Organic cation transporter
1 (OCT1) plays a critical role in the
hepatocellular uptake of structurally diverse endogenous compounds
and xenobiotics. Here we identified competitive and noncompetitive
OCT1-interacting ligands in a library of 1780 prescription drugs by
combining in silico and in vitro methods. Ligands were predicted by
docking against a comparative model based on a eukaryotic homologue.
In parallel, high-throughput screening (HTS) was conducted using the
fluorescent probe substrate ASP+ in cells overexpressing
human OCT1. Thirty competitive OCT1 ligands, defined as ligands predicted
in silico as well as found by HTS, were identified. Of the 167 ligands
identified by HTS, five were predicted to potentially cause clinical
drug interactions. Finally, virtual screening of 29 332 metabolites
predicted 146 competitive OCT1 ligands, of which an endogenous neurotoxin,
1-benzyl-1,2,3,4-tetrahydroisoquinoline, was experimentally validated.
In conclusion, by combining docking and in vitro HTS, competitive
and noncompetitive ligands of OCT1 can be predicted.