A Structure-Activity Relationship Study of Novel Hydroxamic Acid Inhibitors around the S1 Subsite of Human Aminopeptidase N.

Scammells, Peter J; Lee, Jisook; Drinkwater, Nyssa; McGowan, Sheena

Aminopeptidase N (APN/CD13) is a zinc-dependent ubiquitous transmembrane ectoenzyme that is widely present in different types of cells. APN is one of the most extensively studied metalloaminopeptidases as an anti-cancer target due to its significant role in the regulation of metastasis and angiogenesis. Previously we identified a potent and selective APN inhibitor, N-(2-(hydroxyamino)-2-oxo-1-(3',4',5'-trifluoro-[1,1'-biphenyl]-4-yl)ethyl)-4-(methylsulfonamido)benzamide (3). Herein, we report the further modifications performed to explore SAR around the S1 subsite of APN and to improve the physicochemical properties. A series of hydroxamic acid analogues were synthesised, and the pharmacological activities were evaluated in vitro. N-(1-(3'-fluoro-[1,1'-biphenyl]-4-yl)-2-(hydroxyamino)-2-oxoethyl)-4-(methylsulfonamido)benzamide (6f) was found to display an extremely potent inhibitory activity in sub-nanomolar range.