Design, Synthesis And Anticancer Activity Of Novel3-aryl Isoindolinone Derivatives

This dissertation is divided into three chapters. In previous work, compoundCDS-1548was found to have anticancer activity through screening. Based on this hitcompound, a series of3-aryl isoindolinones and their analogues were designed andsynthesized for systematic structure optimization. After that, the preliminaryanticancer mechanism of active compounds was studied, and the absoluteconfiguration of the most active isomer was determined.In the first chapter, the background and previous work were described, and thenthe content and meaning of this dissertation was drawn.Today, cancer is a major cause of human death. There are still some drawbacksof existing anticancer drugs, including the poor activity against solid tumors, severeside effects, and the apparent individual differences of efficacy and toxicity, due to thegene diversity of patients and drug resistance. In this way, the development of novelanticancer drugs with diverse structures, efficiency and low toxicity is imperative.Characteristics of cancer cells include unlimited proliferation and resistance toapoptosis. Thus, targeting the regulatory factors of cell cycle and apoptosis pathwayto induce cancer cell cycle arrest and apoptosis, is considered as the efficient strategyfor cancer treatment.All medicines have three basic elements: effective, safe, and quality controlled.There are more stringent requirements for chiral drugs, owing to the differences ofactivity, metabolism or toxicity for different chiral isomers. Therefore, during theresearch and development process, to clarify the activity of each isomer, and develop single enantiomer is necessary.Isoindolinone as a pharmacophore, widely appear in active compounds. Thesubstituents on3-position of the isoindolinone ring system have shown improvedmetabolic stability, and the chiral center is possible to increase the biological activityor reduce the toxicity of active compound. In the previous work, an anticancer activitycompound CDS-1548(IC₅₀=6.5μM, HeLa,48h), with3-aryl isoindolinone scaffoldwas found though screening from the isoindolinone compounds, which were designedand synthesized on the basis of the reported active compound.In this dissertation, based on previous work, the systematic optimization of hitcompound CDS-1548, preliminary mechanism, and chiral-activity relationship ofactive compound were carried out. This work provides reference for the more in-depthstructure-activity relationships study, and lay the foundation for the discovery of leadcompounds, even anticancer drug with novel3-aryl isoindolinone skeleton.In the second chapter, the design, synthesis and anticancer activity studies of theanalogs of hit compound CDS-1548were described.First of all, the design of the analogs of the hit compound was carried out. Thestructure of CDS-1548was divided into A, B, C, D four parts, and two classes ofcompounds were designed. The first class compounds are all3-aryl isoindolinones,and the structure optimization was carried out from three aspects:1) removing A or Cpart to eliminate the chiral center of the4-methoxy phenylethanol fragment, forsimplifying the molecular structure;2) changing the substituent on the benzene ring ofA and B parts;3) changing the hydroxymethyl fragment in C part for other functionalgroups. The second class of compounds, as the analogs of3-aryl isoindolinone withthe modification on isoindolinone skeleton, was designed on the basis of the screeningresult of the first class of compounds. In order to improve drug-likeness, lower LogPand increase the molecular flexibility, the derivatives of CDS-1548were designedreasonably, by way of reducing aromatic rings, introducing of hydrogen bondacceptor or donor and extending alkyl chain. Through the structure optimization, thebest active compound was expected to be found.Secondly, the synthetic routes of the analogues of hit compound were developed. The synthetic methods of3-aryl isoindolinone reported in literatures weresummarized firstly. Based on this, two synthetic routes were developed to build the3-aryl isoindolinone skeleton via the reduction of N-acyliminium ion. Route one: ketoacid was condensed with different primary amine or its hydrochloride to give3-hydroxy-3-aryl isoindolinone intermediate, which was then reduced by cyanosodium borohydride in glacial acetic acid to afford the product. Although the yield ofthis method is low, the substituent on N-can be changed to achieve the moleculardiversity. Route two: the tricyclic γ-lactam was produced by condensation of keto acidwith aminoalcohol in good yield. Then, the diastereomers were synthesized via borontrifluoride ether induced ring-opening of tricyclic lactam substrates, and hydrideaddition of N-acyliminium ion with triethylsilane. The high yield, ease of operationand purification are the advantages of this method, while few types of N-functionalgroup is the limitation. The two routes complemented each other, and thestructure-activity relationship studies were ensured.Finally, designed compounds were synthesized through the two improvedsynthetic routes, and then screened in Hela cells by MTT assay., From the three seriesof3-aryl isoindolinone compounds in the first class, active compounds2-168a (IC₅₀=9.5μM), CDS-3078(IC₅₀=3.6μM) and2-219a (IC₅₀=15μM) were founded. In thesecond class, on the basis of the structure of compound2-168a, isoindolinoneskeleton in D part was modified and a series of3-aryl isoindolinone analogs weresynthesized. Through the screening, active compounds2-245(IC₅₀=10μM) and2-249(IC₅₀=25.4μM) were founded. According to the above results, it suggested thatthe potential target might have a restriction on the structure of compound:1) For thesubstituent on benzene ring of A, B part, and the hydroxymethyl moiety in C part, ifsteric hindered or electrical property did not match, the activity of compound wouldbe disappeard;2) All the active compounds have special configuration, while theirisomers were all inactive. And the activity was lost when the configuration of theactive compound was changed or disappeared. Therefore, we guess that the potentialtarget has a highly conserved spatial structure. In addition, the best active compoundsCDS-3078(IC₅₀=3.6μM, HeLa,48h) was found. Therefore, the chiral-activity relationship of CDS-3078became the goal of the next phase of our studies.In the third chapter, the study of the initial mechanism of active compoundsCDS-1548and CDS-3078, and chiral-active relationship of CDS-3078weredescribed.First, through the analysis by optical microscopy and flow cytometry, it isindicated that CDS-1548and CDS-3078could both arrest cell cycle at the G2/Mphase, and induce the early apoptotic in HeLa cell at10μM, in aconcentration-dependent manner. Second, the more active compound CDS-3078waschosen for the study of chiral-activity relationship. After the synthesis, determinationof chiral purities and absolute configuration of the four isomers of CDS-3078, threedifferent tumor cell lines HeLa, A549and SW1116were chosen for activity screening.Only the （S, S）-isomer3-8was found to induce the apoptosis of three tumor cells,which indicated that3-8had a broad spectrum of anticancer activity. These resultsfurther showed that the potential target of this kind of3-aryl isoindolinones and theiranalogs might be highly conservative, and the protein-small molecule interactionsmight have strong structural selectivity. Further study of mechanism is still inprogress.