SPECTROSCOPIC STUDY OF THE INTERACTION OF CATECHIN WITH ALPHA-CYCLODEXTRIN, BETA-CYCLODEXTRIN, AND GAMMA-CYCLODEXTRIN

The inclusion complex of catechin with cyclodextrins (CDxs) is examine d by the use of H-1 NMR, UV, and circular dichroism spectroscopies. Th e UV measurements demonstrate the existence of additional absorbing sp ecies of catechin in the presence of beta-CDx. The H-1 NMR provides ev idence for the formation of inclusional complexes between catechin and beta- and gamma-CDxs through changes in the chemical shifts of the pr oton resonances of catechin and that of the protons inside the CDx act ivity. The apparent formation constant is estimated by use of circular dichroism.