Isolation,Structure Analysis And Antibacterial Activity Of Secondary Metabolites From Two Marine Streptomyces

Isolation,structure analysis and antibacterial activity of secondary metabolites from marine Streptomyces were explored in this thesis.30 strains of marine actinomycetes were cultured by liquid submerge fermentation.The organic extracts were extracted by ethyl acetate from fermentation broth.Then the antibacterial activity of the crude extract against Escherichia.coli,Bacillus subtilis and Saccharomyces cerevisiae was tested by the method of filter paper diffusion.One strain of Streptomyces sp.FJNU027 with strong antibacterial activity against E.coli and B.subtilis,and one strain of Streptomyces sp.FJNU028 with strong antibacterial activity against Saccharomyces cerevisiae were selected from these strains.Streptomyces sp.FJNU027 was identified as S.griseorubens and Streptomyces sp.FJNU028 was identified as S.violascens by 16S rDNA sequencing.We then investigated the effects of crude extracts from 2 marine Streptomyces at different fermentation time on their antibacterial activity.The results showed that Streptomyces sp.FJNU027 displayed the strongest antibacterial activity of its crude extract on the 20 th day of fermentation,and Streptomyces sp.FJNU028 displayed the strongest antibacterial activity of its crude extract on the 15 th day of fermentation.5.04 g crude extract was obtained from 56 L fermentation broth of marine Streptomyces sp.FJNU027 on the 20 th day of fermentation.Seven compounds WLF04,WLF05,WLF08,WLF09,WLF10,WLF11 and WLF12 were isolated via successive chromatography over silica gel,sephadex LH-20,and reversed phase silica gel RP-18 with the guidance of bioactivity.Based on nuclear magnetic resonance(NMR),High resolution electrospray ionisation mass spectrometry(HRESI-MS)and other physicochemical data,their structures were identified as(6E,8Z)-11-(1-((1S,5R)-2,2-dimethyl-4-oxo-7,8-dioxa-6-azatricyclo[3.2.2.01,3]nonan-9-yl)ethyl)-8,10-dimethyloxacycloundeca-6,8-diene-2,4,5-trione,(1S,2Z,4Z,12R)-4,6,8,12,13-pentamethyl-13-azabicyclo[10.1.0]trideca-2,4-diene-1,7,9,10,11-pentaol,(2E,4Z)-7,9-dihydroxy-10-(1-hydroxy-2,3-dimethyl-2-azabicyclo[1.1.0]butan-4-yl)-4,6,8-trimethyl-10-oxodeca-2,4-dienoic acid,phydroxybenzoic acid,(6S,6a R)-3,6-diamino-1,8,10-trihydroxy-9,11,12,13-tetramethyl-6,6a,8,9,10,11-hexahydro-3a,6-epiminocyclohepta[e]cyclopenta[b]oxocine-2,7(3H,5H)-dione,butyl 2-(4-hydroxyphenyl)acetate and butyl 3-hydroxy-3-(4-hydroxyphenyl)propanoate.After literature retrieval,compounds WLF04,WLF05,WLF08,WLF10 and WLF12 were new.WLF04 and WLF10 showed strong antibacterial activity against Bacillus subtilis with minimum inhibitory concentrations(MIC)value of 0.5 ?g/mL and 1.0 ?g/mL,respectively.3.68 g crude extract was obtained from 71 L fermentation broth of Marine Streptomyces sp.FJNU028 on the 15 th day of fermentation.Use the same technique,thirteen compounds WLF14,WLF15,WLF16,WLF17,WLF18,WLF19,WLF20,WLF22,WLF24,WLF25,WLF26,WLF27 and WLF28 were isolated from the crude extract.WLF27 and WLF28 showed strong antibacterial activity against Saccharomyces cerevisiae.Two compounds WLF15 and WLF16 were identified as 5-(5-methyl-5-((3-methyl-8-(5-oxo-2,5-dihydrofuran-2-yl)octan-2-yl)oxy)heptyl)furan-2(5H)-one and5-(6-methyl-7-oxoo-ctyl)furan-2(5H)-one,respectively.After literature retrieval,comp ound WLF15 was new.The structures of other compounds remain to be analyzed.The research results in this paper showed that the secondary metabolites of marine actinomycetes could produce many compounds with structure diversity and antibacterial activity.They will be an important source for new antibiotics.