The Design, Synthesis And Preliminary Activity Assay In Vitro Of AHPA Derivatives As APN Inhibitors

Aminopeptidases N, one of membrane-bound zinc-dependent exopeptidase, is expressed in many tissues including intestine, kidney, liver as well as the central nervous system . The enzyme is involved in the final hydrolysis of nutrients and the degradation of bioactive molecules such as enkaphalin and endorphin. Furthermore, APN serves as a receptor for corona viruses, and it is involved in processes of antigen presentation. More importantly, Saiko and coworkers have shown that the CD13 antigen is involved in the regulation of tumour-cell invasion and the degradation of extracellular matrix.All these findings make this enzyme an interesting target for possible anti-tumor drugs research, which require the development of potent and more selective inhibitors.Based on the 3D structures and binding models of some novel APN inhibitors in complex with APN, one series of AHPA derivatives are designed with the aid of Symble Program. All compounds are synthesized starting from the substitution reaction of l-(2-bromoethyl)benzene to form the basic scaffold, followed by the addition reaction with glyoxylic acid and the key intermediate NO₂-AHPA was obtained. The intermediate compound is condensed with different amino acids and then reducted to produce the target compounds. The chemical structures of target compounds are identified by IR, ESI-MS and NMR (¹H-NMR and ¹³C-NMR) spectra.Preliminary bioactivity assays are carried out in vitro. Inhibitory activity of compounds against APN is measured with L-leucine p-nitroanilide as substrate. Asa result, most of these newly synthesized compounds show good inhibitory activity on APN, and compound ZX3s ZX4 and ZX6 are the excellent inhibitors with IC50 values of 0.51 > 0.57 and 2.18 u M respectively, in contrast with the positive drug Bestatin, which IC50 value is 25.01 u M. Structure-activity relationships of twenty tested compounds are elucidated and compounds containing lipoid side chain substituents have higher activity than aromatic heterocyclic substituents; compounds with different configuration have different inhibiting activity.In this thesis, APN inhibitors of AHPA derivatives have good inhibiting activity on APN in vitro. Some of these compounds, for example ZX3> ZX4 and ZX6, are supposed to have potential anti-tumor activity in vivo and might be promising lead compounds.