Studies On The Interactions Between Fluorescent Substrates And Flavonoids Mediated By Human Hepatic OATPs

Organic anion transporting polypeptides(OATPs)2B1 and 1B1 are two important transporters involved in liver uptake and mediate the uptake of many endogenous substances such as steroids and exogenous substances such as drugs from blood into hepatocytes.The liver is an important organ for drug metabolism and thus these uptake transporters also play important roles in drug metabolism.Therefore,the occurrence of many drug-drug interactions is associated with OATPs.The purpose of this study is to identify and investigate the potential modulators of OATP1B1 and 2B1 from naturally occurring flavanols,flavonols,flavones,and isoflavones by high-throughput screening methods using fluorescent substrates.In this study,Chinese hamster ovary cells(CHO)stably expressing OATP1B1 and 2B1(CHO-OATP1B1 and CHO-OATP2B1)were used and an inhibitor screening assay using fluorescent compounds as substrates has been established.We measured the effect of 23 common flavonoid compounds on OATP1B1-mediated 2',7'-dichlorofluorescein(DCF)uptake and OATP2B1-mediated 4',5'-dibromofluorescein(DBF)uptake in 24-well plates.Our results showed that various flavonoid compounds had inhibitory effect on OATP1B1-mediated DCF transport and OATP2B1-mediated DBF transport.Among them,luteolin,quercetin,and fisetin have the strongest inhibitory effect on DCF transport with IC50 values being of 0.8±1.2,2.4 ± 1.2,and 3.5 ± 1.2 ?M,respectively;Scutellarin,myricetin,and luteolin have the strongest inhibitory effect on DBF transport with ICso values being of 0.1 ± 1.1,3.4 ± 1.6 and 3.9 ± 1.6 ?M,respectively.By analyzing the structure of these compounds,it is found that the substituents at position 3 of ring C of the 2-phenyl-1,4-benzopyrone backbone have great impact on their inhibitory potency.These compounds are more potent than their corresponding glycosides,and the type and length of sugar moiety have impact on their inhibitory effect.The aim of this paper is to use fluorescent substrates which could be used in high-throughput screening to study the effects of natural products or other drugs on the transport mediated by OATP1B1 and 2B1,and thus to effectively predict and avoid potential OATPs-mediated drugs-drug and food-drug interactions.Therefore,this study might provide valid experimental basis and reference for new drug research and development and medication safety in clinic.