Design, Synthesis, and Biological Evaluation of Pyrazoline-Based Hydroxamic Acid Derivatives as AminopeptidaseN (APN) Inhibitors

AminopeptidaseN (APN) has been recognized as a target for anticancer treatment due to its overexpression on diverse malignant tumor cells and association with cancer invasion, metastasis and angiogenesis. Herein we describe the synthesis, biological evaluation, and structure-activity relationship study of two new series of pyrazoline analogues as APN inhibitors. Among these compounds, 5-(2-(2-(hydroxyamino)-2-oxoethoxy)phenyl)-3-phenyl-4,5-dihydro-1H-pyrazole-1-carboxamide (compound 13e) showed the best APN inhibition with an IC50 value of 0.16 +/- 0.02m, which is more than one order of magnitude lower than that of bestatin (IC50=9.4 +/- 0.5m). Moreover, compound 13e was found to inhibit the proliferation of diverse carcinoma cells and to show potent anti-angiogenesis activity. At the same concentration, compound 13e presents significantly higher anti-angiogenesis activity than bestatin in human umbilical vein endothelial cells (HUVECs) capillary tube formation assays. The putative binding mode of 13e in the active site of APN is also discussed.