Hypoxic Fluorescent Probe Base On Flavonoids: Design, Synthesis And Properties

Hypoxia is a important characteristic of tumor microenvironment. The hypoxic cells insolid tumor result in tumors having strong resistance to radiotherapy, chemotherapy, et al. Atthe same time, hypoxic cells are the reason for local recurrence and malignant metastasis. Sothe detection for hypoxic regions has practical significance. Fluorescence probe has highsensitivity, therefore, the method of fluorescence imaging becomes a research hotspot.3-hydroxyflavone have many optical characteristics, for example a large Stokes shiftvalues, good light stability, high quantum yield, et al. In this thesis, nitrobenzene andnitroimidazole are the hypoxia response groups of hypoxic and3-hydroxyflavone derivativesare fluorophore. Base on the two parts, the text designed and synthesized a series offluorescent probes to detect hypoxic. Due to nitro has strong quenching effect forfluorescence, resulting in the fluorescence of fluorescent molecule was weakened. In tumorhypoxia cells, when nitro-compound having electron affinity through panniculus adiposus ofhypoxia cell, because of the action of the nitroreductase and triphosphopyridine nucleotidereduced tetrasodium salt（NADPH), the nitro group can be reduced to the amino group, afterelectron transfer reaction, break with the fluorescent molecule, releasing the fluorescentmolecule, thereby realizing the detection of hypoxic regions. However, with the introductionof hypoxic response group containing nitro, the water-soluble of probes greatly reduce,therefore, by introducting two side chains including morpholine ring, the water-soluble ofprobes were increased. And because of the introduction of the side chain, comparing withcompound5c, the emission wavelength of compound11c can reach554nm. And thestructure of the synthetic compounds were verified by NMR, HRMS and IR. Measurereduction potential by using cyclicyoltammetry, study the mechanism of probe detectinghypoxia by using HRMS, discuss the effect of types of buffer solution, pH, property andcontent of solvent for chromophre, text the cytotoxicity of probe using MTT, and apply todetect hypoxic cell by the method of fluorescence imaging.The results show that the structure of hypoxia response group affects the half-wave reduction potential, the half-wave reduction potential of13c containing nitroimidazole(-0.802V) is higher than the half-wave reduction potential of12c containing nitrobenzene (-0.802V),so the probe containing nitroimidazole is more easily reducted. The emission wavelength offluoresceny molecules5c adds to554nm from545nm due to the introducing of the sidechain including morpholino. The intensity of fluorescence molecule increases with theincreasing of pH, but is not affected by the types of buffer solution, wherein the fluorescent of11c containing dimethylamino in pH=7.8reaches five times of the fluorescent in pH=5.0.The intensity of fluorescence molecule weaks with the increasing of the polarity of cosolvent,the fluorescent of11c in tetrahydrofuran is stronger than in dimethyl sulfoxide. The intensityof fluorescence molecule increases with increasing of the amounts of co-solvents. Theprobe(10μmol/L), incubating cells for24h, did not show toxicity. The probe can be reducedin hypoxic cells, releases a fluorescent molecule, shows hypoxic selectivity. So it can be usedto detect the hypoxia.