title: Structures of (-)-epicatechin glucuronide identified from plasma and urine after oral ingestion of (-)-epicatechin: differences between human and rat.
abstract: (-)-epicatechin is one of the most potent antioxidants present in the human diet. Particularly high levels are found in black tea, apples, and chocolate. High intake of catechins has been associated with reduced risk of cardiovascular diseases. There have been several reports concerning the bioavailability of catechins, however, the chemical structure of (-)-epicatechin metabolites in blood, tissues, and urine remains unclear. In the present study, we purified and elucidated the chemical structure of (-)-epicatechin metabolites in human and rat urine after oral administration. Three metabolites were purified from human urine including (-)-epicatechin-3'-O-glucuronide, 4'-O-methyl-(-)-epicatechin-3'-O-glucuronide, and 4'-O-methyl-(-)-epicatechin-5 or 7-O-glucuronide, according to 1H- and 13C-NMR, HMBC, and LC-MS analyses. The metabolites purified from rat urine were 3'-O-methyl-(-)-epicatechin, (-)-epicatechin-7-O-glucuronide, and 3'-O-methyl-(-)-epicatechin-7-O-glucuronide. These compounds were also detected in the blood of humans and rats by LC-MS. The presence of these metabolites in blood and urine suggests that catechins are metabolized and circulated in the body after administration of catechin-containing foods.
authors.affiliation: Health and Bioscience Laboratories, Meiji Seika Kaisha Ltd, Saitama, Japan. midori_natsume@meiji.co.jp
authors.forename: Midori
authors.initials: M
authors.lastname: Natsume
authors.forename: Naomi
authors.initials: N
authors.lastname: Osakabe
authors.forename: Makoto
authors.initials: M
authors.lastname: Oyama
authors.forename: Motoko
authors.initials: M
authors.lastname: Sasaki
authors.forename: Seigo
authors.initials: S
authors.lastname: Baba
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Nakamura
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Osawa
authors.forename: Junji
authors.initials: J
authors.lastname: Terao
mesh_terms: D000284:Administration, Oral; D000328:Adult; D000818:Animals; D002392:Catechin / Q000008:administration & dosage* / Q000031:analogs & derivatives / Q000097:blood* / Q000737:chemistry* / Q000652:urine*; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005609:Free Radicals; D008401:Gas Chromatography-Mass Spectrometry; D005965:Glucuronates / Q000097:blood* / Q000737:chemistry* / Q000652:urine*; D020723:Glucuronic Acid / Q000097:blood* / Q000737:chemistry* / Q000652:urine*; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008956:Models, Chemical; D051381:Rats; D017207:Rats, Sprague-Dawley; D013045:Species Specificity; D013997:Time Factors
chemical_list: D005609:Free Radicals; D005965:Glucuronates; C480662:epicatechin-3'-O-glucuronide; D020723:Glucuronic Acid; D002392:Catechin