Benzotropolone moiety in theaflavins is responsible for inhibiting peptide-transport and activating AMP-activated protein kinase in Caco-2 cells | Functional Foods in Health and Disease - Online ISSN: 2160-3855; Print ISSN: 2378-7007 Skip to main content Skip to main navigation menu Skip to site footer Open Menu Functional Foods in Health and Disease - Online ISSN: 2160-3855; Print ISSN: 2378-7007 Home Food Science Publisher Functional Food Center Current Archives About About the Journal Aims and Scope Contact Editing Services Editorial Team Express Peer Review Graphical Abstract Journal Insights Privacy Statement Submissions Announcements Search Search Register Login Home / Archives / Vol. 3 No. 5 (2013): May 2013 / Research Articles Benzotropolone moiety in theaflavins is responsible for inhibiting peptide-transport and activating AMP-activated protein kinase in Caco-2 cells Authors Ha-Young Park Department of Bioscience and Biotechnology, Division of Bioresources and Biosciences, Faculty of Agriculture, Graduate School of Kyushu University, 6-10-1 Hakozaki, Fukuoka, 812-8581 Yuri Kunitake Department of Bioscience and Biotechnology, Division of Bioresources and Biosciences, Faculty of Agriculture, Graduate School of Kyushu University, 6-10-1 Hakozaki, Fukuoka, 812-8581 Toshiro Matsui Department of Bioscience and Biotechnology, Division of Bioresources and Biosciences, Faculty of Agriculture, Graduate School of Kyushu University, 6-10-1 Hakozaki, Fukuoka, 812-8581 DOI: https://doi.org/10.31989/ffhd.v3i5.60 Abstract Objective: In the small intestine, peptide transporter 1 (PEPT1) plays a role in the transport of di- and tri-peptides. Recently, we found that theaflavins (TFs), dimeric catechins, inhibited the transport of di-peptides across Caco-2 monolayers by suppressing the expression of PEPT1 through AMP-activated protein kinase (AMPK) activation. In this study, we investigated the structural requirement of theaflavins for the effect, and the mechanism(s) underling theaflavin-induced AMPK activation. Methods: Theaflavin-3’-O-gallate (TF3’G) was used for this study, since it possessed the most potent inhibition power for peptide-transport among theaflavins. Absorption ability was measured with Caco-2 cell monolayers treated with or without 20 μM sample (TF3’G or its related compounds) in an Ussing Chamber. The amount of Gly-Sar (a model of PEPT1-transporing peptide) transport at fixed time-points to 60 min was determined by fluorescent naphthalene-2,3-dicarboxaldehyde-derivatized assay (Ex/Em: 405 nm/460 nm). The apparent permeability coefficient (Papp) was used to evaluate the permeability. Expression of PEPT1 protein in Caco-2 cells treated with or without 20 μM TF3’G in the presence or absence of inhibitor (10 μM compound C as AMPK inhibitor or 25 μM STO-609 as CaMKK inhibitor) was evaluated by Western blot. Results: The Papp value of Gly-Sar significantly (P < 0.05) decreased in 20 μM purprogallin-treated Caco-2 cells as well as in TF3’G-treated cells, together with the reduction of PEPT1 expression, while their monomeric catechins did not show any Papp reduction. In TF3'G-treated Caco-2 cells, the recovery of the reduced PEPT1 expression was found by 10 μM compound C, but not STO-609. Conclusion: The study demonstrated that the benzotropolone moiety in theaflavins was a crucial structural requirement for exerting the inhibition of intestinal peptide-transport, and the suppression of PEPT1 expression by theaflavins would be caused by activating LKB1/AMPK pathway, but not CaMKK/AMPK pathway. Keywords: Theaflavin-3’-Ο-gallate, Peptide transport, PEPT1, Benzotropolone, AMP-activated protein kinase, Calmodulin-dependent protein kinase kinase   Downloads [Abstract] [Full Article] Published 2013-05-24 Issue Vol. 3 No. 5 (2013): May 2013 Section Research Articles License Authors retain the copyright of their articles and grant the Functional Food Center (FFC) and its journals the right of first publication under the terms of the Creative Commons Attribution 4.0 International License. This license permits unrestricted use, distribution, and reproduction in any medium, including commercial use, provided the original author(s) and source are properly credited. Authors may post and share their published work freely, provided that the original publication in this journal is acknowledged. By submitting to this journal, authors confirm that their manuscripts are original, not under consideration elsewhere, and that they hold the necessary rights to grant this license. The Functional Food Center encourages open scientific exchange and allows derivative and extended works, provided attribution to the original publication is maintained. About the Journal      Editing Services      Graphical Abstract      Journal Insights        Submissions        Editorial Team       Privacy Statement        Contact        Current        Archives   Open Journal Systems Hosting and Support by: OpenJournalSystems.com