Studies On The Secondary Metabolites And Their Biological Activities Produced By Six Medicinal Plant Endophytic Fungi

In this dissertation, six medicinal plants were picked as research sources.112different fungal strains were separated from these medicinal plants and screened on antifungal models,22strains showed antifungal activities were obtained. Among which, six strains were selected for further study because of their higher and broader spectrum of antifungal activities. Bioactive-guided isolation and elucidation of the metabolites of five strains obtained18compounds.15compounds were identified and among which one was a new compound, one was a new natural product, the other five compounds were isolated from the endophytic genus for the first time and still another one was obtained from the endophytic species for the first time.From the extracts of Phoma species ZJCWF006in Arisaema erubescens (Wall) Schott., six compounds were separated and two of them were elucidated as (3S)-3,6,7-trihydroxy-α-tetralone (1), cercosporamide (2), trichodermin (3), β-sitosterol (4). Monoethyl fumarate (5). Among which compound1was a new a-tetralone derivative, compound3-5were isolated from Phoma sp. for the first time. Bioactivity assays showed that compound2showed strong antifungal activities against ten tested plant pathogenic fungi. Compound2also exhibited moderate cytotoxicity against the six tumor cell lines tested. From the extracts of Phoma sp. ZJLQF335in Kalimeris indica (Linn.) Sch.-Bip., one compound was isolated and elucidated as cercosporamide (2). Optimization experiment of fermentation medium of the fungal strain resulted in yield increasing of the major metabolite2to9.32times than before.From Penicillium canescens zjqy610in Polygonatum cyrtonema Hua, three compounds were isolated and structure elucidated, including o-Acetylbenzeneamidinocarboxylic Acid (6), Griseofulvin (7) and Naphtho[1,2-b]furan-3-carboxylic acid,4-hydroxy-5-methoxy-2-methyl-(8). Among which, compound8was a new natural product from microbiology, compound6was obtained from Polygonatum sp. for the first time. Bioactivity assays showed compound7showed antifungal activities against fourteen tested plant pathogenic fungi.One compound with antifungal activities was separated from Penicillium commune TMSF169residing in Ginkgo biloba Linn. and identified as Cyclopaldic acid (9). It was isolated from P. commune for the first time. Bioactivity assays showed that compound9showed antifungal activities against twelve tested plant pathogenic fungi.From the extracts of Xylaria sp. ZJWCF255in Lycopersivon esculentum Mill. Four compounds were isolated and elucidated as cytochalasin D (10), cytochalasin C (11), cytochalasin Q (12), cytochalasin R (13). Bioactivity assays showed that compound12showed antifungal activities against fifteen tested plant pathogenic fungi.The secondary metabolites of the strain Chaetomium cupreum ZJWCF079in Macleaya cordata (Willd.) R.B was studied. Four compounds were isolated and two of them were elucidated as3,3’,6,6’-tetrahydroxy-4,4’-dimethyl-1,1’-bi(cyclohexa-3,6-diene)-2,2’,5,5’-tetraone (14) and Ergosterol (15) respectively. Compound15were isolated from Chaetomium sp. for the first time.Our study therefore underscores that endophytic fungi in medicinal plants are promising sources of natural bioactive and novel metabolites.