Study On Secondary Metabolites Of Two Endophytic Fungi From Orixa Japonica Thunb.

Orixa Japonica Thunb.is a deciduous shrub of Rutaceae,which has the effects of dispersing wind and clearing heat,intercepting malaria,and relieving pain.Alkaloids and coumarins are main chemical components of Orixa Japonica Thunb.Most of the studies on the Orixa Japonica Thunb.focus on the chemical composition and biological activity of the plant,but studies on the secondary metabolites and biological activities of the endophytic fungi of Orixa Japonica Thunb.have not been reported.Plant endophytic fungi are a kind of important microorganisms living in host plants.On the one hand,plants provide nutrition for endophytic fungi to increase the types of secondary metabolite;On the other hand,the metabolites of endophytic fungi can provide support for plants to resist adverse environment.In recent years,the development of natural drugs has become a research hotspot.Endophytic fungi have a wide variety of metabolites and rich activities,laying a material foundation for protecting plants and exploring new lead compounds.In this paper,the secondary metabolites and their biological activities of two endophytic fungi from Orixa Japonica Thunb..The following results were achieved:(1)The endophytic fungus G-(JK)-2 derived from the root of Orixa Japonica Thunb.was classified and identified as the known fungus Fusarium nematophilum through the establishment of phylogenetic tree in MEGA7.0.The Gen Bank registration number is MW376535.1.The fermentation of this strain was expanded,and a variety of separation and purification methods and identification methods were used comprehensively,and finally 13(G1-G13)known compounds were found.All compounds were isolated for the first time from the endophytic fungi of the Orixa Japonica Thunb.,and G10,G11,G13 were isolated from the endophytic fungi of Fusarium for the first time.(2)The fermentation of the endophytic fungus Diaporthe orixae sp.nov.,which originated from the stem of Orixa Japonica Thunb.,was expanded,and a variety of separation and purification methods and identification methods were used comprehensively.Finally,11(J1-J12)known compounds were found,and all of them are isolated from endophytic fungus Diaborthe orixae sp.nov.of Orixa japonica the first time.Among them,compounds 1～8 and 10～12 are isolated from Diaborthe sp.for the first time.There are 6 polyketones in these compounds and the pathway of them were deduced.(3)SPME-GC-MS was used to detect the volatile secondary metabolites of Diaporthe orixae sp.nov.fermented species with different fermentation duration.The results showed that the volatile components and relative content in the fermented products were different in each period.The relative content of 1-octene-3-ol decreased with the increase of culture time;The relative content of ethanol increased with the increase of culture time;Phenylethanol is produced after 12 days of culture,and its relative content has no obvious change with the increase of culture time at any time.It is also concluded that alcohol is the main contributor to the pleasant smell produced during fermentation,followed by ester.(4)Of the test compounds,compared with positive control group the activity of α-glycosidase showed that all compounds had week inhibitory to α-glycosidase.However,the activity of the secondary metabolite from Fusarium nematophilum in the teste were slightly stronger than that of the secondary metabolite of Diaporthe orixae sp.nov.;The results of antibacterial activity showed that the antibacterial activity of the samples tested was weak;The screening of anti-tumor activity showed that the tested compounds had the strongest inhibitory activity on MCF-7 and the worst inhibitory effect on HepG2 cells.