Study On The Chemical Constituents And Their Allelopathy Of Four Endophytic Fungi From Eupatorium Adenophorum

This dissertation is composed of five chapters.Chapters 1-4 discuss the chemical constituents of four endophytic fungi isolated from the invasive plant Eupatorium adenophorum,the Phoma multirostrata,Trichothecium roseum,Paraphoma chrysanthemicola,and Nigrospora chinensis.In chapter 5,the allelopathy effects of the isolated secondary metabolites against the seedling and growth of Arabidopsis thaliana were discussed.The allelochemicals reported in the past ten years were reviewed in chapter 6.The chromatographic methods used in this research include normal phase silica gel column chromatography（CC）,Sephadex LH-20 gel filtration CC,medium pressure liquid chromatography（MPLC）,analytical and preparative high performance liquid chromatography（HPLC）.The structures of the isolated compounds were identified by NMR(¹H and ¹³C NMR,HSQC,¹H-¹H COSY,HMBC,and ROESY),HR-ESI-MS,ultraviolet spectroscopy,optical rotation,and other spectroscopic methods.A total of 82 compounds were isolated from the cultures of the above-mentioned endophytic fungi,among which 36 were new compounds.The new compounds were cytochalasins,sesquiterpenes,diterpenes,polyketides,andα-pyrones.Phoma multirostrata,belonging to Didymellaceae family,is a vital plant pathogen that causes plants and vegetables to rot.A total of 21 compounds were isolated from the cultures of P.multirostrata,including 13 new ones.The main structural type of the new compounds is cytochalasin.Compounds 1 and 2 are cytochalasins with a furan ring embedded in a thirteen ring.Trichothecium roseum,an endophytic fungus belonging to Hyphyoaceae family,is pathogenic to plant fruits and vegetable.A total of 22 compounds were isolated from the cultures of T.roseum,including six new compounds.The types of new compounds are trichothecenes,diterpenes,and benzene ring derivatives.The plant pathogenic fungus Paraphoma chrysanthemicola belongs to the Sphaeropsidales family.A total of 16 polyketide compounds were isolated from P.chrysanthemicola,of which 11 were new compounds.Nigrospora chinensis is a fungus of the Trichosphaeriaceae family.A total of 22 compounds were isolated from N.chinensis,including six new compounds.The new compound types areα-pyrones and drimane sesquiterpenes.Allelopathy studies showed that the ethyl acetate extract of N.chinensis and some of itsα-pyrone compounds have a moderate inhibitory effect on the germination and growth of Arabidopsis seeds.In Chapter 5,the effects of ethyl acetate extracts and some compounds from three endophytic fungi of T.roseum,P.chrysanthemicola,and N.chinensis on seed germination and seedling growth of Arabidopsis thaliana.It was found that the ethyl acetate extracts of the three endophytic fungi showed inhibitory effects on the seed germination and seedling growth of A.thaliana.The allelopathy study displayed that the ethyl acetate extract of T.roseum exhibited significant inhibitory effects while P.chrysanthemicola showed weak inhibitory effects.The trichothecenes of T.roseum significantly inhibited the germination and the growth of A.thaliana.Chapter 6 gives a comprehensive review of the allelochemicals reported in2009-2020,with 30 references cited,48 molecules discussed,this chapter describes the structures and activity of the allelochemicals.These molecules involve phenolic acids,terpenes,alkaloids and other structural types.