Synthesis,Crystal Structure And Anti-Hepatic Carcinoma Activity Of Two Novel Mg(Ⅱ)-based And Zn(Ⅱ)-based Metal Complexes

Backgroud Hepatic carcinoma is a type of cancer that has a very high mortality rate in the world.The clinically used treatments include surgical resection,liver transplantation,chemotherapy,and radiation therapy.Since liver surgery is only applicable to a small percentage of patients in the early stage of hepatic carcinoma,traditional chemotherapy is still an important treatment strategy for hepatic carcinoma.In chemotherapy,accidentally discovered cisplatin with anticancer activity has achieved great success in clinical treatment,however,the efficacy of cisplatin is largely limited by drug resistance and some toxic and side effects.In order to overcome these deficiencies of cisplatin drugs and to obtain a broader spectrum of anticancer drugs,this has greatly promoted the design,synthesis and application of novel metal anticancer drugs.The important components of metal complexes are a wide variety of ligands.Among them,carboxylic acid complexes containing oxygen atom-based polydentate ligands and nitrogen-containing heterocyclic complexes containing nitrogen atom-based polydentate ligands are highly versatile.The varity pattern and strong coordination ability make it easy to form three-dimensional topological structures with novel and diverse structures and unique properties.Therefore,it is the most commonly used ligand for the synthesis of metal organic complexes.The studies of the metal complexes synthesized by using these two kinds of ligands are mostly based on gas adsorption properties,luminescence properties,and magnetic properties,and the application research on anti-tumor activity is not yet sufficient.Objective In this present article,we first briefly introduced the current treatment methods of hepatic carcinoma and the structure,synthesis methods,classification,performance,especially anti-tumor activity of metal complexes,and mainly introduced the classification and anti-cancer mechanism of anti-cancer metal complexes.Then the basis and research content of this study was introduced.In this paper,two novel metal complexes were synthesized by solvothermal method.The first metal complex is a trinuclear magnesium complex with 1,3,5-benzenetrisbenzoic acid as the ligand.The second one is a trinuclear zinc metal complexes with 1,3,5-benzenetrisbenzoic acid and imidazole as mixed ligand.The composition and structure of the complexes were characterized by elemental analysis and infrared spectroscopy,and the crystal structures of the two complexes were determined by X-ray single crystal diffraction analysis.The in vitro and in vivo antitumor activities of these two metal complexes were then studied.Firstly,the cytotoxicity of these two metal complexes on hepatic carcinoma cells was studied at the cellular level using MTT assay.The effect of metal complexes on apoptosis was investigated by flow cytometry.Then the toxicity and anticancer activity of the metal complexes were analyzed on an orthotopic mouse hepatoma model,and the expression of apoptosis-related proteins was detected using protein western blot.Based on the above studies,a novel metal complex with good anti-tumor activity and tumor cell specificity was identified,which provided the research basis and theoretical basis for its application in the treatment of liver cancer.Method Part one Synthesis and Crystal Structure a Novel Mg(Ⅱ)-based Metal Complexes A trinuclear magnesium complex with 1,3,5-benzenetrisbenzoic acid as the ligand was synthesized using the solvothermal method,namely {[Mg3(BTB)(DMA)4](DMA)2}n.The composition and structure of the complexes were characterized by elementalanalysis and infrared spectroscopy,and the crystal structures of the two complexes were determined by X-ray single crystal diffraction analysis.Part two Synthesis and Crystal Structure a Novel Zn(Ⅱ)-based Metal Complexes A trinuclear zinc metal complexes with 1,3,5-benzenetrisbenzoic acid and imidazole as mixed ligand,namely {(H2NMe2)2[Zn3(BTB)2(OH)(Im)](DMF)9(Me OH)7}n.The composition and structure of the complexes were characterized by elemental analysis and infrared spectroscopy,and the crystal structures of the two complexes were determined by X-ray single crystal diffraction analysis.Part three Anti-Hepatic Carcinoma Activity of Two Novel Mg(Ⅱ)-based and Zn(Ⅱ)-based Metal Complexes On the basis of the first two parts,the in vitro and in vivo anti-tumor activity and toxicity of the two novel metal complexes that synthesized above have been investigated.Firstly,the effect of two complexes on proliferation and apoptosis of hepatocytes was studied by MTT assay and flow cytometry;then an orthotopic tumor model of hepatocellular carcinoma in mice was established