Design,synthesis And Anti-tumor Activity Evaluation Of Novel 1,3-diaryl-1,2,4-triazole HDAC6 Inhibitors

Histone lysine deacetylase 6（HDAC6）,as a key enzyme for epigenetic regulation,can deacetylate histones and a variety of non-histone substrates.Studies have found that HDAC6 is highly expressed in a variety of tumor cells,and inhibiting its activity can effectively block tumorigenesis and development.The development of HDAC6inhibitors with high specificity,low toxicity and good pharmacokinetic properties is of great significance for tumor treatment.In this project,with the help of HDAC6 inhibitor screening platform and activity screening of structurally diverse small molecule compound library built by the research group,a lead compound 1 with potential HDAC6 inhibition effect was found.Based on a structure-based drug design method,a series of novel 1,3-diaryl-1,2,4-triazole derivatives were designed and synthesized.and their structure-activity relationships were analyzed;Meanwhile,gastric cancer MGC-803 cells with high expression of HDAC6 were used as the research object to further verify the inhibitory effect of the target compound targeting HDAC6 in the cell and evaluate its anti-tumor activity.The specific contents of the research work are as follows:First,through systematic literature research,I had mastered the structure and function of HDAC6 protein,its catalytic mechanism,and its relationship with various cancers.The latest research progress of HDAC6 inhibitors and the main problems to be solved in the development of HDAC6 inhibitors are discussed,which provides solid theoretical guidance for the smooth development of this topic.Second,the 1,2,4-triazole structural unit exists in the structure of many marketed drugs and has a wide range of biological functions.In the early stage of this project,relying on the HDAC6 inhibitor screening platform,the activity screen of the small molecule compound library of the internal structure of the research group was conducted,and the lead compound 1（including 1,2,4-triazole structural unit）with potential HDAC6 inhibitory effect was found.;In the meantime,literature research found that most of the reported HDAC6 inhibitors contain amide structural units in the Cap region.In view of the above findings,on the basis of compound 1,we designed and synthesized a series of bio-isosteres 1,2,4-triazole group of amide as Cap area,phenyl as Linker area,and amide,ester,carboxylic acid and hydroxamic acid as ZBG.1,3-Diaryl-1,2,4-triazole derivative.Third,all the designed and synthesized compounds have been evaluated for HDAC6inhibitory activity.The results show that the modification of the phenyl group at the N-1 position of 1,2,4-triazole will result in greatly reduced activity and poor selectivity;The phenyl modification at position C-3 shows better functional group tolerance,while the substitution of thienyl for phenyl can significantly enhance the inhibitory activity,especially for compounds 9p(IC₅₀=30.68 n M)and 9r(IC₅₀=30.60 n M),The inhibitory effect on HDAC6 is 104.3 and 128.8 times higher than that of HDAC1,and its activity and selectivity are significantly better than the broad-spectrum HDAC inhibitor SAHA.Fourth,in this project,gastric cancer MGC-803 cells with high expression of HDAC6 was selected as the test cell,and compound 9r,which has excellent HDAC6inhibitory activity and selectivity,was selected to study the biological mechanism.Experiments show that compound 9r exhibits a certain proliferation inhibitory effect on MGC-803 cells(IC₅₀=5.76μM),and can induce MGC-803 cell apoptosis and inhibit cell migration in a dose-dependent manner;BLI and CETSA experiments also confirmed 9r specifically binds to HDAC6.At the same time,in MGC-803 cells,9r can up-regulate the level of acetylatedα-tubulin in a dose-dependent manner,but has no effect on the acetylation of histone H3.In addition,preliminary safety evaluation experiments show that compound 9r has low toxicity,which is of further research significance.To sum up,through literature review,we designed and synthesized 90 novel 1,3-diaryl-1,2,4-triazole derivatives based on the lead compound 1 with potential HDAC6inhibition effect that was screened from our in-house compound library,and evaluated their HDAC6 inhibitory activity,as well as preliminary anti-gastric cancer mechanism.Among them,9r showed the best HDAC6 inhibitory activity(IC₅₀=30.6 n M),and was able to effectively inhibit the proliferation and migration of gastric cancer MGC-803 cells.The successful construction of novel 1,3-diaryl-1,2,4-triazole HDAC6inhibitors not only enriches the structural types of HDAC6 inhibitors,but also provides data support for the development of anti-gastric cancer drugs targeting HDAC6.