Studies On The Secondary Metabolites Of Two Strains Of Endophytic Fungi From Isodon Eriocalyx Var.laxiflora

Endophytic fungi can be parasitic in the living plant tissues at their whole or part of the life cycle.With their excellent ability in producing diverse secondary metabolites,endophytic fungi are considered as an important source of structurally novel and bioactive compounds.In order to explore the secondary metabolites of endophytic fungi,and to obtain novel and bioactive compounds,this paper studied the secondary metabolites of two strains of endophytic fungi isolated from Isodon eriocalyx var.laxiflora.The paper consists of two chapters.The first chapter is divided into two sections which discussed the secondary metabolites of Chaetomium sp.g1 and Phomopsis sp.shj2,respectively.The second chapter summarized the representative compounds isolated from Chaetomium from 2011 to 2018.By means of chromatographic separation technology,spectrum analysis and X-ray single crystal diffraction method,25 compounds,10 of which are new ones,were discovered from Chaetomium sp.g1,mainly including diketopiperazines,azaphilones and cytochalasans.Noteworthily,two novel skeletons,namely heteropolymeric?-butanone diketopiperazine and highly evolved nitrogenous azaphilone derivative were obtained.Moreover,10 compounds,including one new cytochalasin,were isolated from Phomopsis sp.shj2.Some selected compounds were evaluated for their cytotoxic activity.As a result,most of the diketopiperazines showed significant activity.Characteristically,the IC₅₀ value of chetomin?21?against MCF-7 was 9nM.These findings may provide a better basis for further research on the secondary metabolites of endophytic fungi from the genus Isodon.