Isolation,Identification And Antibacterial Activity Of Secondary Metabolites From Two Marine Fungi

The ocean occupies 71%of the earth’s surface area and,as a large resource treasure house,is rich in microbial species.As an important part of marine microorganisms,marine fungi have received extensive attention in recent years.Due to the special living environment of high pressure and high salt,marine fungi have different metabolic pathways compared with terrestrial microorganisms,and can produce secondary metabolites with novel structures and unique biological activities,which are important sources of drug lead compounds.In this paper,the isolation of secondary metabolites and antibacterial activity of two fungi isolated from samples from the South China Sea were evaluated.Through large-scale fermentation and cultivation,a total of 13（P1–P13）monomer compounds were isolated from Penicillium sp.JJX-1 isolated from South China Sea hermit crab.Each compound was determined by nuclear magnetic resonance（NMR）spectroscopy and high resolution mass spectrometry（HRESIMS）.The structures of each compounds are N-tert-Prenylindoles（P1）,diazinone 5（P2）,fructigenine A（P3）,fructigenine B（P4）,3-Methylviridicatin（P5）,3-O-methylviridicatol（P6）,Viridicatol（P7）,2-[（s）-hydroxy（phenyl）methyl]-3-methylquinazolin-4（3H）-one（P8）,（+）-cyclopenol（P9）,verrucosidinol（P10）,verrucosidin（P11）,norverrucosidin（P12）,anthranilic acid（P13）.Among them,compound P1 is a new natural product.The antibacterial activity showed that compound P7has moderate inhibitory activity against Staphylococcus aureus and Methicillin resistant Staphylococcus aureus（MRSA）,and its minimum inhibitory concentration（MIC）value is 8μg m L^-1.A strain of Stachybotrys sp.SCSIO 40434 was isolated from the Turbo chrysostomus collected in the South China Sea.It was fermented from its solid fermentation by using normal phase silica gel column chromatography,gel column chromatography,semi-preparative high performance liquid chromatography and other separation methods.A total of 10（S1–S10）monomer compounds were isolated and identified in the culture.The structure of each monomer was determined by NMR,HRESIMS and X-ray single crystal diffraction,which are stachybomycin A（S1）,stachybomycin B（S2）,stachybomycin C（S3）,stachybomycin D（S4）,stachybomycin E（S5）,stachybotrysin C（S6）,stachybotrylactam acetate（S7）,Mer-NF5003 B（S8）,2α-acetoxystachybotrylactam acetate（S9）,chartarutine G（S10）.Among them,compounds S1–S5 are new compounds.Compounds S5 and S7 show the same antibacterial activity as a pair of C-8 epimers,and both have moderate inhibition of Micrococcus luteus,Staphylococcus aureus and Methicillin resistant Staphylococcus aureus activity,MIC values were 8,16 and 16μg m L^-1In this paper,the secondary metabolites of two marine fungi isolated from samples collected in the South China Sea were separated.A total of 23 monomer compounds were isolated from them,including five new compounds and one new natural product.The obtained monomer compound was evaluated for antibacterial activity.This article enriches the research content of secondary metabolites of marine fungi,and provides a certain scientific basis for the rational development and utilization of marine microbial resources.