Construction And Biological Application Of Hydrogen Peroxide-Activated Arylboronate Probes/Prodrugs

Hydrogen peroxide(H2O2)is an endogenous reactive oxygen species(ROS)mainly produced in mitochondria.Increasing studies have shown that low concentrations of H2O2 play a cruial role in immune responses and cell signaling.However,it can cause oxidative stress when H2O2 is excessive.It has been shown that many pathological tissues of ROS-related diseases have higher H2O2 concentrations than normal tissues,which provides a theoretical basis for designing probes and prodrugs for best understanding pathological process based on H2O2.Therefore,the detection of H2O2 in living cells or the design of prodrugs for targeting H2O2 have attracted increasing interest.Arylborates,including arylboronic esters and arylboronic acids,are important chemical functional groups in response to H2O2.Many studies have shown that arylborates has high sensitivity and selectivity to H2O2.Fluorescent probes designed based on cascade-intramolecular cyclization have the advantage of less interference from background fluorescence.In this paper,small molecule prodrugs and probes were designed and synthesized based on the structure of aryl boronate esters,and their subsequent biological tests were carried out.The main contents of this paper are as follows:Chapter 1.Firstly,the concept,generation and function of ROS were introduced.Some ROS-responsive fluorescent probes,prodrugs and theranostic prodrugs were summarized.Finally,the ROS-responsive fluorescent probes designed based on the cascade-intramolecular cyclization reaction are briefly introduced.Chapter 2.We reported a H2O2-responsive theranostic prodrug(CM-PPT)based on cascade-intramolecular cyclization reaction.The prodrug uses aryl boronate ester as the H2O2 recognition site,coumarin derivative as the fluorophore,and the podophyllotoxin as the active drug.The mechanism of action was verified by means of UV-vis,fluorescence and HPLC.After the prodrug interacted with H2O2,the coumarin derivative was generated through intramolecular cyclization reaction and the active drug was released.Therefore,the prodrug is expected to have a good therapeutic effect in the application of drug delivery to tumor.Chapter 3.The prodrug FI-F was synthesized by linking the flavonoid derivatives with F as both fluorophore and active drug to aryl boronate ester via ether bonds.Fluorescence test results show that the prodrug can be effectively activated by H2O2 and release flavonoid derivatives.Not only that,the release of the prodrug can also be verified by the spectral signal changes of ¹⁹F NMR.Therefore,through the combination of NMR and fluorescence,it is expected that this prodrug molecule can provide a new strategy for the antitumor prodrug platform.Chapter 4.A H2O2-responsive fluorescent probe CM-CN was designed and synthesized based on the cascade-intramolecular cyclization reaction.The probe uses aryl boronate ester as the H2O2 recognition site.The probe is almost non-fluorescent,eliminating the interference of its own fluorescent background.The response to H2O2was tested by fluorescence and other means,and the experimental results showed that the probe has good selectivity to H2O2.Chapter 5.We summarized the whole thesis,and gave study prospect for the design of H2O2-responsive fluorescent probes and theranostic prodrugs.