title: Structure- and dose-absorption relationships of coffee polyphenols.
abstract: Chlorogenic acids (CGAs) from coffee have biological effects related to human health. Thus, specific data on their bioavailability in the upper gastrointestinal tract are of high interest, since some molecules are absorbed here and so are not metabolized by colonic microflora. Up to now, no data on structure-absorption relationships for CGAs have been published, despite this being the most consumed group of polyphenols in the western diet. To address this gap, we performed ex vivo absorption experiments with pig jejunal mucosa using the Ussing chamber model (a model simulating the mucosa and its luminal/apical side). The main coffee polyphenols, caffeoylquinic acid (CQA), feruloylquinic acid (FQA), caffeic acid (CA), dicaffeoylquinic acid (diCQA), and D-(-)-quinic acid (QA), were incubated in individual experiments equivalent to gut lumen physiologically achievable concentrations (0.2-3.5 mM). Identification and quantification were performed with HPLC-diode array detection and HPLC-MS/MS. Additionally, the presence of ABC-efflux transporters was determined by Western blot analysis. The percentages of initially applied CGAs that were absorbed through the jejunal pig mucosa were, in increasing order: diCQA, trace; CQA, ≈ 1%; CA, ≈ 1.5%; FQA, ≈ 2%; and QA, ≈ 4%. No differences were observed within the CGA subgroups. Dose-absorption experiments with 5-CQA suggested a passive diffusion (nonsaturable absorption and a linear dose-flux relationship) and its secretion was affected by NaN3 , indicating an active efflux. The ABC-efflux transporters MDR 1 and MRP 2 were identified in pig jejunal mucosa for the first time. We conclude that active efflux plays a significant role in CGA bioavailability and, further, that the mechanism of CGA absorption in the jejunum is governed by their physicochemical properties.
authors.affiliation: Division of Chemistry, Department of Food Chemistry and Toxicology, Molecular Nutrition, University of Kaiserslautern, Kaiserslautern, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Erk
authors.forename: Johanna
authors.initials: J
authors.lastname: Hauser
authors.forename: Gary
authors.initials: G
authors.lastname: Williamson
authors.forename: Mathieu
authors.initials: M
authors.lastname: Renouf
authors.forename: Heike
authors.initials: H
authors.lastname: Steiling
authors.forename: Fabiola
authors.initials: F
authors.lastname: Dionisi
authors.forename: Elke
authors.initials: E
authors.lastname: Richling
mesh_terms: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism; D000818:Animals; D002726:Chlorogenic Acid / Q000737:chemistry / Q000378:metabolism*; D040503:Coffea / Q000737:chemistry; D003069:Coffee / Q000737:chemistry / Q000378:metabolism*; D004951:Esterification; D007887:Fabaceae / Q000737:chemistry; D005260:Female; D006801:Humans; D066298:In Vitro Techniques; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism; D007583:Jejunum / Q000378:metabolism; D008297:Male; D015394:Molecular Structure; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000378:metabolism; D059808:Polyphenols / Q000737:chemistry / Q000378:metabolism*; D011801:Quinic Acid / Q000737:chemistry / Q000378:metabolism; D034421:Sus scrofa
chemical_list: D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D002726:Chlorogenic Acid; D003069:Coffee; D000089762:Multidrug Resistance-Associated Protein 2; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D059808:Polyphenols; D011801:Quinic Acid; C000715087:ABCC2 protein, human
keywords: absorption; chlorogenic acids; coffee; dose response; transporters