Metabolic Diversity And Discovery Of Natural Products Of A Marine Actinomycetes Strain SMA-1

As an important source of new natural products, marine microorganisms are a research focus. The actinomycetes strain SMA-1isolated from marine sediment in Rizhao area, Shandong province was employed in this work. One Strain Many Compounds(OSMAC) method was deployed to expand the metabolic diversity of strain SMA-1. Bioactive compounds were separated under the guidance of chemical and bioactivity assay.On the basis of OSMAC method,53media containing different carbon and nitrogen sources were utilized to cultivate strain SMA-1to obtain diverse array of secondary metabolites. The metabolic activities of53fermentation broth were determined using anti-mircobial assay. The fermentation broth with a higher anti-microbial activity was separated by TLC analysis with different solvents and indicators for improving the diversity of metabolites of strain SMA-1; two spots were found from TLC finger-printing.One active spot was picked out for further purification and structure elucidation. After organic solvent extraction, silica gel column chromatography, adsorption of macroporous resins and semi-prepared HPLC, one diketopiperazine dimer Naseseazine B was obtained.In addition, two compounds with the same molecular weight as Naseseazine B from No.40fermentation broth were identified on the basis of triple quadrupole MS analysis. Chemical structure of three diketopiperazine dimmers with isomeric characterstics iso-Naseseazine B, Naseseazine B and aspergilazine A were elucidated on the basis of spectrum analysis of MS and NMR.