqueous solvent

Abstract

The probable structure of the inclusion complex of β-cyclodextrin (β-CD) and (−)-epigallocatechin gallate (EGCg) in D₂O was investigated using several NMR techniques. EGCg formed a 1:1 complex with β-CD, in which the A ring and a portion of the C ring of EGCg were included at the head of the phenolic hydroxyl group attached to C7 of EGCg in the β-CD cavity from the wide secondary hydroxyl group side. In the 1:1 complex with β-CD, EGCg maintained the conformation in which the B and B′ rings of EGCg took pseudoequatorial and pseudoaxial positions with respect to the C ring, respectively. The structure of the inclusion complexes of β-CD and EGCg obtained from NMR experiments supported those determined from AM1 semiempirical SCF MO calculations well. Copyright © 2006 John Wiley & Sons, Ltd.