Spectroscopic Study of the Interaction of Catechin with .alpha.-, .beta.-, and .gamma.-Cyclodextrins

Abstract

The inclusion complex of catechin with cyclodextrins (CDxs) is examined by the use of l H NMR, UV, and circular dichroism spectroscopies. The UV measurements demonstrate the existence of additional absorbing species of catechin in the presence of P-CDx. The 'H NMR provides evidence for the formation of inclusional complexes between catechin and P-and y-CDxs through changes in the chemical shifts of the proton resonances of catechin and that of the protons inside the CDx activity. The apparent formation constant is estimated by use of circular dichroism.

Diastereomeric difference of inclusion modes between (−)‐epicatechin gallate, (−)‐epigallocatechin gallate and (+)‐gallocatechin gallate, with β‐cyclodextrin in aqueous solvent

“…4 will be discussed from the standpoint of the induced chemical shifts of ECg in the presence of β-CD ( Table 2). The proton signals due to H 2 , H 3 , H 6 , and H 8 , of ECg shifted upfield in the presence of β-CD. It has been known that signals due to protons, which do not come into close contact with the atoms on the inner surface of β-CD, tend to shift upfield because of the C-C bond anisotropy effect.…”

“…5, the exchange of the two H 6 and H 8 protons of GCg in the presence of β-CD was slow in comparison with that of GCg alone. These findings indicated that H 6 and H 8 were difficult to exchange with deuterium because of inclusion of the A ring in the cavity of β-CD in the complex β-CD and GCg.…”

Analytical characterization of a ferulic acid/γ-cyclodextrin inclusion complex

“…The interaction between ferulic acid and ␥-cyclodextrin was investigated in water/solvent by nuclear magnetic resonance spectroscopy, since this technique provides direct and detailed information on the physico-chemical interactions indicative of the formation of an inclusion complex [19][20][21][22][23].…”

Molecular modeling study of β-cyclodextrin complexes with (+)-catechin and (−)-epicatechin

“…The inclusion of CA and EC with native b-CDs has been studied and an inclusion complex with a stoichiometry of 1:1 in solid state and in aqueous solution, was attained [5,13,14]. Furthermore, the probable structures of the inclusion complexes of b-CD with CA and EC have been proposed on the basis of NMR and molecular dynamics simulations [5,13].…”