Design,Synthesis And Antitumor Activity Of Novel Histone Deacetylase Inhibitors

Objective:Based on the structures of approved histone deacetylase inhibitors（HDACis）and HDACis with isoform selectivities,novel HDACis were designed to target the histone deacetylase 6（HDAC 6）.We expected to obtain selective HDAC 6 inhibitors with anti-tumor activities.Two series of HDACis were designed and synthesized showed in part one and part two,respectively.Methods:A feasible synthetic route was designed by checking relevant literatures.A series of chemical methods such as Click reaction,amide condensation,and nucleophilic substitution were utilized to synthesize the target compounds and the substituents which might have effective selectivity were selected with the help of computer aided drug design（CADD）.The progress of the reaction and the purity of all compounds were monitored by thin layer chromatography（TLC）,and the structures of the compounds were confirmed by ¹H NMR,¹³C NMR,and MS.For the first part of the novel HDACis based on the benzyl-triazole skeleton,the inhibitory abilities of target compounds against HDACs were detected.The compounds whose inhibition rates were more than 90%were selected to test the selectivity toward HDAC 6 by HTRF method,and the IC₅₀0 values of selected compounds against four human tumor cell lines SGC-7901,LoVo,MCF-7,and HL-60 were determined by MTT assay to preliminarily assess their antiproliferative abilities in vitro.The compound with good antiproliferative activity was selected to evaluate its anti-migration ability in vitro,and the binding mode of compounds with HDAC 6 selectivity were analyzed by computer simulation.For the second part of dual targeting inhibitors of HDAC and microtubule polymerization,the IC₅₀0 values against ES-2 and SKOV-3 tumor cells were measured to judge its antiproliferative ability in vitro.Results:The results of TLC in the first part showed that all compounds of ZM series showed single point under UV lamp and purplish red spots by treatment with ferric chloride aqueous solution,indicating that all synthesized final products were pure hydroxamic acid derivatives.The results of ¹H NMR,¹³C NMR,and MS showed that the structures of all synthesized compounds were correct.The enzyme inhibitory activity showed that most of the target compounds possessed good inhibitory effects on HDACs at the concentration of 1μM.Through comparison and analysis of their structures,the inhibition rates of sulfonamide containing compounds were more than90%.The inhibition rate of ZM-26 toward HDACs was 97.1%higher than that of the reference drug,SAHA（96.1%）,indicating that the linkers of these compounds could insert into the active pocket of HDACis and the structure of sulfonamide was more suitable for the interaction between enzymes and ligand.The results of selectivity test showed that the HDAC 6 selectivity of compound ZM-23 was better than that of ACY-1215,while compound ZM-26 could potently inhibit the activity of HDAC 6,with the IC₅₀0 value of 8.4nM.The results of MTT assay showed that compounds ZM-22 to ZM-27 could inhibit the proliferation of HL-60 tumor cells at low concentration（μM）.Compound ZM-26 exhibited the strongest antiproliferation ability in vitro and remarkable anti-migration activity of MCF-7 tumor cells,which was consistent with its enzyme inhibitory activity.Finally,the molecular docking of compound ZM-23 and ZM-26 to HDAC 6 was carried out.The second part depict a series of HDAC and tubulin polymerization dual targeting inhibitors,compound Z-9-7S displayed extremely potent anti-proliferative activity against two ovarian cancer cell lines.Other activity evaluation work of this compound is still on the way.Conclusion:The two series of compounds were designed and synthesized to inhibit HDACs,and the second series is worthy of further activity evaluation and structural optimization works.