Design,Synthesis And Application Of The Novel Monoamine Oxidase Probes

Monoamine oxidases are a family of enzymes bound to the outer membrane of mitochondrial in almost all organizations of vertebrate.It plays an important role in the metabolism of neurotransmitters.The activity of monoamine oxidase is closely associated with many diseases,such as Alzheimer’disease,Huntington’s disease,Parkinson’s disease,normal aging and so on.Therefore,it is significant to seek an efficient,accurate,convenient and safe method in biomedical and scientific research.Fluorescent probes,in comparision of traditional detection method,have the advantages in high sensitivity,good selectivity,and a small amount of sample,and thus,has been widely used in analytical chemistry,biochemistry,medicine,clinical diagnosis,environmental science and other fields.This paper designed and synthesed a series of fluorescent probes based on the catalytic mechanism of monoamine oxidase.They had good selectivity towards MAO.The following are the three aspects of this thesis:(1)We designed and synthesized four on-off probes based on the principle of β-elimination,that the fluorescent reporter was fluorescein.Upon treatment with MAO,these probes underwent oxidation andβ-elimination to liberate fluorescein-methyl ester.Through studying for the enzyme reaction kinetics,we found that the probes not only had a high sensitivity for monoamine oxidase but also a good selectivity on monoamine oxidase B.(2)Using the principle of fluorescence resonance energy transfer(FRET),we designed and synthesized two probes that 3-aminopropoxy group and 1-methyl-1,2,3,6-tetrahydropyridin group were regarded as the substrate of monoamine oxidase,5(6)-carboxyfluorescein and Cy3 were as donor and acceptor respectively.After reaction with the monoamine oxidase,the results showed that the two probes could detect monoamine oxidase successfully.And further more,the selectivity towards monoamine oxidase B of the probe that 1-methyl-1,2,3,6-tetrahydropyrid in was as the substrate was superior to the one whose recognition group was propylamine.(3)In the same way,we designed and synthesized two probes,using 7-hydroxyl-4-acetic acid coumarin and 5(6)-carboxyfluorescein for donor and acceptor of FRET system separately,and 1-methyl-1,2,3,6-tetrahydropyridin group as the substrate of monoamine oxidase.However,the results showed the fluorescent intensity did not change at 530 nm after reaction with MAO.The reason may be that the distance between the two fluorophores was so close that the fluorescence quenching phenomenon was generated.In conclusion,the article synthesed 8 probes,there were six probes could be used to measure the activities of MAO and had a good selectivity,sensitivity towards MAO-B.