Studies On Synthesis Of New Amino Acid Schiff Base Complexes And Bioactivities Of Copper(Ⅱ) And Platinum(Ⅱ) Complexes

Amino acids are the essential trace metal elements'ligands in vivo. Amino acid Schiff base complexes have been applied in a wide range of fields, such as medicine, catalysis, analytical chemistry, agriculture and so on. In recent years, many researchers reported that Schiff base complexes have the anticancer activity, but the anticancer activities and mechanisms of amino acid Schiff base complexes as proteasome inhibitors and apoptosis inducers were seldom reported. It is a challenging project to design and synthesize different amino acid Schiff base ligands and their metal complexes for studying their structures, properties and bioactivities, especially the ancicancer activity of the amino acid Schiff base copper complexes on tumor cells by targeting cellular proteasome and inducing apoptosis. Cisplatinum is a widely used anticancer drug, but it is limited because its side effects. The study of platinum complexes on tumor cellular proteasome and apoptosis may supply theoretical basis on anticancer mechanism and side effects of platinum complexes.This dissertation aims to design, synthesize and characterize new amino acid Schiff base ligands and their metal complexes. It focuses on interactions of various amino acid Schiff base copper complexes and platinum complexes with the proteasome, and their abilities to inhibit tumor cellular proteasome and induce apoptosis in vitro. Moreover, organic copper complex NC-CuCl as a model compound was used to study the antitumor mechanism of organic copper complexes. The main researches are as follows:Two Schiff base ligands which are derived from L-asparagine or L-glutamine and o-vanillin and their ten transition metal complexes have been synthesized. Their structures were characterized by IR spectroscopy, UV spectroscopy, molar conductance analysis, elemental analysis and thermal gravimetric analysis and so on. The composition of Schiff base ligand derived from L-asparagine and o-vanillin (L₁) and its five metal complexes are as follows: HL₁Li·2H₂O, [Zn(LiL₁)(CH₃COO) (H₂O)3], [CuL₁(H₂O)3], [Mn(LiL₁)(CH₃COO)(H₂O)3], [Co(LiL₁)(CH₃COO)(H₂O)3], [Ni(LiL₁)(CH₃COO)(H₂O)]·2H₂O. The composition of Schiff base ligand derived from L-glutamine and o-vanillin (L₂) and its five metal complexes are as follows: HL₂Li·H₂O, [Zn2(L₂)₂(CH₃COOH)(H₂O)₂]·(H₂O)(CH₃OH), [Cu3(L₂)₂(CH₃COO)₂ (H₂O)]·2H₂O, [Mn3(L₂)₂(CH₃COO)₂(CH₃COOH)₂]·3H₂O, [Co2(L₂)₂(CH₃COOH) (H₂O)₂]·(H₂O)(CH₃OH), [Ni3(L₂)₂(CH₃COO)₂]·5H₂O.By thermal decomposition analysis, the thermal decomposition mechanism of metal complexes has been studied. The results are as follows: The first step of the thermal decomposition kinetic function of [Mn3(L₂)₂(CH₃COO)₂(CH₃COOH)₂]·3H₂O is expressed as f(α)= 1/3(1-α)[-ln(1-α)]-2 and its kinetic equation of thermal decomposition is expressed as dα/dt = A·e-E/RT·f(α) = A·e-E/RT·1/3(1-α)[-ln(1-α)]-2. Except for the above complex, the first or second step of the thermal decomposition kinetic functions of other metal complexes derived from L-asparagine or L-glutamine and o-vanillin and transition metal are all expressed as f(α)=1/4(1-α)[-ln(1-α)]-3. Their kinetic equations of thermal decomposition are expressed as dα/dt = A·e-E/RT·f(α) = A·e-E/RT·1/4(1-α)[-ln(1-α)]-3. The kinetics parameters E and A and activation entropy changeâ–³S≠and Gibbs free energy changeâ–³G≠have been obtained.The antibacterial activities of ligands and parts of their metal complexes were also studied against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis bacteria by inhibition zone method. The antibacterial activities of tested compounds were in a concentration-dependent manner. Comparing with the ligands, their metal complexes showed higher antibacterial activity. The complexes #2 and #8 showed the higher antibacterial activity than other tested complexes and were sensitive against four tested bacteria. The best antibacterial complexes