Black tea extract and theaflavin derivatives affect the pharmacokinetics of rosuvastatin by modulating organic anion transporting polypeptide (OATP) 2B1 activity.

Theaflavins (TFs) are derived from black tea, an important source of dietary polyphenols. Although the potential interactions between dietary polyphenols and drugs have been demonstrated through in vitro and in vivo studies, little information is available concerning the influence of TFs on drug disposition. Organic anion transporting polypeptide 2B1 (OATP2B1) is expressed in human enterocytes and plays a role in the intestinal absorption of numerous drugs. The current study evaluated the effects of black tea extracts on the pharmacokinetics of rosuvastatin in rats, and investigated the effect of four major TFs (theaflavin, theaflavin-3-gallate, theaflavin-3'-gallate and theaflavin-3,3'-digallate) on the transport activity of OATP2B1. Black tea extracts significantly decreased the maximum plasma concentration (Cmax ) and area under the plasma concentration-time curve (AUC0 -8 ) of rosuvastatin by 48% and 37%, respectively (p < 0.001 and p < 0.01, respectively). Moreover, OATP2B1-mediated rosuvastatin and estrone-3-sulfate uptake was significantly reduced in the presence of TFs. A kinetic study revealed that the uptake efficiency (in terms of Vmax /Km ) of rosuvastatin was decreased following treatment with TFs. Black tea extracts also reduced OATP2B1-mediated rosuvastatin uptake. These results suggest that black tea reduces the plasma concentrations of rosuvastatin by inhibiting the intestinal OATP2B1-mediated transport of rosuvastatin.

Insulin stimulates transport of organic anion compounds mediated by organic anion transporting polypeptide 2B1 in the human intestinal cell line Caco-2.

Organic anion transporting polypeptide 2B1 (OATP2B1) is the major uptake transporter in the intestine, and transports various clinically used therapeutic agents. Insulin acts through the insulin receptor in targeted cells, and Rab8A is one of the insulin signaling pathways. The small intestine in humans also expresses insulin receptor and Rab8A. It has been reported that insulin stimulates peptide transporter 1 (PEPT1) expression at the apical membrane and increases uptake of PEPT1 substrates in small intestine epithelial model cells (Caco-2 cells). However, the effect of insulin on OATP2B1 in the small intestine has not been fully investigated. We found that Rab8A was associated with OATP2B1-mediated estrone-3-sulfate (E3S) uptake. Insulin stimulated the uptake of E3S by Caco-2 cells and the enhancement was sustained for 120 min. The Vmax value of E3S uptake significantly increased upon insulin exposure. Caco-2 cells treated with insulin showed increased OATP2B1 expression at the cell surface. The apical-to-basal transport of E3S was also increased by insulin. The increase of E3S transport was inhibited by the cold condition (4 °C) or the OATP2B1 inhibitor, taurocholate. These results indicate that insulin acts on the small intestine to increase OATP2B1-mediated absorption.

Organic anion-transporting polypeptide (OATP) 2B1 contributes to the cellular uptake of theaflavin.

Organic anion-transporting polypeptide (OATP) 2B1 has been reported in the apical membranes of the human small intestinal epithelium, where it contributes to the intestinal absorption of pharmacologically active drugs. To investigate the potential for OATP2B1-mediated drug-food interactions, the effects of several polyphenolic compounds on OATP2B1-mediated estrone-3-sulfate (E3S) transport were studied by using OATP2B1-expressing HEK293 cells. Our results showed that some compounds, especially theaflavin, were strong inhibitors of OATP2B1-mediated E3S uptake. Theaflavin showed a significantly higher uptake into the OATP2B1-expressing HEK293 cells than the control cells. The concentration dependence of the uptake of theaflavin was determined over a range of concentrations (0.5-100 µM) and the kinetic parameters (Km and Vmax) of theaflavin uptake were found to be 5.12 ± 0.67 µM and 41.6 ± 1.3 pmol/mg protein/min, respectively. The OATP2B1-mediated theaflavin uptake was inhibited by known OATP2B1 substrates such as E3S, bromsulphthalein (BSP), dehydroepiandrosterone-3-sulfate (DHEAS), and fluvastatin. Our results indicate that theaflavin is a novel substrate of OATP2B1. The results of this study might be helpful to predict the potential OATP2B1-mediated drug-theaflavin interactions and to avoid undesirable clinical consequences.

Characterization of loxoprofen transport in Caco-2 cells: the involvement of a proton-dependent transport system in the intestinal transport of loxoprofen.

Loxoprofen, a propionate non-steroidal anti-inflammatory drug (NSAID), is used widely in East Asian countries. However, little is known about the transport mechanisms contributing to its intestinal absorption. The objectives of this study were to characterize the intestinal transport of loxoprofen using the human intestinal Caco-2 cell model. The transport of loxoprofen was investigated in cellular uptake studies. The uptake of loxoprofen into Caco-2 cells was pH- and concentration-dependent, and was described by a Michaelis-Menten equation with passive diffusion (Km : 4.8 mm, Vmax : 142 nmol/mg protein/30 s, and Kd : 2.2 µl/mg protein/30 s). Moreover, the uptake of loxoprofen was inhibited by a typical monocarboxylate transporter (MCT) inhibitor as well as by various monocarboxylates. The uptake of [14 C] l-lactic acid, a typical MCT substrate, in Caco-2 cells was saturable with relatively high affinity for MCT. Because loxoprofen inhibited the uptake of [14 C] l-lactic acid in a noncompetitive manner, it was unlikely that loxoprofen uptake was mediated by high-affinity MCT(s). Our results suggest that transport of loxoprofen in Caco-2 cells is, at least in part, mediated by a proton-dependent transport system. Copyright © 2016 John Wiley & Sons, Ltd.