Design, Synthesis And Preliminary Activity Study Of Chloramphenicol Amine Derivatives As Potent APN Inhibitors

Aminopeptidase N (APN/CD13) is a Zn2+-dependent transmembrane metalloprotease, belonging to clan MA, family M1. It mainly comprises three parts, viz. N-terminal cytoplastic part, transmembrane part, C-terminal catalytic part. Physiologically, APN exists in the form of dimers on the surface of cellular membranes widely distributing in different human tissues and systems. Notably, it overexpresses on malignant tumor cells’ membranes of variety, like HL-60cell, ES-2cell. APN shows efficient proteolytic activity, making it important in tumorigensis and cancer development. Thus, APN has become one of the hot targets for developing anti-caner agents recently.Much attention has been paid to the development of APN inhibitors. Bestatin, the first drug targetting APN marketed in1976, is still in clinical use for improving human immunologic functions. Other natural inhibitors have also been identified. Meanwhile, chemically synthesized inhibitors like β-amino thioalcohol, a-amino phosphate have also been available. For several continuous years’ research into the development of APN inhibitors, our lab has also reported lots of potential APN inhibitors for these years.Based on the highly homology of human APN and E. Coli APN, we have adopted the crystal structure of eAPN and its binding mode of Bestatin as the initial study model to successfully obtain compounds sharing2,3-diamino-l-(4-nitrophenyl) propan-1-ol (DANP) scaffold depending on the computer aided drug design (CADD). (1S,2S)2-Amino-l-(4-nitrophenyl) propane-1,3-diol (ANP) was used as the starting material to synthesize target compounds taking the following steps, viz. N-Boc protection reacion, Bromination reaction, Azidation reaction, and reduction reaction to get the key intermediate N-Boc DANP. Alternately, hydroxyl group would be transferred directly applying one-pot strategy. Subsequently, peptidomimetics were synthesized via classic HOBt/EDCI peptide condensation reaction. Furthermore, the nitrol group was subtituted to exame the role of electronic effect. Chemical structures of compounds were identified using1H-NMR, ESI-MS, HRMS and so on. Preliminary biological activity of these compounds was tested through enzymatic assay, transwell assay and so on.In this project, we overall obtained30small molecullar APN inhibitors with novel structures and most of them show moderate APN inhibitory activities in vitro. Among them, the IC50values of compounds91,9r,10e against APN were lower than10μM, which was in the same level of positive control Bestatin (IC50=3.7±0.4μM). Dipeptide peptidomemetics generally exhibit worse activity than tripeptide peptidomemetics possibly contributing to poorer affinities to APN with shorter side chains. Substitution of nitrol group showed no remarkable change in activity, implying that electronic effects are not the determing factor of compounds’activity here. Compounds9c,9r,10e were all observed to inhibit the invasion of tumor cells remarkably and compounds91,10e showed considerable anti-angiogenisis effects in vitro, too. Finally,3D-QSAR model with good predictability was constructed based on experimental data available.In this project, chloramphenicol amine derivatives sharing DANP scaffold were successfully designed and synthesized, most of which showing moderate APN inhibitory efficacy. Also, the3D-QSAR model constructed will definitely benefit a lot in the future study of compounds with similar structures.