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  • Flavonoids are inhibitors of human organic anion transporter 1 (OAT1)-mediated transport.

Flavonoids are inhibitors of human organic anion transporter 1 (OAT1)-mediated transport.

Drug metabolism and disposition: the biological fate of chemicals (2014-07-09)
Guohua An, Xiaodong Wang, Marilyn E Morris
ABSTRACT

Organic anion transporter 1 (OAT1) has been reported to be involved in the nephrotoxicity of many anionic xenobiotics. As current clinically used OAT1 inhibitors are often associated with safety issues, identifying potent OAT1 inhibitors with little toxicity is of great value in reducing OAT1-mediated drug nephrotoxicity. Flavonoids are a class of polyphenolic compounds with exceptional safety records. Our objective was to evaluate the effects of 18 naturally occurring flavonoids, and some of their glycosides, on the uptake of para-aminohippuric acid (PAH) in both OAT1-expressing and OAT1-negative LLC-PK1 cells. Most flavonoid aglycones produced substantial decreases in PAH uptake in OAT1-expressing cells. Among the flavonoids screened, fisetin, luteolin, morin, and quercetin exhibited the strongest effect and produced complete inhibition of OAT1-mediated PAH uptake at a concentration of 50 μM. Further concentration-dependent studies revealed that both morin and luteolin are potent OAT1 inhibitors, with IC50 values of <0.3 and 0.47 μM, respectively. In contrast to the tested flavonoid aglycones, all flavonoid glycosides had negligible or small effects on OAT1. In addition, the role of OAT1 in the uptake of fisetin, luteolin, morin, and quercetin was investigated and fisetin was found to be a substrate of OAT1. Taken together, our results indicate that flavonoids are a novel class of OAT1 modulators. Considering the high consumption of flavonoids in the diet and in herbal products, OAT1-mediated flavonoid-drug interactions may be clinically relevant. Further investigation is warranted to evaluate the nephroprotective role of flavonoids in relation to drug-induced nephrotoxicity mediated by the OAT1 pathway.

MATERIALS
Product Number
Brand
Product Description

Supelco
Chrysin, analytical standard
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Ascorbic Acid, Pharmaceutical Secondary Standard; Certified Reference Material
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Chrysin, ≥96.5%
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Luteolin, analytical standard
USP
Ascorbic acid, United States Pharmacopeia (USP) Reference Standard
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Formic acid solution, BioUltra, 1.0 M in H2O
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Formic acid, ≥95%, FCC, FG
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Luteolin, ≥98% (TLC), powder
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Phloretin, ≥99%
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Myricetin, ≥96.0%, crystalline
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(−)-Epigallocatechin gallate, ≥80% (HPLC), from green tea
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(−)-Epigallocatechin gallate, ≥95%
Ascorbic acid, European Pharmacopoeia (EP) Reference Standard
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Epigallocatechin gallate, primary reference standard
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Probenecid, United States Pharmacopeia (USP) Reference Standard
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Formic acid, ACS reagent, ≥88%
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Formic acid, ACS reagent, ≥96%
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Formic acid, reagent grade, ≥95%
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L-Ascorbic acid, FCC, FG
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L-Ascorbic acid, certified reference material, TraceCERT®, Manufactured by: Sigma-Aldrich Production GmbH, Switzerland
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