Design,Synthesis And Biological Evaluation Of Benzo[cd]indol-2(1H)-ones Derivatives As BRD4 Inhibitors

Bromodomain is a class of conserved protein domains that specifically recognize acetylated lysine（KAc）in histones.It can be divided into eight different bromodomain groups,BET is one of them.BRD4,the most extensively studied member of the BET family,is an epigenetic regulator that localizes to DNA via binding to acetylated histones and controls the expression of therapeutically important gene regulatory networks through the recruitment of transcription factors to form mediator complexes,phosphorylating RNA polymerase II,regulating the transcriptional expression of genes.Typical small molecule inhibitors of BRDs are usually designed to mimic acetylated lysine residues and disrupt the protein-protein interactions between BRD4 and acetyl-lysine,Inhibits disease-related gene expression.so forth,the development of BRD4 inhibitors has become a research hotspot.In this paper,on the basis of synthesis of the structure-activity analysis of Bromodomains inhibitors.F-BD-1 bearing with benzo[cd]indol-2（1H）-one scaffold was identified as an effective BRD4 inhibitor through the AlphaScreen-based high-throughput screening.Aryl sulfonyl chloride is obtained by the reaction of 1.8-naphthalene imide with chlorosulfonic acid,followed by the arylsulfonyl chloride reacted with tetrahydropyrrole to obtain an intermediate 2,Then 2 reaction with chloroethyl to obtain compound F-BD-1.We optimized the structure of compound F-BD-1.The optimization is mainly concentrated in two parts:1)The lactam moiety on the guanidine ring.intermediate 2 reacted with various of halogenated compounds to synthesized compounds F-BD-1-F-BD-29;2)pyrrole ring portion which occupying hydrophobic region of WPF,an arylsulphonyl chloride reacted with various secondary amines and amino acids to synthesized compounds F-BD-30-F-BD-77.We synthesized 77 compounds,the structures of compounds were determined by NMR,MS.All the compounds were evaluated for their BRD4_BD1 inhibitory activities,The results show that most of the compounds modified at lactam have no enzyme inhibitory activity,suggesting that the ethyl group attached to the lactam is the most favorable group to accommodate well into the acetyl lysine site of the KAc binding pocket.However most of the compounds modified at the pyrrole ring have good inhibitory activity.The results showed that compounds F-BD-38,F-BD-39,F-BD-59 and F-BD-45 are the most potential ones with the IC₅₀ values of 1.02μM,1.43μM,1.55μM and 3.02μM.In the same time,we determined the co-crystal structures of above mentioned compounds in complex with BRD4-BD1.The analysis of structure-activity relationship indicated that pyrrole and piperidine ring with hydroxy group or amino group contributes to binding of the compound to the protein and increase of compound activity.