Study On Secondary Metabolites Of Three Strains Of Marine-derived Fungi From The South China Sea

In recent years,marine-derived fungi have played an important role in the study of natural products due to their special growth environment.With the deepening of research,scientists have discovered more and more biologically active natural products,which laid a good foundation for the development of new drugs.The aim of this study is to select biologically active strains from marine-derived fungi,and to explore the structure diversity and biological activity of their secondary metabolites.In this paper,twenty four fungal strains were isolated from mud samples collected from the South China Sea.After small-scale screening and high-throughput antibacterial activity screening,MF170022,MF170023 and MF170024 were selected as potential strains to investigate their secondary metabolites.The fermentation products of the strain were extracted by organic solvent extraction.Then the crude extract was separated and purified by means of vacuum normal phase silica gel chromatography,gel exclusion chromatography,high performance liquid chromatography.Finally,thirteen compounds were obtained.The structures of the compounds were analyzed by modern spectral techniques such as high-resolution mass spectrometry and nuclear magnetic resonance spectroscopy.The antibacterial activities of all compounds were evaluated.Seven compounds were isolated from rice fermentation products of marine fungus Talaromyces mangshanicus MF170022,including(1R,2S,6R)-6-(((E)-2-carboxyvinyl)carbamoyl)-2-((S,Z)-5-oxo-4-propylidenetetrahydrofuran-2-yl)-1-(prop-1-en-2-yl)cyclohex-3-ene-1-carboxylic acid(1),p-Hydroxybenzoic acid(2),altenusin(3),3-(propan-2-ylidene)-pyrrolidine-2,5-dione(4),(E)-3-(2,5-dioxo-3-(propan-2-ylidene)pyrrolidin-1-yl)acrylic acid(5),porric acid D(6)and nafuredin(7).Compound 1 was a new compound and compound 2-7 were known compounds.Compound 6 had anti-Staphylococcus aureus and anti-Methicillin-resistant Staphylococcus aureus activity in the evaluation of antibacterial activity,the minimal inhibitory concentration were 25 ?g/mL and 50 ?g/mL,and the minimal inhibitory concentration of other compounds was more than 100 ?g/mL.Three known compounds were isolated from the rice fermentation product of marine fungus Fusarium concentricum MF170023,including beauverin(8),eneiatin I(9)and MK1688(10).Compound 8 inhibited Methicillin-resistant S.aureus and Mycobacterium bovis in the evaluation of antimicrobial activity.Compound 9 and compound 10 inhibited S.aureus,methicillin-resistant S.aureus,Mycobacterium bovis,Candida albicans and drug-resistant Candida albicans.Three known compounds were isolated from the rice fermentation product of marine fungus Penicillium chrysogenum MF170024,including alkaloid compound meleagrin(11),diketopiperazine compound Haenamindole(12)and citreohybtidonol(13).