|其他摘要||The initiative of this dissertation was to search for new bioactive secondary metabolites from endophytic fungi of medicinal plant. On the basis of bioassay results, endophytes cultivated on Camptotheca acuminate and Maytenus hookeri were used as experimental material, and research works were carried out on the isolation, identification and activity detection of chemical components from cultured fungal endophytes and co-cultured endophytic fungi with plant cells. The main findings are as follows.
More than forty compounds, including eighteen new ones, were obtained from the cultures of four endophytic fungi on C. acuminate and M. hookeri. Their structures involved terpenoids, polyketides, alkaloids and ergosterols, and some of them were bioactive. Concretely, 14 compounds comprising a new monoterpernoid and eight new polyketides were isolated from the liquid cultured endophyte Diaporthe sp. XZ-07 of C. acuminate, and compound 11 showed moderate cytotoxicity against human cancer Hela cells and antibacterial activity against Shigella dysenteriae. The investigation on secondary metabolites of endophytic fungal strain Botryosphaeria species MHF of M. hookeri, incubated on potato-dextrose-agar and Murashige-Skoog media, resulted in the isolation of five new terpenoids, botryosphaerins A-E (1-5), including four tetranorlabdanes and a labdane-type diterpene, together with fifteen known compounds. Among them, only compound 12 showed the similar inhibitory zones against Candida albicans and Saccharomyces cerevisiae as the positive control, nystatin. From solid cultures of endophyte Phomopsis species Lz42 of M. hookeri, a new sesquiterpenoid, 4-deacetyl-10-oxo-dihydrobotrydial (1), and a new sterol, 22E,24R-5α,8α- epidioxyergosta-6,22-dien-3β-formate (2), were isolated together with five related known compounds. We also studied the chemical constituents of endophytic fungal Colletotrichum sp. Ly22 from M. hookeri and gained 4 compounds, including a new sesterterpenoid and a new alkaloid.
To study the interactions between endophytes and their host plants, the co-culture of Alternaria alternata Ly83, one of endophytic fungi cultivated on M. hookeri, and callus of M. hookeri was established on the basic principle of chemical defense. The chemical study of the solid cultures and co-cultures of A. alternata led to the isolations of 26 compounds, including 9 new mixed terpenoids and a new polydetide. Based on the results, complementary experiments for co-culture were performed. In addition, 16 known compounds, mainly consisted of terpenoids and sitosterols, were isolated from the callus of M. hookeri.
In the last part of this dissertation, a review covers 106 literatures until 2008 and 173 bioactive compounds isolated from plant endophytic fungi were presented.|