Study On Secondary Metabolites Of C.globosum From Endophytic Strain

Endophytes have some advantages, such as renewability, short growth cycle, metabolism and breeding easily to be controlled and so on. During a long term process of co-evolution with the host plant, endophytes formed a special metabolic pathway, which could produce secondary metabolites with a variety of bioactivites and structures. Therefore, screening lead compounds from endophyte secondary metabolites and studying on modification and optimization of the structures became an effective approach in developing new drugs.Chaetomiun globosum IFB-WQ was an endophyte separated from Imperata cylindrical by institute of Functional Biomolecules, Nanjing University. Previous research had showed that there are abundant cytochalasin compounds in the extract of solid culture of C. globosum that aim to provide lead compounds for the development of new drugs. Then chemical constituents of solid culture of this strain had been carried out in the dissertation. EtOAc extract and n-butyl alcohol extract of strain IFB-WQ were chromatographed on silica gel column and several different polar mixtures was obtained. Guided by 1H-NMR spectrum and TLC, further separation and purification was performed using several methods such as silica gel column chromatography, Sephadex LH-20 gel column chromatography,HPLC etc. Finally, seven compounds had been obtained and structures of them were determined by modern spectrum technology such as HR-ESI-MS, 1D and 2D NMR and comparing with references. Compounds 1-7 were identified as N-benzoylphenylalaninyl-N-benzoylphenylalaninate (1), dihydrocytoglobosin D (2), chaetoglobosin F (3), cytochalasin A (4), chaetoglobosin E (5), uracil (6) and 5-methyluracil (7), in which compound 2 had not been reported yet. In vitro cytotoxicity to human cervical cell line HeLa and human gastric cancer cell line HEPG2 of compounds 1,3,4 and 5 were evaluated by MTT. The results showed that compound 3,4 and 5 displayed moderate inhibitory activity against HeLa cells with an IC50 value of 32.47,51.7 and 7.2μg/ml respectively, while the IC50 value of positive control cisplatin was 6.42μg/ml. Compounds 3,4 and 5 obviously could inhibit proliferation of HepG2 cells with an IC50 value of 14.45,7.33 and 3.60μg/ml respectively, while the IC50 value of positive control cisplatin was 4.90μg/ml. In addition, AchE inhibitory activity of compound 3 was tested using modified Ellman method. Compound 3 had moderate AchE inhibitory activity with EC50 value of 7.06mg/ml and the EC50 value of positive control tenakrin was 0.7μg/ml.According to the idea of discovering and developing lead compounds from special environment microorganism, looking for lead compounds from special environment microorganism-endophyte C. globosum was conducted in this dissertation. Several bioactive compounds had been found through our research, which several compounds for further research.