Design and synthesis of novel sulfanilamide derivatives as aminopeptidase N inhibitors

Guided by the structural architecture of the aminopeptidase N (APN) active site, we designed and synthesized a series of novel APN inhibitors featuring sulfanilamide scaffold coupled with hydroxamate zinc-binding motifs. Among the series, compound 2k exhibited the inhibitory activity (IC₅₀ = 4.3 μM) as effectively as a positive control drug Bestatin. Notably, our compounds exhibited pronounced selectivity against zinc-dependent metallopeptidase MMP-2. The SAR research indicated that ortho-disubstitution in the phenyl group could lead to an order of magnitude improvement. A molecular docking study validated the novel binding mode of compound 2k. The predicted ADME properties highlighted the improved hydrophilicity, cell permeability, and human oral absorption of 2k than that of bestatin. These results validated simultaneously occupying S1’ and S2’ pockets as a viable design strategy for discovering APN inhibitors with a non-canonical binding modality. We anticipate that compound 2k with high selectivity will be harnessed as a structurally distinctive probe candidate to investigate the pathophysiological roles of APN in tumor angiogenesis and metastasis.