Research On Secondary Metabolites From Soft Coral-derivied Symbiotic Fungi NG-15-3 Of South China Sea By OSMAC Strategy

Microbial secondary metabolites had a wide range of biological activities because of their structural diversity and have been proved to be a major source for drug lead compounds.However,the traditional method of single culture restricts the metabolic pathways of microorganisms,therefore many secondary metabolites could not be formed.So,the study of using the OSMAC(One strain many compounds)strategy on a coral-derivied symbiotic fungi NG-15-3 was performed to activate the silent biosynthetic pathway and produce more novel structure of secondary metabolites.In this research,by using the OSMAC strategy with different fermentation media to culture the fungi and as a result,we found the TLC and HPLC fingerprients of this strain,which could use to instruct the further study of secondary metabolites of this fungi.In the study of secondary metabolites of NG-15-3 with D fermentation media,26 compounds were isolated by all kinds of colum chromatography,such as silica gel,sephadex LH-20 and purified by HPLC.And 19 structures were identified on the basis of spectral data(NMR,MS),physical constant comparison and chemical methods:tetrahydroauroglaucin(3-1)、flavoglaucin(3-2)、isodihydroauroglaucin(3-3)、2-(1’,5’-heptadienyl)-3,6-dihydroxy-5-(3"-methyl-2"-butenyl)benzaldehyde(3-4)、asperentin-8-O-methyl ether(3-5)、monomethyl cladosporin(3-6)、asperentin/cladosporin(3-7)、5’-hydroxyasperentin(3-8)、4’-hydroxyasperentin(3-9)、cladosporin 8-O-α-ribofuranoside(3-10#)、2S-hydroxydiplopterol(3-11)、emodin(3-12)、1-O-methyl emodin(3-13)、physcion(3-14)、xanthorin(3-15)、asperflavin(3-16)、neoechinulinA(3-17)、preechinulin(3-18)、variecolorins L(3-19)and subergorrgic acid(3-20)。Compound 3-10 was a new dihydroisocoumarin natural product,which showed varied biological activity.And 3-20 was the first time isolated from microorganism.Compared to the secondary metabolites of NG-15-3 with GPY fermentation media,two media can produce dihydroisocoumarins,anthraquinones and diketopiperazines.However,GPY media also produce cyclic dipeptides and imidazole derivaties,while the other one comes out benzaldehydes and triterpenoids.As a result,different environments could produce secondary metabolites,and the OSMAC strategy was comfirmed.But the biosynthesis pathway and its pharmacological activity of the secondary metabolites were further to research.