N-(Methyloxycarbonyl)thiophene sulfonamides as high affinity AT2 receptor ligands.

A series of meta-substituted acetophenone derivatives, encompassing N-(alkyloxycarbonyl)thiophene sulfonamide fragments have been synthesized. Several selective AT2 receptor ligands were identified, among those a tert-butylimidazole derivative (20) with a K of 9.3 nM, that demonstrates a high stability in human liver microsomes (t = 62 min) and in human hepatocytes (t = 194 min). This methyloxycarbonylthiophene sulfonamide is a 20-fold more potent binder to the AT2 receptor and is considerably more stable in human liver microsomes, than a previously reported and broadly studied structurally related ATR prototype antagonist 3 (C38). Ligand 20 acts as an ATR agonist and caused an ATR mediated concentration-dependent vasorelaxation of pre-contracted mouse aorta. Furthermore, in contrast to imidazole derivative C38, the tert-butylimidazole derivative 20 is a poor inhibitor of CYP3A4, CYP2D6 and CYP2C9. It is demonstrated herein that smaller alkyloxycarbonyl groups make the ligands in this series of ATR selective compounds less prone to degradation and that a high AT2 receptor affinity can be retained after truncation of the alkyloxycarbonyl group. Binding modes of the most potent ATR ligands were explored by docking calculations combined with molecular dynamics simulations.