title: Characterization of creaming precipitate of tea catechins and caffeine in aqueous solution.
abstract: The content of a crude precipitate formed by creaming, which was made from a catechin mixture and caffeine, was investigated by an integral volume of H-2 proton signals of tea catechins in the (1)H-NMR spectrum. Gallated catechins formed a crude precipitate more predominantly than non-gallated catechins. The 2,3-cis-non-gallated catechin (-)-epicatechin (EC) formed a 1:1 complex with caffeine, and 2,3-cis-gallated catechin (-)-epicatechin gallate (ECg) formed a 2:4 complex with caffeine. The π-π complexation site of EC with caffeine was only the A ring, whereas that of ECg included all aromatic rings, A, B, and B'. It was thought that the hydrophobicity of the 2:4 complex of ECg and caffeine was stronger than that of the 1:1 complex of EC and caffeine, with the result that the 2:4 complex of ECg and caffeine precipitated by creaming more predominantly than the 1:1 complex of EC and caffeine in aqueous solution.
authors.affiliation: Faculty of Pharmacy and Pharmaceutical Sciences, Fukuyama University, Sanzo Gakuen-cho 1, Fukuyama, Hiroshima 729-0292, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Sato
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Kinoshita
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tsutsumi
authors.forename: Hideji
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Takashi
authors.initials: T
authors.lastname: Ishizu
mesh_terms: D002110:Caffeine / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry*; D011232:Chemical Precipitation; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D012996:Solutions
chemical_list: D012996:Solutions; D002110:Caffeine; D002392:Catechin; C062669:epicatechin gallate