Secondary Metabolites Of Two Streptomyces Sp. And Their Biological Activity

The resistance of multiple chemotherapeutic drugs and their toxicity effects has increased demand for novel antitumor drugs.Therefore,novel drugs is still the priority goal for cancer and serious diseases therapy.Currently,there are many antitumor drugs are derived from microorganism metabolites,and Streptomyces is an important source of microbial drugs.In this thesis,two species of Streptomyces were studied by chemical and bioinformatics methods.The Streptomyces sp.OC1610.4 was isolated from an intertidal sediments.In the whole genome sequence,analyzed by antiSMASH 5.0 software,there are 19 biosynthetic gene clusters were presented and the secondary metabolites,including angucycline glycosides,desferrioxamine and geosmin could be confirmed.After large scale fermentation,four angucycline glycosides including three new compounds landomycin N,galtamycin C and vineomycin D,and one known homologue saquayamycin B,along with two alkaloids 1-acetyl-β-carboline and indole-3-acetic acid,were isolated from the fermentation broth.Their structures were established by IR,HR-ESI-MS,1D and 2D NMR techniques.The cytotoxic activity of landomycin N,galtamycin C,vineomycin D,saquayamycin B was assayed by MTT and CCK-8 methods.Saquayamycin B displayed potent cytotoxic activity against human hepatoma cells HepG-2,SMMC-7721 and plc-prf-5,with IC50 values 0.135,0.033 and 0.244 μM respectively,superior to doxorubicin.Saquayamycin B also induced apoptosis in SMMC-7721 cells as detected by its morphological characteristics in 4’,6-diamidino-2-phenylindole(DAPI)staining experiment.The apoptotic ratio of SMMC-7721 cells was dependent on the concentrations of saquayamycin B.The Streptomyces sp.N1508.10 was isolated from the mud dauber wasp Sceliphron madraspatanum.In the whole genome sequence,analyzed by antiSMASH 5.0 software,indicated the presence of 51 biosynthetic gene clusters and the predicted secondary metabolites,include pyrones,ansamycins and lobophorins.The large-scale fermentation and chromatography isolation resulted in the identification of fourteen metabolites containing five germicidins germicidin A,germicidin B,germicidin C,isogermicidin A and isogermicidin B,seven aromatic compounds,and one ansamycin divergolide Ⅰ,along with one macrolide lobophorin A.Their structures were established by HR-ESI-MS,1D and 2D NMR techniques.Hexokinase Ⅱ inhibitory activity of the isolated compounds were assayed,4-(2-aminoethyl)phenyl acetate,germicidin B,2-phenylacetic acid,isogermicidin A and germicidin C showed inhibitory activity against hexokinase Ⅱ,with IC50 values 5.11,7.11,7.15,8.45 and 8.78 μM,respectively.