title: alpha-Glucosidase inhibitory profile of catechins and theaflavins.
abstract: To clarify the postprandial glucose suppression effect of flavonoids, the inhibitory effects of catechins and theaflavins against alpha-glucosidase (AGH) were examined in this study. It was initially demonstrated that theaflavins and catechins preferentially inhibited maltase rather than sucrase in an immobilized AGH inhibitory assay system. For the maltase inhibitory effects of theaflavins, the effects were observed in descending order of potency of theaflavin (TF)-3-O-gallate (Gal) > TF-3,3'-di-O-Gal > TF-3'-O-Gal > TF. This suggests that the AGH inhibition induced by theaflavins is closely associated with the presence of a free hydroxyl group at the 3'-position of TF as well as the esterification of TF with a mono-Gal group. In addition, the R-configuration at the 3'-position of TF-3-O-Gal showed a higher inhibitory activity than the S-configuration. As a result of a single oral administration of maltose (2 g/kg) in rats, a significant reduction in blood glucose level was observed at a dose of 10 mg/kg of TF-3-O-Gal, demonstrating for the first time that TF-3-O-Gal can suppress glucose production from maltose through inhibition of AGH in the gut.
authors.affiliation: Department of Bioscience and Biotechnology, Division of Bioresource and Bioenvironmental Sciences, Faculty of Agriculture, Graduate School, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812-8581, Japan. tmatsui@agr.kyushu-u.ac.jp
authors.forename: Toshiro
authors.initials: T
authors.lastname: Matsui
authors.forename: Takashi
authors.initials: T
authors.lastname: Tanaka
authors.forename: Satomi
authors.initials: S
authors.lastname: Tamura
authors.forename: Asami
authors.initials: A
authors.lastname: Toshima
authors.forename: Kei
authors.initials: K
authors.lastname: Tamaya
authors.forename: Yuji
authors.initials: Y
authors.lastname: Miyata
authors.forename: Kazunari
authors.initials: K
authors.lastname: Tanaka
authors.forename: Kiyoshi
authors.initials: K
authors.lastname: Matsumoto
mesh_terms: D000818:Animals; D044946:Biflavonoids / Q000737:chemistry / Q000494:pharmacology*; D001786:Blood Glucose / Q000032:analysis; D002392:Catechin / Q000737:chemistry / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005707:Gallic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D065089:Glycoside Hydrolase Inhibitors; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013329:Structure-Activity Relationship
chemical_list: D044946:Biflavonoids; D001786:Blood Glucose; D004791:Enzyme Inhibitors; D065089:Glycoside Hydrolase Inhibitors; C056068:theaflavin; C088983:theaflavine gallate; D005707:Gallic Acid; D002392:Catechin