Studies On Secondary Metabolites From Six Streptomvces Strains And Their Biological Activities

Actinomycetes is a kind of one-celled organism between bacteria and fungi.It is wildly distributed in nature,especially in the alkalescent soil with rich organic matter.The greatest economic value of actionmycetes is that it can produce a variety of antibiotics.More than 60% of the antibiotics which have been found in microorganism are produced by actionmycetes,and 90% of them are from Streptomyces for actionmycetes.Therefore,Streptomyces is one of the most important sources for the lead compounds in natural products and has important research value.This dissertation mainly focuses on the bioactive secondary metabolites from plant rhizosphere soil-derived Streptomyces.Six Streptomyces strains were selected as the object of this study by chemical and biological activity screening results results.They were from Polyalthia cerasoides rhizosphere soil-derived Streptomyces sp.KIB-1414,Ailao Mountain soil derived Streptomyces sp.KIB-D2,Tengchong soil derived Streptomyces sp.KIB-3101,Magnolia liliflora Desr.rhizosphere soil-derived Streptomyces sp.KIB-1782,Cassia tora Linn.rhizosphere soil-derived Streptomyces sp.KIB-1757,Caluo soil derived Streptomyces sp.KIB-1170,respectively.The purpose of this research topic is to discover the new natural products with good biological activity from Streptomyces.This study may set up the stage for the new product development in medicine,food,energy and environmental protection.The selected strains were cultured by liquid fermentation technology to obtain crude extracts.Then the secondary metabolites of six Streptomyces strains were isolated and purified by various chromatographic techniques(reversed silica gel column chromatography,thin layer chromatography,Sephadex LH-20 column chromatograph,MCI,high performance liquid chromatograph),and 40 compounds were obtained.Structure elucidation of 40 compounds was performed by means of various spectral analysis techniques,including nuclear magnetic resonance spectroscopy(NMR),mass spectrum(MS),infrared spectroscopy(IR),ultraviolet spectrum(UV)combined with the spectroscopic data reported in the literatures,and 15 of them elucidated as new compounds.The structure types of isolated compounds include fasamycins,formicamycins,anthraquinones,chromones and meroterpenoids.These isolates from Streptomyces sp.KIB-1414,Streptomyces sp.KIB-D2 and Streptomyces sp.KIB-1757 were tested for antimicrobial activity.Compounds 1-17,37 and 38 showed good antimicrobial activity.