Hypothetical inhibition mechanism of novel urea transporter B inhibitor

This study was designed to develop hypothetical inhibition mechanism of novel UT-B inhibitor and exploit novel compounds with UT-B inhibitory activity and to obtain promising lead compounds. We integrated cell based high throughput screening and in silico method to identify an undiscovered UT-B inhibitor binding site and proposed the mechanism of UT-B inhibitor in cross-species. We employed high-throughput screening using an erythrocyte os- motic lysis assay and identified 4 compounds PU21, PU168, PU468 and PU474 with UT-B inhibitory activity in vitro from 2319 hits. 16 compounds with UT-B inhibitory activity were screened by erythrocyte osmotic lysis assay from 60 analogues of PU21. PU14, one of 16 compounds exhibited potential inhibition activity in human, rabbit, rat, mouse in vitro and pharmacological diuresis activity in vivo. Based on the physiological data, we built a compu- tational mode of human UT-B by homology modeling. The putative UT-B binding site was identified by structure- based drug design and validated by ligand-based and QSAR model. Additionally, UT-B structural and functional differences under inhibitors treated and untreated conditions were simulated by Molecular Dynamics （MD）. The UT-B inhibitor binding site analysis and validation provide structure basses for lead identification and optimization.