title: NMR spectroscopic characterization of inclusion complexes comprising cyclodextrins and gallated catechins in aqueous solution: cavity size dependency.
abstract: The structure of inclusion complexes of gamma-cyclodextrin (gamma-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 gamma-CD in which the A and C rings of GCg were inserted deep at the head of the A ring into the gamma-CD cavity from the wide secondary hydroxyl group side. In the 1:1 inclusion complex with GCg and gamma-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 gamma-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 gamma-CD in D(2)O. The marked difference between GCg and EGCg in inclusion behavior toward gamma-CD may be explained in terms of the stabilization energy calculated with the PM6 method. .
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Sanzo Gakuen-cho 1, Fukuyama, Hiroshima 729-0292, Japan. ishizu@fupharm.fukuyama-u.ac.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishizu
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsumi
authors.forename: Hideji
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Kazunobu
authors.initials: K
authors.lastname: Harano
mesh_terms: D002392:Catechin / Q000031:analogs & derivatives* / Q000737:chemistry; D003198:Computer Simulation; D017666:Deuterium Oxide / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D010316:Particle Size; D011789:Quantum Theory; D012996:Solutions; D013237:Stereoisomerism; D013816:Thermodynamics; D047408:gamma-Cyclodextrins / Q000737:chemistry*
chemical_list: D012996:Solutions; D047408:gamma-Cyclodextrins; C417940:gallocatechin gallate; D002392:Catechin; C045651:epigallocatechin gallate; D017666:Deuterium Oxide; C023792:gamma-cyclodextrin