Study On The Isolation And Secondary Metabolites Of Endopytic Fungi From Sophora Tonkinensis

Endoptytic fungi can produce various bioactive secondary metabolites with novel structures.The researches of secondary metabolites of endophytic fungi have become a research hotspot in natural products chemistry.Sophora tonkinensis is a Chinese traditional medicinal plant used for the treatment of cancer,dermatitis,gastrointestinal hemorrhage,throat swelling,and acute pharyngolaryngeal infections.The main purpose of this dissertation was to investigate antimicrobial compounds from the endophytes isolated from S.tonkinensis.The research was performed on the isolation and investigation on secondary metabolites of endophytic fungi from S.tonkinensis.The main contents of this dissertation are summaried as follows.1.Survey of antibacterial metabolites of endophytic fungi.2.Isolation and identification of endophytic fungi from Sophora tonkinensis.A total of 126 endophytic fungi were isolated from Sophora tonkinensis collected from Jingxi City.45 strains were isolated from the leaves,34 strains were isolated from the stems,and 47 strains were isolated from the roots,accounted for 35.7%,27.0%and 37.3% respectively for the total strains.Among them,24 strans belong to Fusarium sp.,22 strains belong to Xylaria sp.,10 strains belong to Colletotrichum sp.,and 6 strains belong to Penicillium sp..3.Study on secondary metabolites of endophytic fungus GDGJ-91(Penicillium sp.).Two new compounds,(–)-3-carboxypropyl-7-hydroxyphthalide(91-1)and andrastin G(91-4),along with eleven known compounds 7-hydroxyphthalide(91-2),(3S)-4,5-dihydroxy-3-butylphthalide(91-3),andrastin A(91-5),citreohybridonol(91-6),dankasterone A(91-7),orsellinic acid(91-8),2,4-dihydroxy-3,6-dimethylbenzoic acid(91-9),2,5-dihydroxylbenzoic acid(91-10),3-(1’-carboxyvinyloxy)-benzoic acid(91-11),asteltoxin(91-12)and 3,6,8-trihydroxy-4-methoxy-1-methylxanthone(91-13),were obtained from the metabolites of GDGJ-91.The structures of compounds were confirmed by NMR spectroscopy.Compound 91-3 was isolated from microorganism for the first time.4.Study on the secondary metabolites of endophytic fungus GDGJ-37(Penicillium sp.).Seven known compounds,ergosterol(37-1),sclerotiorin(37-2),2,4-dihyroxy-6-(5,7-dimethyl-2-oxo-trans-3-trans-5-nonadienyl)-3-methylbenzaldehyde(37-3),(22E,24S)-5α,8α-peroxideergosta-6,22-diene-3β-ol(37-4)、ergosta-4,6,8,22-tetraen-3-one(37-5),β-sitosterol(37-6)and pencolide(37-7),were seperated from GDGJ-37.Their structures were evaluated by NMR spectroscopy.Compound 37-5was isolated from Penicillium sp.for the first tiem.5.Study on the secondary metabolites of endophytic fungus GDG-102(Xylaria sp.).Ten compounds,ergosterol(102-1),(2S,5R)-2-ethyl-5-methylhexanedioic acid(102-2),xylariphilone(102-3),2-methoxy-6-methyl-1,4-benzoquinone(102-4),2-anhydromevalonic acid(102-5),6-heptanoyl-4-methoxy-2H-pyran-2-one(102-6),5-carboxylmellein(102-7),xylarphthalide A(102-8),1β,10α,13-trihydroxyeremophil-7(11)-en-12,8-olide(102-9)and cytochalasin K(102-10),were isolated from the metabolites of GDG-102.The structures of compounds were confirmed by NMR spectroscopy.Compounds 102-2,102-3,102-4,and 102-5 were isolated from Xylaria sp.for the first time.6.Antibacterial activities assay.Antibacteial activity of compounds 91-1–91-3、91-5–91-10,91-12,91-13 102-2–102-5 and 37-2–37-7 against six bacteria were evaluated.102-4 showed prominent inhibitory activities against Bacillus subtilis and Bacillus megaterium with MIC values of 1.56 μg/m L and 3.13 μg/m L.The inhibitory activities of 37-2 against Shigella dysenteriae,Bacillus megaterium and Enterobacter aerogenes with MIC values 3.13 μg/m L,1.56μg/m L and 12.5 μg/m L,respectively.