Preparation Of Novel Antitumor New Ruthenium (Ⅱ) Complexes And Study On Their Mode Of Actions

Although platinum-based antitumor drugs play important roles in clinical treatment,their insurmountable side effects and drug resistance limit their application to a large extent.Therefore,more and more researchers have been exploring and studying other metal-based complexes to overcome these limitations.In recent years,ruthenium complexes have been widely developed and studied due to their stable oxidation states,excellent biological properties,and structural diversity.To date,four ruthenium antitumor complexes have entered clinical trials.Bsed on the discussion above,herein,three series of complexes have been designed and synthesized based on two types of structures of ruthenium（Ⅱ）complexes（arene ruthenium（Ⅱ）complexes and polypyridyl ruthenium（Ⅱ）complexes）.Furthermore,their in vitro cytotoxicity was evaluated by MTT colorimetric method as well as modes of action was explored at the biomolecular level.The main contents of this paper are summarized as follows:（1）For the first series,four dinuclear organoruthenium（Ⅱ）complexes Ⅰ-1～Ⅰ-4 containing different schiff base ligands were designed and synthesized.The structures of the complexes were confirmed by ¹H and ¹³C NMR spectra along with ESⅠ-MS spectrometry.In vitro cytotoxicity experiments showed that the obtained complexes exhibited moderate antiproliferative activity against the tested cancer cells.It was worth noting that Ⅰ-4 showed comparable cytotoxicity to cisplatin.Spectrometric titration,molecular docking and agarose gel electrophoresis experiments showed that complexes Ⅰ-1 and Ⅰ-2 could covalently bind with DNA,while complexes Ⅰ-3 and Ⅰ-4 interacted with DNA through intercalation interaction.Meanwhile,complexes Ⅰ-1～Ⅰ-4 could produce a large amount of ROS in tumor cells and further induce ER stress.These results suggested that these dinuclear ruthenium（Ⅱ）complexes exerted their antitumor activity through DNA binding and ROS-mediated ER stress pathways.（2）For the second series,two curcumin-based polypyridyl ruthenium（Ⅱ）complexes Ⅱ-1and Ⅱ-2 were designed and synthesized,both of which showed considerable anti-tumor activity.The spectrometric titration and molecular docking experiments showed that complex Ⅱ-1 may interact with DNA through groove binding,while complex Ⅱ-2 may interact with DNA through intercalation.Further weatern blot indicated that the obtained complexes can prevent the phosphorylation of MEK1 and ERK1 in A549 cells.Therefore,the resulting complexes can induce apoptosis through DNA damage and the MEK/ERK signaling pathway.（3）For the third series,five polypyridyl ruthenium（Ⅱ）complexes Ⅲ-1～Ⅲ-5 containing schiff base ligands were designed and synthesized.Then the structures of the complexes were confirmed through a series of characterization methods.DFT calculations showed that the HOMO-LUMO energy gaps of the complexes Ⅲ-1～Ⅲ-5 were smaller than that of[Ru（bpy）₃]Cl₂,so the ¹MLCT absorption bands of Ⅲ-1～Ⅲ-5 were redshifted as compared with[Ru（bpy）₃]Cl₂.The cytotoxicity results showed that complex Ⅲ-5 showed extremely high cytotoxicity upon 650 nm irradiation with the IC₅₀ values of 56 n M and 63 n M against A549 and Hep G2 cell lines,respectively.Agarose gel electrophoresis and molecular docking experiments showed that complex Ⅲ-5 exhibited considerable DNA photocleavage activity due to its strong DNA binding ability and high ¹O₂ production efficiency.