Preparation Of Albumin Metal Complex And Its Scavenging For Oxygen Free Radicals

When the living organism is in a normal state,the production and elimination of free radicals in the body are in a state of balance and will not cause harm to the living organism.However,due to the outside interference of the excessive free radicals in the body lose their balance,which will destroy the structure and function of cells and cause harm to the human body.Superoxide dismutase（SOD）is the most important enzyme in the balance of superoxide anion free radical(O₂^·-)in the body,which can protect the tissues from oxidative damage and maintain free radical balance in the body.However,the application of SOD is limited by the difficulties in extracting SOD and the high price.It is the focus of current research to search for low cost and better analog drugs to scavenge oxygen free radicals.Therefore,a series of bovine serum albumin metal complexes were designed and synthesized in this paper.The scavenging performance of albumin metal complexes on oxygen free radical(O₂^·-)was investigated by NBT photoreduction method,so as to simulate superoxide dismutase（SOD）.This thesis mainly consists of four parts:Chapter 1:This chapter mainly introduces the research progress of superoxide dismutase（SOD）scavenging oxygen free radicals and protein metal complex simulating SOD enzyme.The interaction patterns between small molecule drugs and proteins are summarized.The main research content and significance of this paper are described in detail.Chapter 2:Two ligands of 7-methoxychromone-3-aldehyde-（o-hydroxynaphthoyl）hydrazone（L₁）and 2-hydroxy-4-diethylamino-benzaldehyde-（o-hydroxynaphthoyl）hydrazone（L₂）and metal complex（L₁M and L₂M）were synthesized.The ligand was synthesized from paeonol,4-diethylamino salicylaldehyde and 3-hydroxy-2-naphthalene formhydrazide with trichlorophosphate as catalyst through the condensation reaction of hydroxyaldehyde.The metal complexes corresponding to the two ligands were further prepared.The ligands and their complexes were characterized by ¹H NMR,Elemental analysis,FT-IR,Uv-vis and Fluorescence spectrophotometry.The results showed that the ligands（L₁ and L₂）coordinated with the four metal ions at 1:1.Chapter 3:Designs and synthesis of a series of albumin metal complexes（BSA-L₁M and BSA-L₂M）.The interaction between metal complexes and BSA was studied by Uv-vis and fluorescence spectrophotometry.The stern-Volmer and Vant-Hoff equations were used to calculate the thermodynamic parameters of the interaction between the metal complex and BSA.According to the results of two kinds of metal complexes with BSA is coordination effect.At the same time,the thermodynamic parameters L₁M interact with BSAΔH﹥0 andΔS﹥0 is a typical hydrophobic force and the L₁M with BSA binding site is located in the binding site II;Thermodynamic parameters of L₂M interaction with BSAΔS﹥0 andΔH﹤0,belongs to the typical electrostatic gravity,L₂M and BSA binding sites of the binding sites I.The circular dichroism spectrum results show that,compared with the original BSA,theα-helix content of BSA-L₁Cu is reduced from 52%to 49.46%and theα-helix content of BSA-L₂Ni,BSA-L₂Cu,BSA-L₂Fe and BSA-L₂Zn is reduced from 52%to 51.05%,50.68%,50.32%and 49.76%respectively.It shows that the metal complex（BSA-L₁M和BSA-L₂M）interferes with the secondary structure of BSA,but it has little effect.Chapter 4:The scavenging performance of BSA-L₁M and BSA-L₂M on superoxide anion radical(O₂^·-)was investigated by NBT photoreduction method and the semi-maximum effect concentration(EC₅₀)was determined and compared with the natural SOD enzyme.The results showed that BSA-L₁Cu had the strongest scavenging activity,EC₅₀ was 0.22 and the simulation was 18.64%.The scavenging activity of BSA-L₂Zn was 0.18 in EC₅₀ and the simulation degree was 22.8%.In conclusion,the two kinds of albumin metal complexes（BSA-L₁M and BSA-L₂M）prepared in this paper have obvious oxygen free radical scavenging ability and the superoxide dismutase（SOD）simulants with high water solubility and biocompatibility were obtained.The results shown that expected to be applied to health care products,cosmetics,drugs and biomedical materials.