Synthesis Of Novel Amber Lactam Derivatives As Aminopeptidase N Inhibitors And Preliminary Study On Their Activities In Vitro

Aminopeptidase N (APN), also known as CD13, is a membrane-bound zinc-dependent exopeptidase. It’s widely distributed in various tissues with high levels, such as intestine, kidney, liver and central nervous system. APN plays an important role in tumor progression by regulating processes such as tumor invasion and metastasis. As APN can degrade extracellular matrix (ECM), which would help to tumor cells invading the basement membrane and matrix, penetrating the vessel wall, tumor cells can proliferate and metastasize quickly. In addition, APN can promote tumor angiogenesis as a regulator of new blood vessels of the tumor.It was reported that APN is a viral receptor for human coronavirus229E (HCoV-229E), porcine transmissible gastroenteritis virus (TGEV), human cytomegalovirus (HCMV). Inhibition of APN can effectively decrease the growth of tumor cells and regulate the body’s immune system. Therefore, APN has been implicated as a novel therapeutic target for Anti-virus and cancer treatment.In this paper, based on the summary of structural features of APN inhibitors (Natural product:Bestatin) and three-dimensional structural of APN active site, we designed some novel structural APN inhibitors by computer-aided drug design technology and then11compounds were synthesized.It is worthy of note that the Benzothiazole is key to the parent ring in the series of products. It has been reported that the Benzothiazole and its derivatives have high anti-tumor activity, especially2-benzothiazole. The target compounds were synthesized by the process of cyclization, acidylation, hydrolyzation and acidylation followed by2-benzothiazole. Eleven novel Amber lactam derivatives were synthesized and their structures were confirmed by IR、1H-NMR、ESI-MS.Finally, the inhibitory activities of these compounds to K562and. ES-2cells were measured by MTT assay in vitro. Then the values of IC50for these compounds were obtained. The results suggested that the compound (5f)(2,3-dihydroxy-N1-(6-methoxybenzo[d]thiazol-2-yl)-N4-(p-tolyl) succinamide) had highest activity against ES-2(IC50=1.12μM), which was closed to that of Bestatin (IC50=0.98μM). Whereas, all compounds were shown low activities against K562. Furthermore, inhibitory activities against APN by these compounds were determined using L-leucyl-p-nitroaniline as the substrate. Our results indicated that the compound5D (2,3-dihydroxy-N1-(6-methoxybenzo[d]thiazol-2-yl)-N4-(4-methoxyphenyl) succinamide) and5F had higher inhibitory activities against APN. The structure of two compounds have-OCH3substituent group instead of-H in para-position of2-benzothiazole. Combined with the results of inhibition of cells in vitro, the2-Benzothiazole with-OCH3substituent group in para-position showed highest anti-tumor activity.In summary, a potentially good anti-tumor activity compound were designed, sysnthesized and screened preliminarily in vitro in this paper, which would provide new insight and approach for the synthesis of novel inhibitor of aminopeptidase N.