title: Gallated form of tea catechin, not nongallated form, increases fecal starch excretion in rats.
abstract: This study was carried out to elucidate the structural advantage of a gallated form of tea catechin on modulating bioavailability of dietary starch in rats. Animal studies demonstrated that the addition of 0.5% (w/w) (-)-epigallocatechin gallate (EGCG) to the diet brought about a significant increase in the starch content in the feces collected for 2 d at the fourth week of feeding over that with the control diet. Of the gross starch that the rats consumed from their respective diets during the fecal collection period, 0.1% (for control diet) and 1.9% (for EGCG diet) were estimated to be excreted in the feces. However, such a significant increase in the fecal excretion of starch by the EGCG diet was lost by undergoing hydrolysis of EGCG to (-)-epigallocatechin (EGC) and gallic acid (GA). In vitro investigation also showed that EGCG inhibited porcine pancreatic α-amylase activity in a concentration-dependent fashion, whereas the hydrolyzed preparation (the mixture of EGC and GA) exhibited a lack of the inhibitory activity for α-amylase. The modification of dietary starch digestion by inhibiting intestinal α-amylase activity with EGCG may be responsible at least in part for increasing fecal output of starch in rats. Thus, the attachment of a galloyl moiety to the tea flavan-3-ol skeleton may be of key importance for reducing intestinal digestion of dietary starch in rats.
authors.affiliation: Department of Health and Nutrition, Tokyo Kasei Gakuin University, Tokyo, Japan. tunno@kasei-gakuin.ac.jp
authors.forename: Tomonori
authors.initials: T
authors.lastname: Unno
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Matsumoto
authors.forename: Yukari
authors.initials: Y
authors.lastname: Yamamoto
mesh_terms: D000818:Animals; D002392:Catechin / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D004040:Dietary Carbohydrates / Q000378:metabolism; D005243:Feces / Q000737:chemistry*; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000187:drug effects; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D013213:Starch / Q000378:metabolism*; D018709:Statistics, Nonparametric; D013662:Tea / Q000737:chemistry*; D000516:alpha-Amylases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D004040:Dietary Carbohydrates; D013662:Tea; D002392:Catechin; D013213:Starch; C045651:epigallocatechin gallate; D000516:alpha-Amylases; C057580:gallocatechol