against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Bacillus subtilis were complex #8, #7, #2 and #2, respectively. The results indicate that metal complexes have higher antibacterial activities than their ligands, disclosing transition metal ions play an important role in antibacterial activity.The antiproliferaion activities of parts of metal complexes were studied by 3-[4,5-dimethyltiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT method) in human breast cancer MDA-MB-231 cells. It was found that GVC showed the higher antiproliferation activity than other metal complexes. So GVC was chose for further anticancer studies and found that GVC could inhibit proteasome activity and induce apoptosis in MDA-MB-231 and Jurkat T cells in a concentration- and time-dependent manner. Importantly, GVC could specifically and selectively inhibit proteasome activity and induce apoptosis in breast cancer MCF 10DCIS.com cells, but not in normal, immortalized human breast MCF 10A cells. These data demonstrate that the GVC could widely inhibit proteasome activity and induce apoptosis in human cancer cells. Moreover it could specifically and selectively induce proteasome inhibition and apoptosis in human tumor cells.The antitumor mechanism of organic copper complexes was studied by Image-iTTM live green reactive oxygen species detection kit used organic copper complex NC-CuCl as a model compound. This study found the inhibition of proteasome activity induced by organic copper complexes might be mainly through copper binding mechanism and induced cytotoxicity and apoptosis might be primarily through proteasome inhibition. ROS generation may be partially involved in the process of the copper complexes induced cell death, but not the major mechanism.The inhibition of purified 20S proteasome by four platinum complexes were investigated and found that their inhibition potency of 20S proteasome was in a dose-dependent manner. Their IC50 values were less than 6μM. Their antiproliferaion activities were studied by MTT method in human breast cancer MDA-MB-231 cells and found these four platinum complexes had much more antiproliferation activity than that of cisplatin. Their antiproliferation IC50 values were less than 10μM. The further study demonstrates that these four platinum complexes could inhibit proteasome activity and induce apoptosis in human breast cancer MDA-MB-231 cells. This research provides necessary theoretical data for further study on their anticancer activity in vivo.The crystal of the Schiff base derived from 4-aminoantipyrine and terephthalaldehyde belongs to monoclinic, P2(1)/C space group, molecular formula is C30H28N6O2, M=504.58. The unit cell parameter are: a = 6.0710(2)?, b = 22.2948(7) ?, c = 9.8712(3) ?,α= 90o,β= 95.147(2)o,γ= 90o, Z = 2, V = 1330.70(7) ?3, T = 293(2) K, Dc = 1.259mg/m3, R1 = 0.0494, wR2 = 0.1361 for I>2σ(I), F(000) = 532. The single crystal structure indicates that the molecule is not a two-dimensional plane, but extending to the three-dimensional space. It is the intermolecular hydrogen bond interaction to form a one-dimensional chain structure.The Geometry optimization of C30H28N6O2 was performed by the hybrid density functional theory of the B3LYP method. The energy level, electronic population in the frontier molecule orbitals of the fragments of molecules, the atoms with plentiful electron like as N, O atoms and natural atomic charges distribution were obtained. The calculation results disclose that the calculated data and the tested data of parts of the bond lengthes and bond angles are similar. While this ligand coordinates with metal ions or other molecules, N(31), N(64), O(33) and O(66) atoms could occur in certain reactions or in coordination with metal ions.The thermal decomposition kinetic function of the compound C30H28N6O2 is expressed as f(α)= 3/2(1-α)4/3[1/(1-α)1/3-1]-1 and its kinetic equation of thermal decomposition is expressed as dα/dt = A·e-E/RT·3/2(1-α)4/3[1/(1-α)1/3-1]-1, E = 1248 kJ/mol, lnA = 235.1, r = 0.9799,ΔS≠= 1888 J/mol·K,ΔG≠= 86.14 kJ/mol.