Synthesis, Biological Evaluation And Molecular Docking Studies Of3-(1,3-diphenyl-1H-pyrazol-4-yl)-N-phenylacrylamide Derivatives As Inhibitors Of HDAC Activity

Cancer is a serious threat to human health, clinical cure rate is very low. Almost all cancers are caused by abnormal cell proliferation, associated with the inactivation and mutation of cell cycle related genes, protein. On this basis, blocking abnormal cell proliferation is a kind of important means for the treatment of tumor. The acetylation and deacetylation of histone is one of key links for the regulation of gene expression, aberrant gene expression caused tumor, and also the reason for some genetic and metabolic disease. Histone acetylation is regulated by the enzyme (HAT) and HADH. In that case, the excessive expression of HDAC is raised by transcription factors, resulting in the inhibition of some particular genes, which can lead to cancer and other diseases.Experiments prove that HDAC inhibitors can increase the level of histone acetylation, leading to the activation and expression of specific genes, and accordingly, result in the differentiation of cell or apoptosis of cancer cells. Preliminary clinical studies have shown that humans can achieve high level of histone acetylation safely through the inhibition of the HDAC activity. Therefore, HDAC has become the latest and most popular target for the tumor drug research.There are many small molecules as HDAC inhibitors, among them, the amide class is the most important. MS275is a typical amide class of HDAC inhibitors in phase II clinical study. MS275exerts effects on HDAC active sites, forming the sandwich structure with the narrow activity pocket of Phe141and Phel98, thus blocking the extension of HDAC physiological substrates (Lys acetylated side chain at n-terminal) to the catalytic center. And cinnamic acid as a kind of hormones regulating plant growth and differentiation, have anti-inflammatory, antiplatelet aggregation, antitumor, and tyrosine kinase inhibition effects. Cinnamamide is built on the basis of the amide type of HDAC inhibitors with the introduction of double bond. The double bond of the composite structure, can form nucleophilic reaction with the amino acid residues, and on the other hand can stable key nuclear structure through the formation of conjugated carbonyl. Pyrazole, meanwhile, is a very important nitrogen heterocyclic molecule, exerting obvious anticancer, antibacterial, anti-inflammatory, antiviral effects and simultaneously accompanied by the characteristics of low toxicity. By inserting pyrazole group on the side of the N-phenyl cinnamamide, can improve the sensitivity of HDAC on the recognition surface of the parent nucleus, and thus enhance the specificity and affinity of the effect with HDAC.As stated above, with the help of computer aided drug design technology(Discovery Studio), we designed and synthesized16diaryl pyrazole cinnamon amides derivatives, and conduct the study of pharmacological activity screening and assessment of structure-activity relationship.In vitro, we have tested16compounds for two kinds of tumor cell lines (lung cancer cell A549and colon cancer cell HCT116), it was found that most of the compounds have potent antitumor activity with low toxicity. In comparison with A549, the inhibitory of target compounds against HCT116inhibitory effect is more obvious. Among the compounds, compound8c showed the most potent biological activity with the IC50value of0.62±0.02for HCT116. In order to explore the antitumor mechanism, the target compounds were evaluated for HDAC-1and HDAC-2inhibition, in consistent of the results of tumor cell antiproliferation,8c showed the most potent biological activity against HDAC-1(IC50of0.42±0.02μM), demonstrating that compound8c may be a potential anticancer agent against HCT116cancer cell. Meanwhile, the results of Western blot also provided a theoretical basis and further confirmed that our experimental results, proving that the synthesized16 compounds may exert anticancer effects through inhibition of the HDAC activity.