to study the in vivo toxicity and antitumor activity of the two metal complexes.The expression of apoptosis-related proteins in mouse tumor tissues was detected by western blotting to explore the antitumor mechanisms of the two novel metal complexes.Results Part one Synthesis and Crystal Structure a Novel Mg(Ⅱ)-based Metal Complexes Mg(Ⅱ)-based Metal Complex contains a linear [Mg3(COO)6] cluster that connected by the fully deprotonated BTB3-ligands to give a kgd-type 2D bilayer structure.Part two Synthesis and Crystal Structure a Novel Zn(Ⅱ)-based Metal Complexes Zn(Ⅱ)-based Metal Complex represents a microporous 3D pillar-layered system based onthe binuclear Zn units and pillared Im ligands,which shows a(3,5)-connected hms topological net.Part three Anti-Hepatic Carcinoma Activity of Two Novel Mg(Ⅱ)-based and Zn(Ⅱ)-based Metal Complexes MTT results showed that Mg(Ⅱ)and Zn(Ⅱ)irons and H3 BTB and Im ligands had very little toxicity to hepatoma cells and normal hepatocytes(IC50 > 100 μM),while the two metal complexes had higher cancer cells toxicity with an IC50 of 20-35 μM,which was comparable or even lower(25-40 μM)than carboplatin,suggesting that metal complexes have varying degrees of toxicity to hepatoma cells.In addition,the toxicity of the two metal complexes on liver cancer cells was significantly higher than that of normal liver cells,indicating that the two newly synthesized metal complexes have tumor cell specificity.In contrast,the chemotherapy drug carboplatin has high cytotoxicity on these five cell lines,and its activity is not tumor selective.We used SMMC-7721 hepatoma cells for Annexin V-FITC/PI double staining to detect apoptosis,and found that both Mg(Ⅱ)metal complexes and Zn(Ⅱ)metal complexes promoted apoptosis of SMMC-7721 hepatoma cells,which was similar to the anticancer drug carboplatin equivalent.During the treatment of the in situ hepatic tumor mouse model,the body weights of Mg(Ⅱ)metal complex,Zn(Ⅱ)metal complex and carboplatin group were decreased firstly,and then the body weight of Zn(Ⅱ)metal complex group recovered slowly.The body weight of the Mg(Ⅱ)metal complex group and carboplatin group continued to decline.After the treatment,the body weight of these two groups was significantly lower than that of the Zn(Ⅱ)metal complex group(P < 0.05).In addition,during the treatment,the mental state and activity of mice in the Zn(Ⅱ)metal complex group were good than that of the Mg(Ⅱ)metal complex and the carboplatin group.After thetreatment,all the mice of the control group died.The death rates of the Mg(Ⅱ)metal complex,the Zn(Ⅱ)metal complex,and the carboplatin were 60%,10%,and 40%,respectively.The above results indicated that the toxicity of the Zn(Ⅱ)metal complex is lower than that of the Mg(Ⅱ)metal complex and carboplatin.After treatment,the tumor weights of the Zn(Ⅱ)metal complex and the carboplatin were significantly lower than that of the Mg(Ⅱ)metal complex(P<0.05).The tumor weight of the Zn(Ⅱ)metal complex was less than that of the carboplatin group,however,there was no significant difference between the two groups(P>0.05).This indicated that both the Mg(Ⅱ)metal complex and the Zn(Ⅱ)metal complex had antitumor activity in vivo,and the antitumor activity of the Zn(Ⅱ)metal complex is higher than that of the Mg(Ⅱ)metal complex and similar to the chemotherapeutic drug carboplatin.Subsequently,we detected the expression of apoptosis-related proteins in mouse tumor tissues by western blotting to explore the antitumor mechanisms of the two novel metal complexes.Compared with the control group,the expression levels of the anti-apoptotic protein Bcl-2 of the Mg(Ⅱ)metal complex and the Zn(Ⅱ)metal complex were down-regulated,while the expression level of the pro-apoptotic protein Bax was up-regulated,and the Bax/Bcl-2 ratios of the two metal complexes were significantly increased.This leaded the increases of mitochondrial membrane permeability and release of anti-apoptotic proteins.Cyt-c and Caspase-3 and Caspase-9 expression were also increased.Therefore,Mg(Ⅱ)metal complexes and Zn(Ⅱ)metal complexes can promote mitochondrial release of Cyt-c by regulating the expression of Bcl-2 family proteins,thereby activating caspase family proteins and inducing apoptosis of tumor cells.Conclusion In summary,we synthesized two novel metal complexes using the easily and efficientlysolvothermal method in this study.One showed a kgd-type 2D bilayer structure and the other a(3,5)-connected hms topological net.Both metal complexes have liver cancer cell toxicity in vitro.We found that Zn(Ⅱ)metal complexes had stronger anti-tumor activity than Mg(Ⅱ)metal complexes and was less toxic in the in vivo studies.The antitumor effects of the two metal complexes were related to the regulation of tumor apoptosis-related proteins.