| Photodynamic therapy (PDT) is a new concept of the cancer treatment, which selectivelyinhibit or kill the cancer cell line through the combined application of the photosensitizer, oxygen,and visible light. There are three elements in PDT process: photosensitizer, light and oxygen. Thephotosensitizer (most of them are belong to porphyrin derivatives) plays an important role in PDT.Although several photosensitizers have been shown to be efficacious in clinical trials, most of themhave some disadvantages, which significantly hampers their clinical utility. Therefore, it is quitepressing to explore and develop new high-efficiency photosensitizers.The first part of this thesis mainly expounds the principle of the photodynamic therapy,especially the singlet oxygen in PDT process, and reviews the types and applications of variousphotosensitizers.The part II to part IV focus on the research contents of this thesis, including design, synthesis,analysis and mechanism of viarious chlorin derivatives. In order to get more effectivephotosensitizers in PDT, a series of novel chlorophyll-based chlorins were prepared by chemicalmodification of chlorophyll a and chlorophyll b, which can be concluded as follows:Methyl pheophorbide a (MPa) and methyl pheophorbide b (MPb)prepared from silkwormdroppings was used as starting material, which were chemically modified to give a series ofchlorophyll degradation products, such as methyl pyropheophorbide a (MPPa),132-hydroxylpheophorbide b methyl ester, chlorin f dimethyl ester and purpurin-18methyl ester. Furtherchemical modification of these precursors gave a series of chlorophyll-based chlorins with variousfunctional groups, including the construction of β, β-dicyanomethylene, the oxidation of3-vinylgroup, the modification of the isoylic ring E and the reaction of the7-formyl group of MPb. Thegeneration mechniams of some new compounds were also discussed. The structures of all the newcompounds were characterized by1H NMR, UV-Vis and IR spectra. |
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