title: Identification of natural products as modulators of OATP2B1 using LC-MS/MS to quantify OATP-mediated uptake.
abstract: BACKGROUND
  Organic anion-transporting polypeptide 2B1 (OATP2B1) which is highly expressed in enterocytes and hepatocytes could be a key determinant for the intestinal absorption and hepatic uptake of its substrate drugs. Natural products are commonly used in traditional Chinese medicine, foods, and beverages.
  
  
  OBJECTIVE
  The objective of this study is to determine the OATP2B1-mediated drug interactions that could occur between natural products and OATP2B1 substrate drugs.
  
  
  METHODS
  Human OATP2B1 was transiently expressed in human embryonic kidney (HEK293) cells and characterized by immunofluorescence, Western blot, and uptake assay. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods for detecting OATP2B1 substrates estrone-3-sulfate (E3S) and three statins had been developed and were employed to investigate the effects of 27 frequently used natural products on the function of OATP2B1. Uptake of 5 μM E3S and 1 μM statins in the absence or presence of natural products was measured at 37 °C for 2 min with empty vector- and OATP2B1-transfected HEK293 cells. The IC50 values of inhibitors for OATP2B1-mediated 5 μM E3S uptake were determined.
  
  
  RESULTS
  Our results showed that mulberrin, scutellarin, quercetin, and glycyrrhetinic acid were strong inhibitors of OATP2B1-mediate E3S uptake with IC50 values being 1.8, 2.0, 7.5, and 13.0 μM, which were comparable with their plasma concentrations in clinical trials. They also inhibited OATP-mediated uptake of atorvastatin, fluvastatin, and rosuvastatin. These results indicated that clinically relevant drug interactions could occur between these natural compounds and OATP2B1 substrate drugs.
  
  
  CONCLUSIONS
  The information obtained from this study might be helpful to predict and to avoid potential OATP2B1-mediated drug interactions.
authors: a Department of Pharmacy , College of Pharmaceutical Sciences, Soochow University , Suzhou , China.
authors: Fengjiao
authors: F
authors: Wen
authors: a Department of Pharmacy , College of Pharmaceutical Sciences, Soochow University , Suzhou , China.
authors: Meizhi
authors: M
authors: Shi
authors: a Department of Pharmacy , College of Pharmaceutical Sciences, Soochow University , Suzhou , China.
authors: Jialin
authors: J
authors: Bian
authors: a Department of Pharmacy , College of Pharmaceutical Sciences, Soochow University , Suzhou , China.
authors: Hongjian
authors: H
authors: Zhang
authors: a Department of Pharmacy , College of Pharmaceutical Sciences, Soochow University , Suzhou , China.
authors: Chunshan
authors: C
authors: Gui
mesh_terms: D001688:Biological Products / Q000494:pharmacology*; D015153:Blotting, Western; D002853:Chromatography, Liquid; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D004970:Estrone / Q000031:analogs & derivatives* / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D057809:HEK293 Cells; D041743:Herb-Drug Interactions; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000378:metabolism*; D027361:Organic Anion Transporters / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D053719:Tandem Mass Spectrometry; D014162:Transfection
chemical_list: D001688:Biological Products; D004365:Drugs, Chinese Herbal; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D027361:Organic Anion Transporters; C450859:SLCO2B1 protein, human; D004970:Estrone; C017296:estrone sulfate
keywords: ADME; HEK293; drug interactions; solute carrier; transporter