title: Tea polyphenols inhibit the transport of dietary phenolic acids mediated by the monocarboxylic acid transporter (MCT) in intestinal Caco-2 cell monolayers.
abstract: It was previously reported that a fluorescent marker dye, fluorescein, is transported via the monocarboxylic acid transporter (MCT). Fluorescein transport was competitively inhibited by MCT substrates such as ferulic and salicylic acids. Tea polyphenols, in particular, epigallocatechin gallate (EGCg) and epicatechin gallate (ECg), inhibited the transport of fluorescein. Tea polyphenols also inhibited the transport of salicylic and ferulic acids, suggesting tea polyphenols might be substrates of MCT. However, the transepithelial flux of tea polyphenols was much lower than that of the MCT substrates and was inversely correlated with the paracellular permeability of Caco-2 cell monolayers. These findings suggest that tea polyphenols are not substrates but inhibitors of MCT. Furthermore, the transepithelial transport of these polyphenols is mainly via paracellular diffusion. However, directional transport of ECg and EGCg from the basolateral to the apical side was observed, indicating that the behavior of tea polyphenols in the intestinal epithelium is complex.
authors.affiliation: Applied Bioresearch Center, Research and Development Department, Kirin Brewery Company, Ltd., 3 Miyaharacho, Takasaki-shi, Gunma 370-1295, Japan. konishiy@kirin.co.jp
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Konishi
authors.forename: Shoko
authors.initials: S
authors.lastname: Kobayashi
authors.forename: Makoto
authors.initials: M
authors.lastname: Shimizu
mesh_terms: D001692:Biological Transport / Q000187:drug effects; D018938:Caco-2 Cells; D002392:Catechin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D004847:Epithelial Cells / Q000378:metabolism / Q000648:ultrastructure; D005419:Flavonoids / Q000378:metabolism / Q000494:pharmacology*; D019793:Fluorescein / Q000378:metabolism; D005456:Fluorescent Dyes; D006801:Humans; D062385:Hydroxybenzoates / Q000378:metabolism*; D007408:Intestinal Absorption / Q000187:drug effects; D007413:Intestinal Mucosa / Q000378:metabolism*; D007422:Intestines / Q000648:ultrastructure; D027501:Monocarboxylic Acid Transporters / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010636:Phenols / Q000378:metabolism / Q000494:pharmacology*; D059808:Polyphenols; D013662:Tea / Q000737:chemistry*
chemical_list: D005419:Flavonoids; D005456:Fluorescent Dyes; D062385:Hydroxybenzoates; D027501:Monocarboxylic Acid Transporters; D010636:Phenols; D059808:Polyphenols; D013662:Tea; D002392:Catechin; C062669:epicatechin gallate; C045651:epigallocatechin gallate; C017616:phenolic acid; D019793:Fluorescein