Studies On Antitumor Agents Of Endophytic Fungi Isolated From Juglans Mandshurica Maxim

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.Junglans mandshurica Maxim is well-known as an important pharmaceutical plant in China. The bioactive metabolites in J. mandshurica can be used to cure tumor and reduce pain. The antitumor effect of J. mandshurica has attracted great attention of scientists. However the endophytic fungi in J. mandshurica are not reported so far.Fourteen strains of endophytic fungi were isolated from the bark of J. mandshurica. The antitumor activities of the fermentation broths of these endophytic fungi were tested by MTT assay. The result showed that fermentation broths of 3 strains (FSNQ0002, FSNQ0004, FSNQ0011) had noticeable inhibition effect on the growth of HepG2 tumor cells. The phylogenetic analysis based on ITS sequences showed that they could be indentified as Thrichoderma longibrachiatum. The antitumor metabolites of FSNQ0002 which showed the highest antitumor activity were futher studied. As a result the fermentation broths of FSNQ0002 had also great growth inhibition against SPC-A-1 and SGC tumor cells, but the cytotoxicity on HL-7702 cells was relatively lower. In vivo antitumor assay showed that the metabolites of FSNQ0002 could inhibit the growth of H22 cell lines in vivo. The inhibition ratio reached 31.53%.The bioactive compound in the fermentation broths could be efficient- ly extracted with n-Butl Alcohol. The antitumor activity remained stable at 65℃for 2 h. This study provides a basic for futher purification and stability analysis the bioactive compounds.