Study On The Secondary Metabolites From Two Endophytic Fungi

Microorganism features a type of species, a short growth period, diverse and manageable metabolic process and has been investigated to produce lots of secondary metabolites with various types, novel structures, which can be industrialization by large-scale fermentation. This class of natural products has become an important source of antibiotics, immunological regulators and anti-tumor agents including their lead compounds and attracts great attention from researchers in natural pharmaceutical chemistry.This dissertation reports the structure and bioactivity of secondary metabolites produces by two fungi, Cladosporium sp. IFB-31p-2 from the plant Rhizophora stylosa and Aspergillus sp. YXS from the plant Ginkgo biloba. A total of thirty-one compounds from the fermentation of these two fungi were isolated by the chromatography techniques including Si gel. CC., Sephadex LH-20 and HPLC. The structures of 8 new and 21 known compounds were elucidated on the basis of spectral experiments such as HRESIMS, IR, NMR analysis. Furthermore, bioactivity effects of the compounds were evaluated using in vitro assays.Cladosporium sp. IFB-31p-2 was a fungus isolated from the healthy leaves of the plant Rhizophora stylosa. From the liquid fermentation culture of the fungus,12 compounds besides 3 new compounds and 9 known compounds. The isolated compounds were screened for their cytotoxic and acetylcholinesterase (AChE) inhibitory activity. Regretfully, no compounds were observed significant activity in these assays.Aspergillus sp. IFB-YXS was a fungus isolated from the healthy leaves of the plant Ginkgo biloba. From the solid culture of the fungus,19 compounds included 5 new compounds and 12 known compounds were isolated and elucidated. All compounds were tested the antibiotic activity and cytotoxicity. In vitro assays, compound 26 and 29 were demonstrated to be cytotoxic to HCT116, SMMC-7721, MDA-MB-231, BGC-823 cell lines with IC50 values of 2.36-7.41 μM. Compound 13,14,15,19,24,25,26,27,28 and 29 showed potent inhibitory activity in primary identification of inhibitors of anaerobic bacteria.This thesis reported the main products of these two fungi and their bioactivities. Furthermore, the recent advance concerning a natural source of macrolide was briefly reviewed.