| Recently,endophyte as a new microbiology resource has played an importantrole in people discovering novel natural products.Endophytic fungi is an importantpart of the endophyte,they can produce numerous secondary metabolites with severalstructures,novel skeletons and varied and high bioactivities.They have been a veryimportant source for searching new bioactivity natural product over decades.In this thesis,three medical plants (Trewia nudiflora,Camptotheca acuminata,Annona squamosa L.) were picked as research sources.The secondary metabolites offour endophytic strains of different plants (two strains Pyrenochaeta sp.B36 andXylaria sp.A45 from Annona squamosa L.,one strain Aspergillus sp.F1 from Trewianudiflora and one strain Phomopsis sp.XZ26 from Camptotheca acuminata ) wereinvestigated.Fifty two compounds were isolated and elucidated from these fourstrains,including twenty three new compounds.Partial compounds were tested for theantimicrobe and anticancer bioactivity.There were not many research about thesemedical plants's endophytic fugi,so many compounds were isolated for the first time.Twelve compounds were isolated from the strain Aspergillus sp.F1.Theirstructures were elucidated by extensive spectroscopic data analyses,includingpolyketides,terpenoids and dibenzylbutyrolactone lignans.One of them was new polyketide,namely LT-24,named butyl 3,5-dichloro-2-hydroxy-6-(2-hydroxy-4-methoxy-6-(methoxycarbonyl)phenoxy)-4-methylbenzoate,another one was newdibenzylbutyrolactone lignan,namely LT1,named butyrolactone-V.The secondary metabolites of the strain Phomopsis sp.XZ26 for both solid andliquid fermentations were studied.Fourteen compounds were isolated.Theirstructures were elucidated by extensive spectroscopic data analyses and X-raycrystallographic analysis,including eleven (LTC,LTP,LTQ,LTJ-1,LTJ-2,LTG,LTH,26-L-2,LTL,LTM,LTR) polyketides,two (LTA,LTO) terpenoids and one (LTD)macrocyclic lactone.Among them,ten new compounds (LTC,LTD,LTG,LTH,LTJ-1,26-L-2,LTL,LTO,LTM,LTQ,LTR)were obtained.Except LTO was monoterpen,the others were all new polyketides.Compounds 26-L-2,LTG,LTL,LTM and LTR were polyketides isolated from Camptotheca acuminata fungi for thefirst time.Some of the compounds were tested for anti-microbial activities.The resultshowed that they had humble activities against Escherichia coli,Bacillus subtilis,Staphylococus aureus,Sacharomyces cereviiae and Candidia albicans.Ten polyketides were isolated and identified from the strain Pyrenochaeta sp.B36 (B36-1,LT-36-2,LT-36-4,LT-36-9,LT-36-11,LT-36-12,LT-36-15,LT-36-16,LT-36-17,LT-36-19).LT-36-2,LT-36-12,LT-36-15,LT-36-16 and LT-36-11 were newcompounds and they were isolated from Annona squamosa L.fungi for the first time.Compound B36-1 was polyketide.When tested with anticancer bioactivity,thiscompound exhibited very strong activity.At the concentration of 5μg/ml,it still has82.21% inhibition rate against the Raji cell.When tested against HEPG2 cell,at theconcentration 1.25μg/ml,it still showed inhibition rate at 49.79%.From another Annona squamosa L.'s endophytic fugus Xylaria sp.A45,thirteencompounds were obtained,including nine polyketides (LT-45-1,LT-45-2,LT-45-4,LT-45-5,LT-45-7,LT-45-8,LT-45-10,LT-45-12,LT-45-14),three new steroids(LT-45-16,LT-45-21 and LT-45-25) and one alkoid (LT-45-24).Compounds LT-45-2,LT-45-10,LT-45-16,LT-45-21 and LT-45-25 were new compounds.In conclusion,this thesis indicated that endophytic fungi,this important part ofplant system,contain novel and bioactive compounds in its secondary metabolisms.Itis an important source for searching lead compounds for drugs.
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