DNA Binding And Antitumor Activity Of Methyl Benzoatecorrole Copper And Gallium Complexes

Many anticancer drugs and chemotherapeutic agents are designed to target DNA. These drugs may give rise to DNA damage in tumor cells, constrain tumor cell proliferation, and ultimately result in cell death or apoptosis. Corroles and their complexes have potential application in cancer therapy. It was identified that many metallocorrolates exhibit cytotoxicaction against tumor cell lines. The research on interaction between corroles and DNA may provide useful information for their application in medicine. Previous studies have identified that corroles and their complexes can bind to DNA, show excellent nuclease activity and also are a new class of G-quadruplex stabilizers. To continue our study in the biomedical application of corroles, this thesis focus on the interaction between DNA and methyl benzoate gallium corroles or copper corroles. Furthermore, cytoxicity on tumor cells of corroles of gallium corroles was also investigated. The main contents of this thesis are as follows:Firstly, 10-(4-Methoxycarbonylphenyl)-5,15-bis(pentafluorophenyl)corrole(1) and 5,15-bis(4-Methoxycarbonylphenyl)-10-(pentafluorophenyl)corrole(2) and their copper and gallium complexes(1-Cu, 2-Cu, 1-Ga, 2-Ga) were synthesized and characterized by UV-Vis, MS, NMR spectra.Secondly, the binding mode of these corrole complexes with CT-DNA was studied by fluorescence methods, UV–visible, viscosity measurements. The results indicated all corrole complexes interact with DNA via groove binding. Molecular docking revealed 1-Ga and 2-Ga are located in the major groove of double-helix DNA.Thirdly, the nuclease activities of these corroles and their complexes were studied by agarose gel electrophoresis experiments. The results showed free base corrole 1, 2 and their gallium complexes 1-Ga, 2-Ga show excellent photonuclease. Photonuclease activity of 1 and 2 enhanced drastically when bound to a metal gallium ion. The DNA cleavage by 1-Ga or 2-Ga was observably inhibited by adding the singlet oxygen(1O2) scavenger. The rate of 1O2 production was determined by DPA as a chemical probe. These results suggested that the generation of single oxygen is indeed occurred in the presence 1-Ga or 2-Ga upon irradiation. Compare with 2-Ga, 1-Ga have higher DNA singlet oxygen production rate under irradiation. 1-Cu and 2-Cu lose the ability of generation of single oxygen under irradiation and do not show photonuclease. However, 1-Cu and 2-Cu could cleave DNA efficiently, in the presence of hydrogen peroxide/sodium ascorbate through superoxide pathway.Fourthly, the cytotoxicity of 1-Ga and 2-Ga against human hepatocarcinoma cells(QGY-7701) and human hepatocellular cells(MHCC-H/L) were evaluated by MTT assay. The result indicated that 1-Ga and 2-Ga have little dark toxicity to QGY-7701 cell and MHCC-H/L cell lines(IC50>40 μM). However, 1-Ga and 2-Ga show high photocytotoxic activity against the selected cancer cell lines. The IC50 values of 1-Ga against QGY-7701 cell and MHCC-H/L cell reach 3.92, 16.02 μM respectively. The IC50 values of 2-Ga against QGY-7701 cell and MHCC-H/L cell reach 3.58, 9.62 μM under irradiation respectively. The results imply that 1-Ga and 2-Ga may have potential application in photodynamic therapy as photosensitizers.Fifthly, fluorescence probe tests showed the absorbed 1-Ga and 2-Ga in tumor cells were mainly localized in mitochondria on QGY-7701 cell. After irradiation, they will cause the mitochondria membrane potential disruption, which leads to the final destruction of tumor cells.