Study On Antibacterial Constituents Of Two Endophytic Fungi From Cyclosorus Parasiticus And Picria Fel-terrae Lour

Medicinal plants and plant-derived endophytic fungi are a new resource which has latent value for exploitation,and they have become one of the major resources to discover new natural antibiotics.The chemical constituents of Picria fel-terrae Lour and secondary metabolites of endophytic fungi from Cyclosorus parasiticus were systematically investigated and some of the compounds were evaluated for their antibacterial activity in this thesis.This experiment provided new resources for developing new antibacterial drugs.The main results are included as follows:In the first chapter,the research progress of drug-resistance bacteria and antibiotic were introduced.Then,study on chemical components and pharmacological activity of medicinal plants Picria fel-terrae Lour and Cyclosorus parasiticus.Finally,the antibacterial activity and the diversity of endophytic fungi and their secondary metabolites in recent years were summarized.The second chapter described that 6 known compounds were isolated from ethyl acetate extracts of Picria fel-terrae Lour by silica gel chromatography,Sephadex LH20 chromatography and recrystallization.Their structure were identified on the basis of physicochemical property and NMR data,which are 28-O-acetylbetulin(PFL-1),Stigmasterol(PFL-2),Betulin(PFL-3),Picfeltarraenin IA(PFL-4),Picfeltarraenone I(PFL-5),Picfeltarraegenin VI(PFL-6).However,compound PFL-1 and PFL-2 were isolated from Picria fel-terrae Lour in the first time.The third chapter explained that 40 strains endophytic fungi were isolated from root,stem,leaf and rhizome of Cyclosorus parasiticus.Sensitive Staphylococcus aureus,Resistant Staphylococcus aureus,Escherichia coli and Pseudomonas aeruginosa were used as targeting microbes to test the total strains antibacterial activities by broth microdilution method.The active strains were fermented and their secondary metabolites were analyzed by TLC.Then two strains that had lots of chemical components were screened as.target strains.The forth chapter illustrated that 7 known compounds were isolated from the fermentation broth of strains of EtOAc extracts(CYC17)through silica gel chromatography,Sephadex LH20 chromatography and recrystallization.Their structure were elucidated by NMR and MS spectroscopic methods,they were 5-hydroxymethylfurfural(CYC17-1),cerevisterol(CYC17-2),1-(p-hydroxyphenyl)-2-aminoethanol(CYC17-3),4-methylbenzaldehyde(CYC17-4),pentacosanoic acid 2,3-dihydroxypropyl ester(CYC17-5),4-aminobenzaldehyde(CYC17-6),N-Ethylaniline(CYC17-7).Compound CYC17-3 was isolated from endophytic fungi firstly,compound CYC17-4,CYC17-6 and CYC17-7 were determined to be new natural products.The fifth chapter illustrated that 4 compounds were isolated from the fermentation mycelium of strains of EtOAc extracts(CYC38)by mean of silica gel chromatography and Sephadex LH20 chromatography.Based on modern spectroscopic methods,they were identied as cerevisterol(CYC38-1),cyclo(Gly-Phe)(CYC38-2),4-(2-Hydroxyethyl)phenol(CYC38-3),Cyclo(-Pro-N-MePhe-Val-Ile-Ala-)(CYC38-4).CYC38-4 was a novel compound.The sixth chapter interpreted that Sensitive Staphylococcus aureus,Resistant Staphylococcus aureus,Pseudomonas aeruginosa,Dysentery bacillus,Salmonella enterica,Escherichia coli and Salmonella typhi were used as targeting microbes to test some compounds antibacterial activities by broth microdilution method.The results indicated that compound PFL-3,PFL-4,CYC17-2,CYC17-3,CYC38-2,CYC38-3 and CYC38-4 showed inhibitory activity against Dysentery bacillus.Compound PFL-6 exhibited antibacterial activity for Escherichia coli and Salmonella enterica.Compound CYC38-4 exhibited inhibitory effect against Salmonella enterica.In addition,compound PFL-4,PFL-5,PFL-6 and CYC38-4 exhibited weak inhibitory activity against Sensitive staphylococcus aureus and Resistant Staphylococcus aureus.