The Secondary Metabolites Of Endophytic Fungus R43 From Lycium Ruthenicum

Endophytes are fungi that live inter- and/or intra-cellularly inside the healthy plant tissues or organs causing asymptomatic infections for all or part of their life cycle. Recent researches have indicated that endophytic fungi have abundant species. Their secondary metabolites were ample and regared as an improtant source of active substance, which can be used as antimicrobial, antitumor, antioxidant and so on.In this thesis, the endophytic fungus which was named R43, isolated from the root of Tibetan medical plant, Lycium ruthenicum, lived in extremely condition, was picked as the research object. The strain R43 was identified as Aspergillus tubingensis by its morphological characters and internal transcribed spacer(ITS) sequence analyses.The rice was used as medium for fermenting the endophytic fungus R43. The fermentation was extracted again and again by Et OAc and Me OH, separately, and then get crude extract. Ten compounds were obtained from extract of secondary metabolites of R43 by chromatography, purified via recrystallization. Their structures of those compounds were identified by physical characteristics, chemical analysis and spectral data such as NMR and HRESI-MS. Those compounds were identified as: hexacosanoic acid(1), ergosterol(2), 6-isovaleryl-4-methoxy-pyran-2-one(3), rubrofusarin B(4), asperpyrones A(5), 2, 5-dihydroxy-benzeneacetic acid(6),campyrone A(7), succinic acid(8), daucosterol(9), D-mannitol(10). Among them, the compound 3 is a new compound, and compound 6 was reported as a metabolite of fungi for the first time.Four kinds of bacteria and four kinds of plant pathogenic fungi were tested. The result showed that compound 4 showed strong inhibitory activity against E. coli with MIC value of 1.95 μg/m L, so compound 4 can be used as a potential inhibitor against E.coli and thus it need to further develope.The antioxidant effects of all compounds were conducted. The result showed that the compound 6 has a good antioxidant activity and the antioxidant activity of compound 6 was better than vitamin C for radical-scavenging of DPPH, with IC50 value of 2.64 μg/m L.These researches enrich and perfect the study of endophytic fungi of Lycium ruthenicum. What’s more, we have provided theoretical support to futher develop and utilize endophytic fungi of Lycium ruthenicum.