Synthesis And Fluorescence Properties Study Of Diphenyl Ketene Analogues

It is well-known that fluorescent probes owning preferential properties such as high sensitivity, non-destructivity, specificity and timecontrollability had been widely used in analytical chemistry, bioanalytical chemistry, medicine and cellular biology, especially in the life sciences. Fluorescent probe technology was widely used in many fields, especially in Protein-Gene engineering, which made fluorescent probe techniques to be the hot research topics.In this study, seventy compounds were designed and synthesized based on curcumin, which was an eatable pigment with low toxicity and wildely medical and pharmacal activity. The distyryl ketone structure contained in those compounds was ordered as a "fluorophore". Further more, the conversion between keto form and enli form in ketene structure colud provide special optical properties. Since those compounds were derived from nature product curcumin, they also had the low toxicity.The studies of fluorescence properties of compounds mainly included the fluorescence response of compounds to pH values, tyrosinase and BSA. The main research works and results were sumerized as follows:1) Synthesis of compounds containing diphenyl ketene structureIn this paper, seventy compounds were synthesized with substituted benzaldehyde and ketone by aldol condensation under alkaline conditions. The structure was characterized by’H-NMR and MS.2) Fluorescent response of diphenyl ketene analogues to pH valueThe UV-absorption spectra and fluorescence spectra of compounds were investigated in different pH values. The results indicated that UV-absorption spectra and fluorescence spectra were strongly dependent on pH values. The maximum absorption peaks of absorption spectra of compounds were red shifted, while the environment changed from acidity to alkalinity, which made the solution of compounds undergo a distinct color change. Fourther more, the intensity of fluorescence spectra was enhanced significantly with the increase of pH values in alkaline conditions. Those features made compounds to be used as visable pH fluorescent probes. Compounds containing the 3’-OCH3-4’-OH on benzene ring (A4, B4, C4, D4, and E4) had favorable fluorescence property.Analyzing the relationship of stucture,4’-OH on benzene ring was found to be the key group for fluorescence, and fluorescence properties improved when a methoxy was introducted at the position of ortho-phenolic hydroxyl, while bromine made the contrary. In addition, fluorescence properties of compounds with cyclopentanone searies were better than compounds with acetone, cyclohexanone, thiapyrones and pyrones searies.3) Fluorescent response of diphenyl ketene analogues to tyrosinaseThe fluorescence quenching of tyrosinase on diphenyl ketene analogs and the inhibition of diphenyl ketene analogs on tyrosinase were studied. The tyrosinase showed the function to quenching the fluorescence of compounds. Fluorescence of compounds was gradually quenchinged by tyrosinase. Amongst, compounds containing ortho dihydroxyl groups did the best. At the same time, we found compounds had the inhibility on tyrosinase. Activity of tyrosinase was gradually reduced with increasing concentrations of compounds. Compounds containing ortho dihydroxyl groups showed remarkably potent inhibitory effects on tyrosinase. The results of enzyme kinetics and Fluorescent Spectrometry could check each other.4) Fluorescent response between diphenyl ketene analogues to BSAThe fluorescence quenching of diphenyl ketene analogues on BSA were investigated. The results indicated that compounds could quench the fluorescence of BSA. The quenching constant and binding constant of compounds containing ortho dihydroxyl groups were the largest.Analyzing the relationship of stucture,4’-OH on benzene ring was found to be the major groups, the quenching constants became larger when introducting the phenolichydroxyl or bromine at the ortho-position of 4’-OH, however the methoxy could make the quenching constants smaller. The quenching constants of cyclopentanone searies were better than other searies.