Research On Cell Cycle G₂/M Checkpoint Inhibitors Synthesis And Activity

Looking for high available tumor therapy has been the hotspot of research.Themain characteristics of tumor cells represents unlimited proliferation, which is relatedto the defects in cell cycle checkpoint. The checkpoint is of great significance toensure the genetic stability and integrity. According to research, most human tumorcells present p53mutation leading to G1/S checkpoint deletion, then the tumor cellsrely on the remaining S and G₂/M checkpoints more, especially the latter, when DNAsuffered from injury. So it’s considered to discover specific G₂/M checkpointinhibitors abolishing blockage of tumor cells in the G₂phase, which force them to getinto mitotic phase directly without repair, increase their apoptosis and kill themselectively, whereas normal cells are not affected due to the block in G1phase. Thecombination of specific G₂/M checkpoint inhibitors and traditional anticancer drugsdevelops a new direction for more effective cancer treatment.Aryl （heteroaryl） carbazoles as G₂/M checkpoint inhibitors have been reportedmost until recently. UCN-01is a nonselective Chk1inhibitor and has been proved toproduce a good selective sensitizing effect for chemotherapy or radiotherapy byabolishing of S or G₂/M checkpoint. But clinical research found that UCN-01hadsevere plasma adverse reactions decreasing bioavailability.On the basis of theirstructure activity relationships, we expect to get ideal G₂/M checkpoint inhibitors forcancer treatment by structural modification of UCN-01. Structural modifications are as follows:①Remove glycosyl E to improveadverse effects binding plasma glycolproteins and bioavailability;②Introduce sidechains （-CH2CH2CH2NR1R2,-CH2CH2CH2X） containing different amino or halogento one indole NH and expect to get active UCN-01analogues refering to the positionof methylamine group in UCN-01skeleton and biological isostere principle;③Reduce the synthesis difficulty by substituting carbonyl for7-hydroxyl and increasestructural symmetry;④R eplaceone of indoles from other aryl （benzene,etc.） andinvestigate effect of conjugated aromatic rings’ numbers and sorts on activity;⑤OpenB cycle to get bisindolylmalimides possessing potential PKC inhibitory activity.Target compounds were derived from methylsulfonylation, bromination,photoreaction, ammonolysis of the intermediates, which were prepared by couplingreaction of substituted methyl-indole-glyoxylate with （substituted） aryl acetamidesusing t-BuOK in THF as catalyst and treatment using concentrated hydrochloric acidsubsequently. Five bisindolylmalimides and fourteen indolyl（benzene）carbazoles aresynthesized through efforts, seventeens as novel compounds,which provides materialbasis for screening anticancer drugs of G₂/M checkpoint inhibitors and a feasiblesynthetic route for preparing more analogues.In addition to synthesize17novel compounds, the study is the first to discoverthat bisindolylmaleimides having substituents on two indoles NH could be convertedto corresponding indole carbazoles high yield by photoreaction using I2as catalyst ifone of substituents is bromo alkyl. According to the previous reports, the yield isextremely low for photoreaction of bisindolylmaleimides having substituents on twoindoles NH （not containing-Br） while the reaction could be completed effectively byusing expensive reagents such as Pd（OAc）2.Evaluation of drug activity is carried out by using MTT analysis to investigatecytotoxicity and flow cytometry to determine tumor cells cycle distribution aftertreatment using different concentrations drugs respectively, then effect can beelucidated by comparision. The results are helpful to do research further.