Isolation, Identification Of Endophytes In Fagopyrum And The Antimicrobial And Antitumor Activity Studies

Endophytic fungi are microbes that live in the interior of plant host tissues without causing external symptoms. Endophytic microorganisms are important source for the discovery of novel bioactive secondary metabolites. Endophytes are rich source of important natural products displaying a broad spectrum of biological activities. It's very important to isolate endophytes producing bioactive secondary metabolites. Endophytes become the one new hot point of microbial medicine research.Fagopyrum dibotrys and Fagopyrum tataricum are plant of Fagopyrum of Polygonaceae, known as an important pharmaceutical plant in China. The bioactive metabolites in them have high antimicrobial, antitumor, antioxidant, hypoglycemic and hypolipidemic activity and so on. Now it is mainly studied on its plant chemical composition analysis. However, the endophytic fungi in Fagopyrum dibotrys and Fagopyrum tataricum are not reported so far.Sixty two strains of endophytic fungi were isolated from the root,stem,leaf and flower of F. dibotrys and F.tataricum. The antimicrobial and antitumor activities of the fermentation broths of these endophytic fungi were tested by K-B Disk diffusion method and MTT assay respectively. The result showed that fermentation broths of 3 strains (KQH-01,KQH-02 and JQY-1) had higher antibiotic activity to some microorganisms(Escherichia coli and Fusarium oxysporum f. sp. Cucumerinum,et al), and noticeable inhibition effect on the growth of HepG2 tumor cells. HepG2 Cell apoptosis can be induced by the ethanol exact of KQH-02 and KQH-01 with flow cytometric method, and morphologic change of cells was observed with photomicroscopy and fluorescent microscopy.The phylogenetic analysis based on ITS sequences showed that KQH-02 and JQY-1 could be identified as Chaetomium sp. and Botryosphaeria sp. respectively. The ITS sequence of KQH-01 blasted in NCBI was closed to AB255244(Xylaria sp. JP10), but the similarities was only 94%. So it is probably a new species or subspecies, which accession Number of GenBank is FJ170815.On the basis of classical modern spectroscopic analysis, the chemical constituents of secondary metabolites of KQH-02 was studied preliminarily. GC-MS analysis showed that there were mainly n-hexadecanoic acid,octadecanoic acid,oleic acid and hexadecenoic acid. Quercetin was analysed by HPLC from ethanol exact of secondary metabolites of KQH-01 and KQH-02.This study provides a basic for further research on the bioactive compounds.