Design,Synthesis And Bioactive Evaluation Of Novel Tubulin Inhibitors As Anticancer Drugs

Cancer has become one of the major causes of death worldwide,and there is an increasing trend year by year.Currently,a variety of antitumor drugs have been applied in clinical therapy.While,some knotty problems also exist,such as hard to distinguish normal cells from tumor cells,prone to drug resistances and serious side effects.Therefore,antitumor drugs with low toxicity,few side effects and unique target are in urgent need for cancer therapy.Tubulin inhibitors are new pharmaceuticals that have been used for cancer control and received much concern due to target specificity,potent antitumor activity and damage on tumor angiogenesis.Given proper physiochemical feature and simple structure of colchicine binding site,one of the four classical microtubule binding sites,an increasing number of researches are focused on colchicine-like compounds.According to the reported tubulin inhibitors recent years and accumulation of our research group,we constructed a tubulin inhibitor molecule database containing excellent active fragments,such as:indole,benzimidazole,thiazole,pyrazol,amide,sulfamide,ketoxime,with the help of computer modeling technique.Compounds with excellent virtual activity were screened out.Based on the principle of combinatorial chemistry,we designed and synthesized 5 series,109 novel tubulin inhibitors.We have identified their structures with 1H NMR,13C N-MR and MS,and 9 compounds'three dimensional space structures were identified by single crystal parsing technologies.In addition,the bioactivity and structure-activity relationship of these compounds were evaluated systematically.The main results were briefly as follows.(1)Indole grafted Benzimidazole-containing benzamide derivatives24 novel indole grafted benzimidazole-containing benzamide derivatives(A1-A24)have been synthesized.For antitumor activity,6(25%)compounds exhibited better than colchicine,3(12.5%)compounds showed better than CA-4.Among these compounds,compound A14 exhibited the best activity against tubulin polymerization(IC50=1.5 ?M),which was better than CA-4(IC50=1.8 ?M)and colchicine(IC50=2.62?M).Besides,compound A14 also revealed the best anti-proliferation activity against A549,HepG2 and MCF-7 cells(ICso=2.4 ?M,3.8 ?M,5.1 ?M,respectively),which was better than CA-4(IC50=2.8 ?M,7.4?M,9.4?M,respectively)and colchicine(IC50=4.4?M,10.5?M,13.5?M).Furthermore,flow cytometry analysis results displayed that compound A14 could induce cell apoptosis and arrest cell cycle at G2/M phase.Cytotoxicity assay exhibited that the series of compounds have no toxicity against human,and they could be further developed as potent anticancer drugs.Structure-activity relationship of these 24 compounds demonstrated that OCH3 in A ring and electron-donating substituted groups in meta-position of B ring could enhance the antitumor activity.(2)Indole grafted benzimidazole-containing benzsulfamide derivatives22 novel indole grafted benzimidazole-containing benzsulfamide derivatives(B1-B22)have been synthesized.For antitumor activity,5(22.7%)compounds showed better than colchicine,3(13.6%)compounds showed better than CA-4.Among these compounds,compound B19 exhibited the best activity against tubulin polymerization(IC50=1.41?M),which was better than CA-4(IC50=1.9?M)and colchicine(IC50=2.54?M).Besides,compound B19 also showed the best anti-proliferation activity against A549 cell(IC50=1.6?M),which was better than CA-4(IC50=2.2 ?M)and colchicine(IC50=4.1?M).Furthermore,cell apoptosis and cell cycle results displayed that compound B19 could arrest cell cycle at G2/M phase and effectively induce cell apoptosis.Immunofluorescence also proved that compound B19 could inhibit tubulin polymerization.Structure-activity relationship of these 22 compounds demonstrated that OCH3 in A ring,CH3 in B ring and multiple electron-donating substituted groups in C ring could enhance the antitumor activity.(3)Chalcone oxime derivatives18 novel chalcone oxime derivatives(C1-C18)have been synthesized.For antitumor activity,2(11.1%)compounds showed better than CA-4.Among these compounds,compound C7 exhibited the best activity against tubulin polymerization activity and anticancer cell activity(Tubulin:IC50=1.6,uM,A549:IC50=2.1 ?M,Hela:IC50=3.5 ?M,MCF-7:IC50=3.6?M),which was better than CA-4(Tubulin:IC50=1.8?M,A549:IC50=3?M,Hela:IC50=9.3?M,MCF-7;IC50=8.4 ?M).Results of cell apoptosis and cell cycle displayed that compound C7 could arrest cell cycle at G2/M phase and induce cell apoptosis.Structure-activity relationship of these 18 compounds demonstrated that 2,4,6-(OCH3)3 in A ring and electron-donating group in B ring could enhance the antitumor activity(4)Indole grafted thiazole hydrazone derivatives22 novel indole grafted thiazole hydrazone derivatives(D1-D22)have been synthesized.Most compounds exhibited good antitumor activities,especially compounds D18,D16,D22 and D10.Among these compounds,compound D18 showed the best activity against tubulin polymerization(IC50=1.28?M),which was better than CA-4(ICso=2.1,uM)and colchicine(IC50=3.2 ?M).Moreover,compound D18 also showed the best anti-proliferation activity against A549 cell(IC50=0.4 ?M),which was better than CA-4(IC50=7.4?M)and colchicine(IC50=10.5 ?M).Results of cell apoptosis and cell cycle displayed that compound D18 could arrest cell cycle at G2/M phase and effectively induce cell apoptosis.Immunofluorescence further proved that compound D18 could inhibit tubulin polymerization.Structure-activity relationship of these 22 compounds demonstrated that H on R1,OCH3 on R2,meta-position substituent on R3 could enhance the antitumor activity(5)Benzimidazole grafted benzsulfamide-containing pyrazole ring derivatives23 novel benzimidazole grafted benzsulfamide-containing pyrazole ring derivatives(E1-E23)have been synthesized.For antitumor activity,3(13%)compounds showed better than colchicine,1(4.3%)compound showed better than CA-4.Among these compounds,compound E18 displayed the most potent antitubulin activity and anti-proliferation activities(Tubulin:IC50=1.52 ?M,A549:IC50=0.15?M,Hela:IC50=0.21?M,HepG2:C50=0.33?M,MCF-7:ICso=0.17?M),which was notably better than CA-4(Tubulin:IC50=1.52 ?M,A549:IC50=0.15 ?M,Hela IC50=0.21 ?M,HepG2:C50=0.33?M,MCF-7:IC50=0.17 ?M)and colchicine(Tubulin:IC50=1.52 ?M,A549:IC50=0.15?M,Hela:IC50=0.21?M,HepG2:C50=0.33?M,MCF-7:IC50=0.17?M).Cell apoptosis and cell cycle results displayed that compound E18 could arrest cell cycle at G2/M phase and effectively induce cell apoptosis.Immunofluorescence also proved that compound E18 could inhibit tubulin polymerization.In vivo anti-tumor activity conducted in mice demonstrated that compound E18 could validly inhibit cancer.Structure-activity relationship of these 23 compounds demonstrated that CF3 in the para-position of A ring and multiple electron-donating substituted groups in B ring could enhance the antitumor activity.