Study On The Secondary Metabolite From Endophytic Fungi Of Arctium Lappa Manipulated By Chemical Epigenetic Manipulation

The endophytic fungus can produce abundant secondary metabolites and is alsothe important repository of antibiotics, immunosuppressive and cholesterol-loweringdrugs. There are a large number of endophytic fungi in medicinal plants that can bedirectly involved in the synthesis of active ingredients in medicinal plants. While theexpression of secondary metabolites in the very great degree is related to the metabolicproduct of gene cluster in fungi epigenetic state in fungi. Activating some silence genecluster of secondary metabolites without expression can greatly promote the study offungi secondary metabolites. Chemical epigenetic manipulation can restrain theactivity of the chemical epigenetic modification enzyme in specific or semi-specific,and control fungi biosynthesis. In this thesis, chemical epigeneticmanipulation(5-azacytidine) was utilized to activate the endophytic fungi from Arctiumlappa, and the insecticidal activities of the second metabolites after activation werealso tested.The study can be described as the following two parts.1、The insecticidal activity screening of secondary metabolites from Arctium lappaand eight endophytic fungi of Arctium lappa.In this part, petroleum ether, ethyl acetate and butanol were utilized to extractsecondary metabolites from Arctium lappa. Then the insecticidal activities of theextract were screened. The chemical composition of petroleum ether phase, the insecticidal activity of which is best, was analysed by GC/MS. The analysis showedthat ester, aldehyde, acids, olefinic compounds are the main components in the extract.Its relative concentration are37.83%、7.86%、2.86%and1.74%. There were23endophytic fungi isolated and purified from Arctium lappa, and named as:NY-1,NY-2,NY-3,NY-4,NY-5,NY-6,NY-7,NY-8,NY-9,NY-10,NY-11,NJ-1,NJ-2,NG-1,NG-2,NG-3,NG-4,NG-5,NG-6,NG-7,NG-8,NG-9and NG-10. Then, the insecticidalactivity of the extract from eight fungi(both mycelium and fermentation) werescreened compared with three kinds of common chemical insecticides. Thefermentation of NY-5showed the lowest LD50value. Lastly, the insecticidal activity ofthe extracts from NJ-1(mycelium and fermentation) were traced, indicating that thecompound exists in the fermentation, and especially, in the product of elution system(petroleum ether: ethyl acetate=5:1).2、Study on the secondary metabolite from endophytic fungi of Arctium lappaactivated by chemical epigenetic manipulation(5-azacytidine).In this part,5-azacytidine in different concentrations were utilized to activateeight endophytic fungi from Arctium lappa. And the insecticidal activity of the extractfrom eight fungi(mycelium and fermentation) after activated were screened. It isobvious that the insecticidal activity of fermentation of NY-1activated by10μM5-azacytidine is best. Compared with the chemical insecticides, its LD50is16timesgreater than dichlorvos. NY-1and NJ-1were identified as Asperillium niger andNeurospora tetrasperma. Lastly, the insecticidal activity of the extract fromfermentation of NY-1activated by10μM5-azacytidine was traced. indicating that thecompound was found in the product of elution system (petroleum ether: ethylacetate=20:1). The fraction compared with the chemical insecticides showed therelatively high insecticidal activity.