Transepithelial Transport of Theasinensins through Caco‑2 Cell Monolayers and Their Absorption in Sprague–Dawley Rats after Oral Administration

Abstract

The aim of this study is to illustrate the <i>in vivo</i> and <i>in vitro</i> absorption of theasinensins B and A that are (−)-epigallocatechin-3-<i>O</i>-gallate (EGCG)–(−)-epigallocatechin (EGC) dimer and EGCG dimer, respectively, and their transport pathway across the intestinal membrane. Our animal study by a single oral administration to rats demonstrated the intact absorption of theasinensins into the blood system, which was estimated to be a >10-fold lower absorption amount than EGCG. The <i>in vitro</i> absorption study indicated that theasinensins can be transported across Caco-2 cell monolayers, while their permeability coefficients were also >10-fold lower than those of EGCG and EGC. Transport experiments using cytochalasin D or quercetin as a tight junction (TJ) modulator and a non-saturable permeation revealed that theasinensins were transported across Caco-2 cells in a TJ paracellular diffusion route. In conclusion, the dimers of condensed catechins, theasinensins B and A, can be absorbed intact into rat blood and transported across Caco-2 cell monolayers probably through a TJ paracellular pathway