Secondary Metabolites Of Endophytic Fungus Eef-B14 Isolated From Eucalyptus Exserta F. Muell And Their Biological Activities

Plant endophytic fungi are rich in nature environment and most of them can produce abundant secondary metabolites with excellent biological activities,which is considered as natural product treasures for the human.In this research endophytic fungus Eef-B14 isolated from Eucalyptus exserta F.Muell was selected,and the secondary metabolites of endophytic fungus Eef-B14 were obtained through a large-scale solid-substrate fermentation process with rices and extracted by organic solvent.Then the pure compounds of this fungus were isolated and identified.All the compounds were evaluated with antibacterial and antioxidant activities.The main results were as follows:1.Thin layer chromatography assay,reduced pressure chromatography assay,sephadex LH-20 assay and semi-preparative high-performance liquid chromatography were used in the whole process.3 compounds were isolated and purified from the petroleum ether and ethyl acetate extract of endophytic fungus Eef-B14.These compounds were identified by 1D NMR,2D NMR,HR-ESI-MS and compared with the reference.All in all,3 compounds were identified as 5-Deoxybostrycoidin?W16Y?,Scorpinone?W24?and 4-Methyl-5,6-dihydro-2-pyranone?WE?.2.The antibacterial activities of the compounds against seven test bacteria were determined by perforated plate-MTT colorimetry.The results showed that compound Scorpinone?W24?had a certain inhibitory activity against a variety of test bacteria.The IC₅₀ values of Scorpinone?W24?on Escherichia coli and Xanthomonas vesicatoria were 12.32±0.74?g/mL and 9.51±0.98?g/mL,respectively.There was no difference in antibacterial activity between gram positive and negative bacteria.And other compounds showed no antibacterial activity.3.The antioxidant activities of the compounds obtained were calculated by DPPH clearance rate,and none of them showed antioxidant activities.The DPPH clearance rates of 5-Deoxybostrycoidin?W16Y?and Scorpinone?W24?were only about 5%at a concentration of 1 mg/mL.This study indicated the structure and type of the secondary metabolites in the endophytic fungi Eef-B14,which providing a valuable theoretical basis for the comprehensive exploitation and utilization of endophytic fungi and their secondary metabolites.