The Synthesis And Applications Of Coumarin-7-Boronate Fluorescent Probe

Free radicals and human health have close relations, the study of antioxidant becomes more and more in recent years, fluorescence methods have the advantages of high accuracy and less interference in the determination of free radicals, many scholars of the word study the aspact. So finding more appropriate fluorescence probes used in antioxidant appears particularly important. Coumarin compounds have good fluorescence performance, fluorescence intensity has some to do with C-7 electron-donating group transferring charge intra-molecularly to carbonyl in coumarin ring lactone, all kinds of fluorescence performance can be achieved by modifying electronic groups in coumarin structure. By introducing bis(pinacolato)-diboron to C-7 in coumarin, we improve its reactivity and make it can act with hydroxyl free-radicals and superoxygen free-radicals generating strong fluorescence compounds which is 7-hydroxyl coumarin, measuring the change of the fluorescence intensity before and after reaction can be used as a method of the determination of oxygen radicals. The aim of this experiment is to synthesize a new fluorescent probe which is used in vitro antioxidant study and to look for a new more appropriate fluorescent probe. In a word, a new method for antioxidant research was provided.ObjectivesTo synthesize 7-boronic acid pinacol ester coumarin its structure by some analysis methods, investigate its fluorescence properties and study the maximum absorption wavelength and various conditions'effect on the fluorescence intensity including pH, kinds of buffer solution, temperature, reaction time and so on. Its application prospect by the comparing the result of its antioxidants in vitro oxidation experiment with the traditional methods was examined.Methods1.Getting 7-trifluoro mesylate coumarin by sulfonation and generating 7-boronic acid pinacol ester coumarin by further replacement;2.7-boronic acid pinacol ester Coumarin was reacted with different radical respectively which had very good response and the influence of kinds of condition on fluorescence intensity were inspected;3. Traditional methods for determining the VitC and fungi polysaccharides compounds in vitro antioxidant capacity comparison were compared with the current method, its accuracy and sensitivity were analyzed and the advantages and disadvantages of two methods were compared;Results7-boronic acid pinacol ester coumarin was synthised and the reaction had high yield which was 78.3%. And the compound had good response to hydrogen peroxidehydroxyl radical, superoxide radical and DPPH radical; comparing with traditional methods, it had high accuracy, sensitivity and little interference when it was used in the determination of VitC and fungi polysaccharides compounds in vitro antioxidant capacity and it could be used in the antioxidation system of the 330nm excitation wavelength and the 453nm emission wavelength without fluorescence interference to investigate the ability of antioxidant and scavenging free radicals in vitro, The anti-oxidants effect of the probe used in vivo required further study.ConclusionsCoumarin-7-boronate is a water-soluble fluorescence probe reagents, and can react with a variety of free radicals to generate 7-hydroxyl coumarin which can result in strong fluorescence; comparing with traditional methods, it has high accuracy, sensitivity and little interference when it was used in the determination of VitC and fungi polysaccharides compounds in vitro antioxidant capacity and it could be used in the antioxidation system of the 330nm excitation wavelength and the 453nm emission wavelength without fluorescence interference to investigate the ability of antioxidant and scavenging free radicals in vitro.