Synthesis And Biological Evaluation Of Tetrahydroquinoxaline And Quinoxaline Derivates As Tubulin Polymerization Inhibitors

Microtubules,which are composed of a-and P-tubulin heterodimers,play an important role in various cellular processes,including spindle formation,cellular shape maintenance,and intracellular transport of substances.In the eukaryotic cell cycle,tubulin aggregates into the mitotic spindles which aid the segregation of sister chromatids to produce two daughter cells.Therefore,the function of microtubules in cell mitosis makes them an attractive target in the development of anticancer drugs.The microtubule-targeting agents disrupt microtubule dynamic and arrest cancer cells in G2/M phase,and this would eventually induce cell apoptosis.In this context,microtubule-targeting agents have been widely investigated in the treatment of cancer.Compristin A-4(CA-4),a naturally occurring cis-stilbene derivative isolated from the bark of the South African shrub,is proved to be an effective inhibitor binding to the tubulin colchicine site.It exhibited potent cytotoxicity against a broad spectrum of human cancer cell lines.However,it is greatly limited in clinical use due to the low water solubility of CA-4 and the isomerization to its inactive trans-structure during storage and administration.Phenstatin which is analogue of the CA-4 with the double bond being replaced by a carbonyl group showed potent cytotoxicity and antitubulin activity similar to CA-4,but it is more stable compared with CA-4.Quinoxaline,a heterocyclic compound containing a benzene ring and a pyrazine ring,has been widely used in pharmaceutical chemistry in virtue of its good physicochemical properties and biological activities.Based on the above research background as well as previous work of our group,we performed the design and synthesize of two series of target compounds that are not reported in the literature in this thesis.The main contents of the thesis are as follows:1.In this dissertation,32 novel target compounds with tetrahydroquinoxaline and quinoxaline skeleton structure were synthesized.Their structures were well confirmed by 1H NMR,13C NMR and ESI-MS.2.The in vitro antitumor activity of all target compounds was tested against human cervical carcinoma cell line(HeLa),human hepatoma cell line(SMMC-7721)and human colon cancer cell line(HT-29).3.The mechanism of action of the target compound 12b was studied through in vitro tubulin polymerization inhibition,cell cycle arrest,and immunofluorescence assay.The results of MTT test demonstrated that the half inhibitory concentrations of compounds 12b,13c,19b,19c,and 19d against three tumor cell lines reached nanomolar levels and were superior to the positive control doxorubicin.Based on the test results,a preliminary structure-activity relationship of all compounds was concluded.From the results of mechanism investigation,we found that compound 12b was to be able to inhibit tubulin polymerization,interfere with microtubule formation,and induce significant cycle arrest.Finally,the molecular docking was used to explore the mode of action of compound 12b on the colchicine binding site.