Preliminary Study On The Synthesis And Characterization Of The MRI Probe Which Is Response For Peroxidase

Objective:1.To synthesize and characterize a novel molecular MRI probe with higher relaxation efficiency which can response to the peroxidase;2.To preliminarily explore the effect of the MRI molecular probe on the response of Peroxidase at the cell level.Method:1.The ligand Tyr-EDTA was synthesized from tyrosine with multi-steps,and then complexed with Mn²⁺to form[Mn?Tyr-EDTA?].The ligand and intermediate compounds were characterized by ¹H-NMR and Mass spectrum;2.In the buffer solution,the relaxation study was performed according to the different proportion of[Mn?Tyr-EDTA?],peroxidase?horseradish peroxidase,HRP?and H₂O₂.The effects of the way of H₂O₂added in according to a certain proportion in the conditions of[Mn?Tyr-EDTA?]were also studied at different activity units peroxidase.Results:In presence of peroxidase,[Mn?Tyr-EDTA?]can form oligomer though radical polymerization which can more effectively affect the relaxation of water molecules,and the relaxation efficiency is significantly increased.At the same time,the activity of fixed peroxidase units,the proportion of[Mn?Tyr-EDTA?]and H₂O₂ and the way of H₂O₂ added in were studied in detail.When the peroxidase activity is 500 U and[Mn?Tyr-EDTA?]:H₂O₂=1:8 with H₂O₂ added in propotionly less than 1.0eq to[Mn?Tyr-EDTA?]each time,the above phenomenon is more obvious.(0.47 T,32?;[Mn?Tyr-EDTA?]:H₂O₂=1:8,oligo-[Mn?Tyr-EDTA?]:r₁=12.86 mmol^-1s^-1,r₂=16.09 mmol^-1s^-1;[Mn?Tyr-EDTA?]:r₁=4.62 mmol^-1s^-1,r₂=6.27 mmol^-1s^-1).Conclusion:The small molecule contrast agent[Mn?Tyr-EDTA?]with phenolic hydroxyl group as electon donor can reacted with H₂O₂ under the action of peroxidase to form oligomers with free radical oligo merization and increase the relaxation efficiency.The above mentioned novel contrast agent is expected to be used for the evaluation of the level of peroxidase in the body and has important clinical significance.