Theaflavins, dimeric catechins, inhibit peptide transport across Caco-2 cell monolayers via down-regulation of AMP-activated protein kinase-mediated peptide transporter PEPT1.

Junko Takeda, Ha-Young Park, Yuri Kunitake, Keiko Yoshiura, Toshiro Matsui

Index: Food Chem. 138(4) , 2140-5, (2013)

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Abstract

In the small intestine, peptide transporter 1 (PEPT1) plays a role in the transport of di- and tripeptides. In this study, we investigated whether theaflavins (TFs) affect the absorption of small peptides in human intestinal Caco-2 cells, since TFs do not penetrate through the cells and might be involved in intestinal transport systems. In transport experiments, the transport of glycyl-sarcosine (Gly-Sar, a model molecule for PEPT1 transport) and other dipeptides (Val-Tyr and Ile-Phe) were significantly reduced (P<0.05) in TFs-pretreated cells. In TF 3'-O-gallate-pretreated cells, Western blot analysis revealed attenuated expression of PEPT1 transporter and Gly-Sar transport was completely ameliorated by 10 μM Compound C, an AMP-activated protein kinase (AMPK) inhibitor. In conclusion, the present study demonstrated that TFs inhibit peptide transport across Caco-2 cell monolayers, probably through suppression of AMPK-mediated PEPT1 expression, which should be considered a new bioactivity of TFs in black tea.Copyright © 2012 Elsevier Ltd. All rights reserved.