NMR spectroscopic characterization of inclusion complexes comprising cyclodextrins and gallated catechins in aqueous solution: cavity size dependency

✍ Scribed by Takashi Ishizu; Hiroyuki Tsutsumi; Hideji Yamamoto; Kazunobu Harano

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: English
• Weight: 253 KB
• Volume: 47
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.2383

✦ Synopsis

Abstract

The structure of inclusion complexes of γ‐cyclodextrin (γ‐CD), (–)‐gallocatechin gallate (GCg), and (–)‐epigallocatechin gallate (EGCg) in D~2~O was investigated using several NMR techniques. GCg formed a 1:1 inclusion complex with γ‐CD in which the A and C rings of GCg were inserted deep at the head of the A ring into the γ‐CD cavity from the wide secondary hydroxyl group side. In the 1:1 inclusion complex with GCg and γ‐CD, the GCg moiety maintained a conformation in which the B and B′ rings of GCg took both pseudoequatorial positions with respect to the C ring. The structure of the inclusion complex of GCg and γ‐CD obtained from NMR experiments supported well that determined from PM6 semiempirical SCF MO calculations. However, ^1^H NMR experiments suggested that EGCg did not form any inclusion complex with γ‐CD in D~2~O. The marked difference between GCg and EGCg in inclusion behavior toward γ‐CD may be explained in terms of the stabilization energy calculated with the PM6 method. Copyright © 2008 John Wiley & Sons, Ltd.