Structure Optimization And Activity Study Of Procapase-3 Activator

In recent years,designing apoptosis-inducing antitumor small molecules for key proteins in the apoptotic pathway to restart tumor cell apoptosis has become one of the important strategies for tumor treatment.Caspase-3,a key executive protein in the downstream of the apoptotic pathway,plays an important role in cell apoptosis.The development of small-molecule drugs that directly activate procaspase-3 to caspase-3has become a new way to overcome mid/upstream apoptotic protein mutations and restart tumor cell apoptosis.This article introduced the apoptotic pathway and the relationship between cancer and apoptosis,and highlighted the research progress of procaspase-3 protein and its activators,as well as the design,synthesis and antitumor activity evaluation of pyridine/benzene-semicarbazone derivatives containing a benzothiazole/benzene moiety.Based on the structures of the preferred compounds in previous studies.The o-hydroxy-acylhydrazone moiety was replaced by pyridine-acylhydrazone,and the hydrazone terminal lipophilic groups was removed to reduce liposolubility and improve drugability,a series of pyridine-acylhydrazone derivatives containing a benzothiazole moiety were designed?series 1?.In additon,a phenyl group was substituted for the benzothiazole group in order to investigate the importance of the benzothiazole group,thus a series of pyridine-acylhydrazones containing a phenyl group were designed?series 2?.In order to further investigate the importance of the N,N,O donor moiety,the 2-pyridyl group was replaced with a phenyl group to obtain a series of phenyl-acylhydrazone derivatives containing benzothiazole/benzene moiety?series 3?.Based on the structures of the three series of target compounds,a reverse synthesis analysis method was used to design and determine the synthetic routes of the target compounds.The synthesis methods and reaction conditions were determined according to the synthetic routes.As a result,a total of 25 target compounds were synthesized,their structures were confirmed by HRMS,¹H-NMR and ¹³C-NMR.Taking PAC-1 as the reference drug,all target compounds were evaluated for their in vitro antitumor activity against two cancer cell lines including one procaspase-3 over-expression cancer cell line?U937?and one procaspase-3low-expression cancer cell line?MCF-7?by using CCK-8 assay.The results showed that the pyridine-acylhydrazone derivatives containing a benzothiazole moiety?series1?showed significant antitumor activity and selectivity,among them,compounds 8j and 8k showed promising activity against U937 cells with the IC₅₀0 values of 5.2?M and 6.6?M,respectively.Moreover,in order to study further their mechanism of action,8j and 8k were selected to test the apoptosis,caspase-3 activation activity and procaspase-3 activation activity.The results showed that 8j and 8k could inhibit proliferation of cancer cells by inducing apoptosis via activating procaspase-3 to caspase-3,their activation rates were 77.8%and 92.1%,respectively.Based on the results of the antitumor activity,the structure-activity relationships of target compounds were analyzed and discussed,which provided an important guidance for further research.