Interactions With G-quadruplex DNA And Anticancer Activity Of Ruthenium Complexes

Ruthenium?II?complexes that have excellent photophysical and photochemical properties,variable oxidation states,outstanding biological activity and strong binding affinity to DNA have been the focus in bioinorganic chemistry in recent years.This dissertation is concertained about the interactions with G-quadruplex DNA and antitumor activity of ruthenium complexes,which includes the followings:1.The interactions of complexes 1-5 with c-myc Pu22 DNA were studied by UV absorption spectra,fluorescence spectra,Job plot,circular dichroism?CD?spectra,PCR?polymerase chain reaction?amplification,color reaction,fluorescence resonance energy transfer experiment?FRET?.The inhibitory activities of complexes 2 and 3 against topoisomerase were investigated by agarose gel electrophoresis.The results suggested that:?1?Complexes 1,2,3 and 4 can induce Pu22 DNA to form a G-quadruplex structure,and 1,2and 4 bond to Pu22 quadruplex through groove mode.For complexes 1,2,3 and 4,the binding constants to Pu22 DNA were 2.33×10⁶ M^-1,1.47×10⁶,4.45×10⁷ M^-1 and 1.75×10⁶ M^-1,and the binding stoichiometry were 2:1,1:1,2:1 and 2:1,respectively.Complexes 1,3,and4 showed good stability and selectivity for Pu22 quadruplex with the?T_m values of 13?,12?and 7?,respectively.However,the stability and selectivity of complex 2 for Pu22quadruplex were weak,giving the?T_m value only 3?.?2?Although complex 5 cannot induce the formation of Pu22 quadruplex,it exhibited promising stability and selectivity for Pu22 quadruplex,which increased the T_m value by 15?.Especially,the complex showed remarkable luminescence enhancements of 20.9-times for quadruplex binding,acting as an excellent quadruplex-induced“off-on”luminescence switch.?3?Complexes 2 and 3 can block the DNA strand passage event of the topoisomerase enzyme at 4?M and 6?M,respectively,serving as an inhibitor of topoisomerase I.2.The inhibitory activities of complexes 1,2,4 and 6 on six kinds of cancer cell lines A549?lung cancer?,Huh-7?hepatocarcinoma?,MGC-803?gastric cancer?,MCF-7?breast cancer?,HepG-2?hepatocarcinoma?,HeLa?cervical carcinoma?and a normal cell line 293T?embryonic kidney cell?were studied by MTT assay,DAPI staining,and apoptosis assay.The results suggested that:?1?Complexes 1,2 and 4 showed moderately cytotoxic activity toward MCF-7 cells with IC₅₀ values of 31.65?M,15.01?M and 52.40?M.Complex 6 exhibited moderately cytotoxic activity toward HeLa cells with IC₅₀ values of 49.17?M.Significantly,complex 4 was less cytotoxic against 293T cells with IC₅₀ value of 121.04?M,indicating that it has selectivity for cancer cells over normal cells.?2?Complexes 2 and 4 can cause MCF-7cells death mainly through the apoptotic pathway.With an increase in the concentrations of complex 4,a greater population of MCF-7 cells was in apoptosis,and the percentage of apoptotic cells increased from 19.62%to 33.72%.