In vitro and in vivo evaluation of organic anion-transporting polypeptide 2B1-mediated pharmacokinetic interactions by apple polyphenols.

Organic anion-transporting polypeptide (OATP) 2B1 plays a critical role in the intestinal absorption of substrate drugs. Apple juice reportedly interacts with OATP2B1 substrate drugs. The purpose of this study was to investigate the effect of two apple polyphenols, phloretin and phloridzin, on OATP2B1-mediated substrate transport in vitro and to evaluate the effect of phloretin on rosuvastatin pharmacokinetics in rats.In vitro studies revealed that both polyphenols inhibited OATP2B1-mediated uptake of estrone-3-sulfate. Despite preincubation with phloretin and subsequent washing, the inhibitory effect was retained. Phloretin markedly decreased OATP2B1-mediated rosuvastatin uptake, with an IC50 value of 3.6 µM.On coadministering rosuvastatin and phloretin in rats, the plasma concentration of rosuvastatin 10 min after oral administration was significantly lower than that in the vehicle group. The area under the plasma concentration-time curve of rosuvastatin was not significant, showing a tendency to decrease in the phloretin group when compared with the vehicle group. The in-situ rat intestinal loop study revealed the inhibitory effect of phloretin on rosuvastatin absorption.Phloretin has potent and long-lasting inhibitory effects on OATP2B1 in vitro. Phloretin may inhibit OATP2B1-mediated intestinal absorption of rosuvastatin; however, it failed to significantly impact the systemic exposure of rosuvastatin in rats.

Characterization of deoxyribonucleoside transport mediated by concentrative nucleoside transporters.

Human concentrative nucleoside transporters (CNTs) are responsible for cellular uptake of ribonucleosides; however, although it is important to better characterize CNT-subtype specificity to understand the systemic disposition of deoxyribonucleosides (dNs) and their analogs, the involvement of CNTs in transporting dNs is not fully understood. In this study, using COS-7 cells that transiently expressed CNT1, CNT2, or CNT3, we investigated if CNTs could transport not only ribonucleosides but also dNs, i.e., 2'-deoxyadenosine (dAdo), 2'-deoxyguanosine (dGuo), and 2'-deoxycytidine (dCyd). The cellular uptake study demonstrated that dAdo and dGuo were taken up by CNT2 but not by CNT1. Although dCyd was taken up by CNT1, no significant uptake was detected in COS-7 cells expressing CNT2. Similarly, these dNs were transported by CNT3. The apparent Km values of their uptake were as follows: CNT1, Km ＝ 141 µM for dCyd; CNT2, Km ＝ 62.4 µM and 54.9 µM for dAdo and dGuo, respectively; CNT3, Km ＝ 14.7 µM and 34.4 µM for dGuo and dCyd, respectively. These results demonstrate that CNTs contribute not only to ribonucleoside transport but also to the transport of dNs. Moreover, our data indicated that CNT1 and CNT2 selectively transported pyrimidine and purine dNs, respectively, and CNT3 was shown to transport both pyrimidine and purine dNs.