Diversity Of The Endophytic Fungi From Vitex Negundo Var. Negundo And Vitex Negundo Var. Cannabifolia And Their Secondary Metabolites

Endophytic fungi have attracted our eyes in the whole world wide. Research results in recent years show that endophytic fungi have some regulations on their diversity and distrubition, and they can produce some metabolites same or similar to those from their host plants, and metabolites with the novel structure and specific bioactivity.In our paper, we selected Vitex negundo var. negundo and Vitex negundo var. cannabifolia in two sampling sites, to isolate and identify their fungal endophytes, and then screen bioactive activity. We also isolated and elucidated the secondary metabolites of one best bioactive strain. The main results are as follows:A total of1341endophytic fungi were isolated from Vitex negundo var. negundo and Vitex negundo var. cannabifolia in two locations. These strains were338from Vitex negundo var. negundo and362from Vitex negundo var. cannabifolia in Zhejiang sampling site;326were isolated from Vitex negundo var. negundo and315of Vitex negundo var. cannabifolia in Anhui sampling site. The composition of fungal communities differed among plant species and regions. A degree of host affinity have been observed for endophytic communities, and expressed at the level of plant genus. Cladosporium tenuissimum were only gained from Vitex negundo var. cannabifolia in the two sites, and both were predominant species in their hosts.The bioassay of the ethyl acetate extraction of the fermentation broths of the52isolations was studied. Based on the mircodilution method, bioactive endophytes were fast screened by Pyricularia oryzae P-2b model, and activities of isolations against pathogenic fungi and tumor cells were tested. Eighteen strains (34.6%) of strains from Vitex negundo var. negundo and Vitex negundo var. cannabifolia could induce morphological abnormality of Pyricularia oryza. And seven colonies (13.4%) showed excellent antifungal activities against Candida albicans, Cryptococcus neoformans, Trichophyton rubrum and Aspergillus fumigatus. And four stains (7.7%) exhibited excellent antitumor activities against HCT116、MDA-MB-435、CEM and A549tumor cell lines. Bionectria ochroleuca (T18), Acremonium sp.(T52) and Alternaria alternata (T4) displayed both excellent antifungal and antitumor effects. Interestingly, with the concentration on100μg/mL, Bionectria ochroleuca (T18) had a much higher antineoplastic effects on the four tested human cancer cell lines than the positive control. The relative high inhibition of active extracts against cancer cell line indicates that these endophytic fungi might produce potent antitumor compounds.A comparison of the compounds of the ether extracts between Vitex negundo var. negundo and its endophytic fungus Bionectria ochroleuca (T18) was investigated by gas chromatography-mass spectrometry (GC-MS). The two same compositions of the endophytic fungus and its host were n-Hexadecanoic acid and a, a-dimethyl-Benzyl alcohol.In summary, we studied the isolation, identification and bioassay of endophytic fungi, the extraction and separation of their components, and the comparative study of the bioactive strain Bionectria ochroleuca (T18) and the host Vitex negundo var. negundo.Endophytes from Vitex negundo var. negundo and Vitex negundo var. cannabifolia show the correlations between the endophytic fungi comminities and their hosts. They also exhibited excellent antifungal activity and anticancer effects, and may produce metabolites with novel structure and bioactivity. They could be a potential and rich resource for natural medicine.