Studies On Synthesis,Structural Characterization And Antitumor Activities Of Copper,Palladium And Rhodium Complexes With Isoquinoline Derivatives As Ligand

Transition metal complexes have been used for the treatment of many diseases such as cancer,bacterial infection,and inflammation during the past few decades.In the field of cancer chemotherapy,platinum complexes have attained notable achievements for their clinical applications.The platinum complexes approved and used widely for the treatment of cancer include cisplatin,carboplatin,and oxaliplatin.Cisplatin is used for the treatment of ovarian,testicular,bladder,non-small lung,head,and neck cancers.However,acquired resistance and toxicity cause severe side effects and limit the clinical application of these drugs.For example,the common side effects of platinum complexes are nephrotoxicity,ototoxicity,nausea and vomiting,diarrhea,and loss of sensation and paresthesia.These side effects are owing to the low selectivity for cancer cells.The metal complexes showing single anticancer mechanisms are typically not effective in the treatment of tumors and they produce drug resistance and toxicity,because cancer is a multigenetic and complicated disease.Therefore,to overcome these side effects and multi-drug resistances,the development of multi-targeted anticancer agents is most desirable.At present,drugs with multitargeting capability are highly sought to overcome the drawbacks of single targeting drugs.Transition metal complexes can be designed as multi-targeted anticancer agents.Currently,the design and synthesis of transition metal complexes with organic ligands possessing anticancer activity has been the focus of cancer chemotherapy.This is considered a promising strategy to develop potential anticancer agents because the metal complexes usually possess higher biological activities than the corresponding free organic ligands,and exert a synergistic effect after the formation of coordination compounds.Isoquinoline alkaloids are commonly found in nature,and they exhibit different kinds of biological and pharmacological activities,such as the inhibition of cellular proliferation and cancer cell growth.Berberrubine,a compound of protoberberine alkaloids,is active against tumors in animal models.Another isoquinoline alkaloid,[1,3]-dioxolo-[4,5-g]-isoquinoline?papraline?,which was isolated from the aerial part of Fumaria indica,is considered as a mild analgesic,laxative,and diuretic agent and beneficial for skin scrofulous infection and dyspepsia.Based on the merits of isoquinoline alkaloid three,isoquinoline alkaloid derivative ligands and their six metal complexes including copper,palladium and rhodium have been designed,synthesized and characterized.Bimodal death through apoptosis and autophagy in A549 and Hep G2 cells were also investigated.These complexes interacted through various pathways such as apoptosis via the mitochondrial-mediated pathway,apoptosis via the MAPK-mediated pathway,LC3-?-mediated autophagy,and cell damage through the endoplasmic reticulum stress-mediated pathway.In addition,the in vivo anticancer activities of these complexes were conducted on tumor xenograft models of mice bearing A549 and Hep G2 cells,respectively.This thesis is composed of the contents that follow.Chapter 1:In this chapter,the different types of cancers and their treatments,including surgery,radiation therapy,and immunotherapy with emphasis on chemotherapy,are reviewed and discussed.In addition,the use of metals in medicine,particularly for the synthesis of anticancer metal complexes and the interaction of drugs with DNA via intercalation and groove binding modes,are discussed as well as cancer chemotherapeutic agents.Moreover,platinum-based anticancer agents,such as cisplatin,carboplatin and oxaliplatin,their action mechanisms with multidrug resistance,as well as the importance of structure activity relationships for the development of non-platinum complexes are discussed.Then in the last part of this chapter,the anticancer complexes of copper,palladium and rhodium are summarized and reviewed.Chapter 2:In this chapter,the synthesis of three ligands,“L¹”2-?6,7-dimethoxyisoquinolin-1-yl?aniline,“L²”2-?6-methoxyisoquinolin-1-yl?aniline and“L³”6-methoxy-1-?-2-aminophenyl-?-3,4-dihydroisoquinoline,and six metal complexes:[Cu L¹Cl₂]?1?,[Cu L²Cl₂]?2?,[Pd?L¹?Cl₂]?3?,[Rh?L¹?Cl₃?DMSO?]?4?,[Rh?L²?Cl₃?DMSO?]?5?,[Pd?L³?Cl₂]?6?are described and characterized by ¹H-NMR,¹³C-NMR,ESI-MS,IR and elemental analysis,and single crystal X-ray diffraction analysis.The crystal structures of complexes 1 and 2 are briefly described as isoquinoline is a bidentate ligand with two nitrogen donors?L¹-N^N and L²-N^N?bound to copper forming a distorted square planar geometry.Complexes 3 and 6 also have distorted square planar geometry.In both of the two complexes,two atoms of chlorine and the heterocyclic nitrogen from bidentate aminophenyle isoquinoline ligands are coordinated to a central Pd?II?.The complexes 4 and 5 adopt six-coordinated distorted octahedral geometry,in which one bidentate aminophenyle isoquinoline,three chlorine atoms,and one dimethyl sulfoxide are bonded to a Rh?III?center.The stability of all these complexes were measured by UV-Vis spectroscopy and HPLC?high performance liquid chromatography?,and they were found stable at p H 7.4 in DMSO and PBS solution for 24 hours at room temperature.Chapter 3:In this chapter,the in vitro and in vivo anticancer activities and the possible anticancer mechanisms of the copper and palladium complexes,against A549 and Hep G2 cell lines,are explored and discussed.The copper complexes exhibited high cytotoxic activity towards different cancer cell lines including A549 lung cancer cell lines,and low cytotoxicity towards human normal cells.Mechanistic study showed that the copper complexes induced cytotoxicity via apoptotic and autophagic signaling pathways.Complexes 1 and 2 targeted mitochondria,resulting in the depolarization of mitochondrial membrane potential,and increases of ROS level and ER-stress.Furthermore,complexes 1 and 2 regulated the pro-death autophagy proteins such as Beclin1,p62,LC3-1 and LC3-? and induced autophagy.Experimental results also indicated that complexes 1 and 2 effectively inhibited the tumor growth in a xenografted mouse model bearing A549 cells,and exhibited lower in vivo toxicity than cisplatin.The palladium and rhodium complexes 3-6 exhibited higher in vitro anticancer activity and lower toxicity than their corresponding ligands and cisplatin against Hep G2 cell lines.The mechanistic studies revealed that among these complexes,complex 3 arrested the cell cycle at S-phase by the regulation of cyclin and cyclin-dependent kinases.The accumulation of complex 3 in mitochondria induced ER-stress and elevated ROS,and stimulated Ca²⁺release that activated the caspase cascade and ultimately caused mitochondrial-mediated apoptosis and autophagic cell death.The in vivo studies of complex 3 demonstrated that it possesses higher safety than cisplatin and could effectively inhibit tumor growth in mice model.The difference in the biological behavior of the complexes may be related to the number and position of methoxy groups on the ligands.All of these results suggest that complexes 1 and 3 could be developed as potential anticancer drug candidate,or they could serve as a foundation for further development of anticancer drugs.