The Studies On Isolation, Identification And Its Secondary Metabolites Bioactivity Of Endophytic Fungi From A.Monadelphus

Endophytic fungi are a special and important group of microorganisms with taxonomic diversity as well as producing the same or similar compounds, which show high potential as sources of antimicrobial, antioxidant,anticancer and insecticidal compounds et al. Astragalus Linn, possess a variety of pharmacological activity and widely used in clinical.This thesis research in bioactivity and bioactives of secondary metabolites of endophytic fungi which isolated from medicinal plant A.monadelphus. Studies include isolate of endophytic fungi, antimicrobial activity test, antioxidant activity test. The results are concluded as follows:(1) Thirteen strains were isolated from fresh A.monadelphus,7strains were identified by18SrDNA and belonged to Ascomycotina and Deuteromycotina, classified into6genus:Aspergillus sp.(2)%Penicillium sp.(1)、 Acremonium sp.(2)、 Rhinocladiella sp.(1)、Alternaria sp.(1) and Fusarium sp.(1).(2)Fermentation of each strain was extracted by ethyl acetate and n-botanol, the biomass was extrated by ethanol. These extracts were tested by two bioactive screening programs including anti-microbial activity and antioxidant activity. The extracts were evaluated for their antimicrobial activities agains six tested baceterial. The results indicated that14samples (35.89%) showed antibaceterial activity against at least one test bacterium,11among them were extracted by ethyl acetate. The sample which extracted by ethyl acetate of H601and H803showed strong antibaceterial activity and the MIC against test bacteria was0.25mg/mL.(3)The extracts were evaluated for their antioxidant activities by potassium ferricyanide reduction method、OH scavenging activity test and DPPH-scavenging activity test. The results are concluded as follows:All of the samples have different levels of deoxidizing ability. Under the same concentration, the sample of H401showed higher deoxidizing activity than other samples.OH scavenging activities of the extracts showed greater differences.4samples displayed pronounced scavenging, and their scavenging rate are over70%. Especially, the extracts from biomass of H802showed stronger-OH scavenging than Vc.DPPH-scavenging activities of all samples are over50%, and the samples which extracted by ethyl acetate possess higher scavenging activity than others. The scavenging rate of four samples are over80%, H401showed stronger DPPH-scavenging than Vc.(4)Using repeated column chromatography on silica gel, preparative thin layer chromatography (PTLC) and recrystallization,1compound was separated from strain H401, which were identified to β-sitosterol. Further study demonstrates the compound have no antioxidant activitiy.