|其他摘要||Bioactive natural products from endophytic fungi have enormous potential as the source of new medicine. In this thesis, the endophytic fungi from Maytenus hookeri were studied and their antimicrobial constituents against Mycobacterium tuberculosis were identified. The endophytic fungi were cultivated on PDA medium after activation. They were phylogenetically identified through analyses of morphological characteristic traits combined with nucleotide sequence of internal transcribed spacers (ITS). Their antimicrobial activities were examined with crude extracts via disk diffusion bioassay against microbes of Staphylococus aureus, Mycobacterium tuberculosis, Candida albicans, Saccharomyces ceevisiae, Penicilium avellaneum UC-4376. Results showed that 24 strains of the endophytic fungi from M. hookeri could be classified to be 14 genera (Penicillium, Aspergillus, Verticillium, Trichoderma, Alternaria, Arthrinium, Fusarium, Hirsutella, Chaetomium, Xylaria, Diaporthe, Phomopsis, Botryosphaeria, Colletotrichum) of 9 families (Moniliaceae, Dematiaceae, Tuberculariaceae, Clavicipitaceae, Chaetomiaceae, Xylariaceae, Diapothaceae, Sphaeropsidaceae, Melanconiaceae) of 5 orders (Moniliales, Hypocreales, Xylariales, Sphaeropsidales, Melanconiales). In addition, most of the antimicrobial strains belonged to Moniliales. Crude extracts from Ly50' (Chaetomium), Lr82 (Trichoderma) and Lr417 (Fusarium) fermentation significantly inhibit the growth of M. tuberculosis. Ly50' and Lr82 were therefore incubated on 10L solid-state PDA medium for further study, respectively. Based on bioassay-guided fractionation, chaetoglobosin B from Ly50' was determined as the potent component against M. tuberculosis. The constituents against M. tuberculosis in Lr82 were analyzed as lipopeptides.
Bioassay-guided fractionation mentioned in the thesis may give a explicit target towards the bioactive constituents. If more targets are given, more valuable active constituents can be separated efficiently through an appropriate high-throughput screening. It is believed that the application of bioassay-guided fractionation might enlighten the access to the natural products.|