1,1-Difluoroethyl-substituted triazolothienopyrimidines as inhibitors of a human
urea transport protein (UT-B): new analogs and binding model.
Bioorg Med Chem Lett 2013;
23:3338-41. [PMID:
23597791 PMCID:
PMC3954708 DOI:
10.1016/j.bmcl.2013.03.089]
[Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2013] [Revised: 03/21/2013] [Accepted: 03/22/2013] [Indexed: 11/28/2022]
Abstract
The kidney urea transport protein UT-B is an attractive target for the development of small-molecule inhibitors with a novel diuretic ('urearetic') action. Previously, two compounds in the triazolothienopyrimidine scaffold (1a and 1c) were reported as UT-B inhibitors. Compound 1c incorporates a 1,1-difluoroethyl group, which affords improved microsomal stability when compared to the corresponding ethyl-substituted compound 1a. Here, a small focused library (4a-4f) was developed around lead inhibitor 1c to investigate the requirement of an amidine-linked thiophene in the inhibitor scaffold. Two compounds (4a and 4b) with nanomolar inhibitory potency (IC50≈40 nM) were synthesized. Computational docking of lead structure 1c and 4a-4f into a homology model of the UT-B cytoplasmic surface suggested binding with the core heterocycle buried deep into the hydrophobic pore region of the protein.
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