Synthesis And Biological Activity Of 2,4-dimethoxy-5-aminobenzoic Acid Methyl Schiff Base Derivatives And Anticancer Mechanism Studies Of Metal Complexes

In this paper,2,4-dimethoxy-5-aminobenzoate was obtained by modifying the amino structure of Platensimycin,and using this structure as the precursor,14 Schiff base organic compounds were synthesized.Their antibacterial and antitumor activities were studied.In addition,the antitumor activity and anticancer mechanistic of two copper and cobalt complexes were also studied.Part 1:14 Schiff base compounds based on methyl 2,4-dimethoxy-5-aminobenzoate were synthesized.In this thesis,14 compounds were characterized by nuclear magnetic（NMR）,mass spectrometry（MS）,and infrared spectroscopy（IR）.At the same time,the antibacterial activity and anticancer activity were tested.14 compounds were screened for antibacterial activity in vitro by micro-fold dilution method.The experiments showed there are significant antibacterial activity of L6,L12,L13,and L14.Among them,L12 shows most significantly antibacterial activityt.The MIC value of L12 is 15.63μg/ml and the MBC value is 31.25μg/ml to ATCC25923.The MIC value of of L12 is 15.63μg/ml and the MBC value is 31.25μg/ml to ATCC25922.The anti-cancer activity of 14 compounds screened by MTT assays in vitro.The experiments showed there are significant anticancer activity of L2,L3,L5,L7,L8,L10,L12,and L14.Among them,L8 shows most significantly anticancer activity,and its IC₅₀ value is 9.04uM to LOVO cells.Part II:The anticancer activity and anticancer mechanism of two Schiff alkali metal complexes（M1 and M3）were studied.The cytotoxicity of complex M1 was evaluated against HeLa,LoVo,A549,A549/cis cancer cell lines,and the normal cell lines LO2 and HUVEC,by MTT assays.IC50 is in the range of 5.13-11.68μM,the anticancer activity is higher than cisplatin and the toxicity to normal cells is lower than cisplatin.In addition,anticancer mechanistic studies shows that M1 inhibits cell proliferation by preventing DNA synthesis,and then acts on nuclear division of HeLa cells over time.Moreover,M1increases intracellular ROS levels in a dose-dependent manner.Western blot analysis showed that M1 greatly reduced the expression levels of c-Myc and KLF5 protein in HeLa.M1 does not inhibit proteasome activity.Finally,M1 induces DNA damage and activates DNA damage repair pathways.The cytotoxicity of complex M3 was evaluated against HeLa,LoVo,A549,A549/cis cancer cell lines,and the normal cell lines LO2 and HUVEC,by MTT assays..In A549/cis,compared with cisplatin（44.79±2.75μM）,the IC50 of the complex M3 is 18.03±2.66μM,and its effect is increased by about 2.48 times.anticancer mechanistic studies shows that complex M3 inhibits cell proliferation by preventing DNA synthesis,and then acts on nuclear division of HeLa cells over time.Moreover,M3 increases intracellular ROS levels in a dose-dependent manner.Western blot analysis showed that M3 reduced the expression levels of target proteins c-Myc and KLF5,and activated many signaling pathways,including ER stress,apoptosis,cell cycle and DNA damage repair in HeLa.M3 does not affect proteasome activity.