Screening Of Porphyrin-typed Photodynamic Therapeutic Compounds

Cancer is a worldwide serious problem. Traditional methods of cancer therapy are surgical excision?radiotherapy and chemotherapy. Photodyna-mic therapy (PDT)is a newly developed approach of curing cancer, which is based on three nontoxic elements:photosensitizers, oxygen and laser. Photosens-itizers are dyes that preferentially uptaken and retained by tumor tissues. The mechanism of PDT is each photosensitizer excited by light at an appropriate wavelength and transfer the energy to oxygen in tissue leads to the generation of cytotoxic species such as reactive singlet oxygen;this results in the irreversible destruction of tumor tissues. Crucial element of PDT is photosensitizer. Rapid development of PDT requires novel type of photosensitizers,our own lab synthesized 2 totally new type of photosensitizers and compound X. Based on the model of HepG2 cell line(hepatoma) and two different kinds of gastric cancer cell lines——MGC803 and HGC27, systematic experimental research was performed to evaluate the photodynamic therapeautic efficiency and related mechanisms of our compounds.4 experimental groups was designed, which are blank control group (no compounds, no light), compound control group(only compounds,no light), light control group(no compounds,only light) and experimental group(with compounds and light at the same time). Photobleaching experiemnt was done to evaluate the photostability of compounds upon repititive ilumination; fluorescent microscopy picture was recorded to observe whether our compounds entered into three tumor cells or not;and detect the uptake amount was measured based upon the differenc between medicine treatment berfor and after; MTT and CCK-8 assay were used to decide survival rate of tumor cells after PDT;subcellualr localization of compounds in HepG2?MGC803 and HGC27 (mitochondrion and lysosome) were detected under confocal laser microscopy.Photobleaching demonstrated compounds A(1-8), B(1-6) and compound X all have good stability to light illumination, whose maximal wavelength absorption all almost did not declined after repetitive laser illumination. Experimental results of chapter one showed compounds A(1-3) could be uptaken by HepG2 cell, compounds A(1-4) by BGC823 cell and all of them localize into lysosomes of two tumor cells. The left compounds in A serie could not be uptaken by two tumor cell lines. Upon illuminati-on, compounds uptaken by tumor cells could produce significant PDT therapeutic effects, and among of them compound Al had the strongest efficacy and the largest uptaken amount in two tumor cell lines. While compounds which can not be uptaken by tumor cells did not produce PDT efficacy. Except compounds A7 and A8, all left A series compounds did not show dark cytotoxicity. The most effective compound Al which had been screened out had strong PDT action on HGC27 and MGC803 cell lines as well, and had no dark cytotoxicity, shows good being-uptaken ability and localized in lysosomes of HGC27 and MGC803 cell lins in both cases.Experimental results of chapter two showed B series compounds B(l-6) could be uptaken by MGC803?HGC27 and HepG2 cell lines and all localized into lysosomes of three tumor cell lines. Upon illumination, compounds B(1-6) all showed strong PDT therapeutic effects on HGC27 and HepG2 cell lines and only compounds B5 and B6 could produce PDT efficacy on MGC803 cell line. Sequence of PDT efficacy of compounds B(1-6) on MGC803?HGC27 and HepG2 cell lines were comparable and in the orders B5?B6>B1?B2 >B3?B4. In B series all compounds B(1-6) did not show dark cytotoxicity. Results of uptake experiment demonstrated compounds B5 and B6 had the largest uptake in three tumor cell lines, B1 and B2 were ranked secondly, B3 and B4 is the lowest. Considering the PDT efficiency of all of these compounds raised with the concentration and finally reach the plateau while the cellular uptaken keep raising with concentration at the same condition,and different compounds shows different being uptaken amount and different PDT efficiency. The above summary fact implys that there is a threshold for each compound PDT, before which PDT efficiency raisied with concentration. Experiemnt shows compound X had strong PDT action on HGC27 and MGC803 cell lines as well, and had no dark cytotoxicity, good uptaken ability and localized in lysosomes of HGC27 and MGC803 cell lines.