Antibacterial Metabolites Of Two Endophytic Fungi

The novel structure and active secondary metabolites produced by symbionts play an important role in environmental adaptability and resistance to natural enemies of their host.This dissertation presents the structure elucidation and bioactivity evaluation of secondary metabolites produced by two fungus isolated from ginkgo biloba and Tenodera aridifolia Stoll.The crude extracts derived from the cultures of the two strains were repeatedly fractionated by a combination of chromatographies over normal-and reverse-phase ODS silica gel,gel filtration over Sephadex LH-20 and HPLC to afford a total of 30 compounds,including 13 new compounds.These compounds were elucidated by spectroscopic analyses including MS,UV,IR,CD,1D and 2D NMR.Furthermore,some of the natural products were found to have antifungal activities.On the basis of our previous research,we added 3-Indolylcarbinol to active the sliente genes of Daldinia eschscholzii IFB-TL01 to generate novel unnatural products.In order to clarify the biosynthetic pathways of these compounds,we added macroporous resin in the medium during the fermentation.Finally,we obtained 21 compounds,including 13 new compounds.Compounds 4 showed moderate cytotoxicity to human tumor cell lines such as SW480、HL-60、HepG-2、A375、MCF-7,and significant inhibitory on the growth of bacillus subtitles with a minimum inhibitory concentration(MIC)value of 2.3 μM,which is more potent than streptomycin(MIC 0.62 μM),an antimicrobial drug co-assayed herein as a positive reference.Aspergillus sp.IFB-YXS,an endophytic fungus,was isolated from of ginkgo biloba.The liquid fermentation,followed extraction and fractionation,gaving 9 terphenyl derivatives.All the compounds were evaluated for cytotoxic activity,compound 24 and 25 have inhibition on the growth of the phytopathogenic bacterium Phytophthora capsici Leonian and Fusarium moniliforme Sheldand.compound 30 shows significant inhibitory on the growth of the phytopathogenic bacterium Clavibacter michiganense subsp.Sepedonicus with MIC value of 0.31 μg/mL,which is more potent than streptomycin(MIC 0.62 μg/mL),an antimicrobial drug co-assayed herein as a positive reference.Furthermore,some representative examples about natural bioactive products from endophytic fungus were reviewed briefly.