The Study On Small Molecular Compounds As Copper Ion Chelator And G-quadruplex Stabilizer

With the increasing number of AD?Alzheimer's disease,AD?patients in the world,the economic and social problems are becoming more and more serious.The formation of senile plaque?SP?caused by extracellular deposition of amyloid-?peptide?A??is the main cause of the disease.AD is not a simple single gene disease,and the occurrence and pathological changes of AD are not caused by a single cause,so the strategic drugs designed for a single target can not fundamentally solve the problem.We should look for the solutions that can act on multiple related targets of the disease at the same time.Based on this,the work direction of this paper is mainly divided into the following two aspects.Firstly,due to the diversity of A?and Cu²⁺in the pathogenesis of AD,we strategically designed and synthesized a modified compound EDTA-ASA.It is modified with classical chelating agent EDTA as core skeleton and 4-ASA as fluorophore.EDTA-ASA has multiple coordination centers,so it can provide good coordination sites and has the potential of specific chelating Cu²⁺.The targeted products were characterized by electron spray mass spectrometry?ESI-MS?,Fourier transform infrared spectroscopy?FT-IR?and nuclear magnetic resonance?NMR?.The spectral properties of the interaction between different common metal ions and EDTA-ASA were investigated using fluorescence spectroscopy?FS?and UV-vis spectrophotometry?UV-vis?.The recognition mechanism and fluorescence quenching principle were further studied by DFT theoretical calculation.The effect of EDTA-ASA on the depolymerization of A?₄₀-Cu???/Zn???aggregates induced by Cu²⁺was studied by Th T fluorescence spectroscopy and scanning electron microscope?TEM?.The results show that EDTA-ASA can specifically recognize of Cu²⁺for the obvious fluorescence quenching response,without the influence of other competitive metal ions,and the fluorescence quenching rate is up to 99.2%.The depolymerization rate of EDTA-ASA to A?₄₀-Cu???aggregates is 62.20%,which is 1.37 times higher than that of EDTA.Therefore,EDTA-ASA can effectively capture the Cu²⁺from A?₄₀-Cu???fibrotic aggregation system and play the role of depolymerizing A?₄₀-Cu???fiber aggregates.The functionalized EDTA-ASA proposed a new strategy for the design of new metal chelating agents,broadened the ways of functionalization of chelator,and opened up a new direction for AD chelator.Secondly,?-secretase is a key enzyme in the formation of A?,and the activity of?-secretase is regulated by BACE1.We can reduce the production of A?from the source by inhibiting the activity of BACE1.There is a high GC sequence region in the promoter region of BACE1 gene,and the G-rich sequence has the potential to form the secondary structure of G-quadruplex.The formation of G-quadruplex in the promoter region of BACE1 gene is expected to down-regulate the expression of BACE1,thus reducing the probability of A?production by amyloid pathway via APP.Therefore,the discovery of small molecular compounds that can induce G-rich sequences in BACE1 gene to form G-quadruplex and can specifically interact with this G-quadruplex structure may hopefully inhibit the expression of BACE1,thus inhibiting the production of A?.Based on the design strategy of G-quadruplex small molecule ligands,a series of polypyridine Ruthenium???complexes were designed and synthesized,and the target products were characterized and analyzed by ESI-MS,FT-IR and¹H NMR.The optical properties of a series of polypyridine Ruthenium???complexes were studied by UV-vis and FS.At the molecular level,the interaction between polypyridine Ruthenium???complex and BACE1 DNA sequence was studied by UV-vis spectroscopy and CD spectroscopy.