Study On Antitumor Activity Of Natural Products Derived From Plant Endophytic Bacteria

The successful development of derivatives of paclitaxel and camptothecin showed that the process of developing innovative drug is actually a repetitive process of finding and developing lead compounds. Due to the limit of resources from animal and plant, researchers began to pay much attention (eg:marine microorganisms, endophyte) to look for anti-cancer lead compounds from secondary metabolites of microbes living in the special environment. In the long-term coevolution process with host, microbe living in the special environment had formed special metabolic pathways which could provide a rich source of compounds for developing anti-cancer drugs.In vitro cytotoxicity of compounds from severe endophytes were studied in this dissertation. MTT method was used for cytotoxicity screening. The testing tumor cell lines were human hepatoma cell lines SMMC-7721and human cervical carcinoma cell lines HeLa and cisplatin was used as a positive control. The results showed that Penochalasin C (7)、ShJ-LLY-GUXI-2(13)、N-methyl-1H-indole-2-carboxamaide (19) and12’-hydroxy isororidin E (22) could significantly inhibited the growth of SMMC-7721cell lines with with IC50values of35.4,8.5,38.0and6.3μg/ml respectively. Chaetoglobosin F (5)、Chaetoglobosin E (6) and Ditryptophenaline (17) showed weak cytotoxic with with IC50values of49.2,51.7and62.3μg/ml respectively. Penochalasin C (7), ergosterol (9), ergosterol-5,8-peroxide (10), ShJ-LLY-GUXI-2(13) and12’-hydroxy isororidin E (22) significantly inhibited the growth of HeLa cells with with IC50values of49.3,23.6,26.5,6.0,2.5μg/ml respectively. ChaetoglobosinF (5) and N-methyl-1H-indole-2-carboxamaide (19) had weak activity against HeLa cells with IC50values of52.7and60.2μg/ml respectively.Effect of N-methyl-lH-indole-2-carboxamaide (19) and12’-hydroxy isororidin E (22) on SMMC-7721and HepG-2cell lines proliferation were also studied in this dissertation. SMMC-7721and HepG-2cells were treated with different concentrations (0.01,0.1,1,2and10μg/ml) of19and22for a certain time (6,12,24,48and72h). The results showed that19and22could inhibit SMMC-7721and HepG-2cell growth in time-dependent and dose-dependent manner.The cell cycle analysis indicated that19could delay SMMC-7721and HepG-2cells in S phase weekly, whereas22could induce SMMC-7721and HepG-2cells in G1phase arrest. Western blot showed that the expression of cell cycle negative regulation protein p27were up-regulated by19and22respectively, which might be led to the arrest of cell cycle and growth inhibition of SMMC-7721and HepG-2cells.In addition, the influence of19and22on apoptosis of SMMC-7721and HepG-2cells was studied by detecting apoptosis-related protein through western blot. It was found that19and22could induce the cleavage of PARP, which meant that both19and22could induce apoptosis of SMMC-7721and HepG-2. Molecular mechanisms of cell apoptosis will be studied in further research.Tumor development is found to closely associatted with cell proliferation and cell apoptosis. Effects of19and22on proliferation inhibition and induced-apoptosis of SMMC-7721and HepG-2cells was studied in this dissertation, and prelimilary anti-cancer mechanism of19and22was also explored, which provide an important experimental basis for the developing new anti-tumor drugs.