| Actinomycetes secondary metabolites are important sources of drug lead compounds.Actinomycetes are one of the important biological groups in the soil.Due to the easy breeding of the strains,the fermentation time is short,and it is easy to carry out metabolic control.It can be industrialized by large-scale fermentation.Therefore,they have traditionally been the most prolific group in antibiotic production.The soil is the main habitat of actinomycetes.Therefore,studying the secondary metabolites of soil actinomycetes is still an important direction for actinomycetes research.In this study,soils from different habitats were used as the separation source of actinomycetes,the isolated actinomycetes were fermented,the fermentation products were extracted and separated,and their structure was identified.The absolute configuration of secondary metabolites was studied.(1)Two separate culture media(HV,GS)were used to screened the soil collected from the 100-year-old red pine tree in Yichun City,the root of the Yellow River in Linyi City,and the deep mountain environment in Yangshuo,and 40 actinomycetes were isolated finally.(2)Growth inhibition experiment of Rhizoctonia solani,Sclerotinia sclerotiorum,Canidia albicans,Staphylococcus epidermidis were performed with 40 actinomycetes.The results showed that 37.5 percent of actinomycetes showed the ability to suppress indicator bacteria and 32.2 percent of actinomycetes showed the ability to suppress at least one kind of pathogenic fungi.The 17 strains with good effect on inhibiting fungi or bacteria were all fermented by the medium GYM and H9.We tested the antimicrobial activities and the cytotoxicity against the growth of human colon cancer cell line HCT-116 of the crude extracts from fermentation broth.The results showed that 2 strains showed good antifungi or antibacteria effect.At the moment,the inhibition rate of 8 strains were more than 50 percent when the sample concentration was 100 ?g/m L and 3 strains showed that the inhibition rate were still greater than 50 percent when the sample concentration was 20 ?g/m L.(3)Fermenting two strains of Streptomyces sp.HS-NF-780 and Streptomyces sp.HS-NF-1542,and the fermentation broth is pretreated by suction filtration,centrifugation,resin adsorption and so on.With the use of silica gel,LH-20 and HPLC,the isolation of the fermentation broth was taken on.9 compounds were finally obtained,and their structures were elucidated on the basis of spectroscopic analysis,including 1D and 2D NMR,as well as UV,IR,HRESIMS,1H-1H COSY,HMQC,and HMBC.Seven compounds 1-7 were extracted from the strain Streptomyces sp.HS-NF-780,and compounds 1-6 were all glutarimide compounds,among them compounds 1,3,4 were new compounds called hydroxyiso-9-methylstreptimidone,9-methylstreptimidone 2-?-D-glucopyranoside,(2E,6E,8E)-3'-(1'-amino-1'-oxoethyl)-11,12-dimethyl-4-oxotrideca-2,6,8-trienoic acid;Two known compounds 8-9 were extracted from the strain Streptomyces sp.HS-NF-1542.(4)The absolute configuration of compounds 1,3 was studied.By modified Mosher's method,the absolute configurations of compound 1 at C-2 was assigned as R,and at C-9 was epimer mixture.Chiral HPLC analysis of compound 1 with a CElluose-C column,further indicated that compound 1 was epimeric,mixture in a ratio of approximately 3:2.Acid hydrolysis of compound 3 to abtain aglycone moiety and sugar residue.The retention time of the aglycone moiety of compound 3 was in good agreement with compound 2,which suggested that the aglycone moiety of compound 3 was 9-methylstreptimidone.The sugar residue and standard sugar were derived and analyzed,they have same retention time.Thus,the absolute configuration of glucose was D-Glucose.(5)Finally,the antimicrobial activity of new compounds 1,3,4 were tested.Among them,the new compounds 1,3,4 had moderate antitumor activity against human leukemia cell K562,breast cancer cell MCF-7 and colon cancer cell HCT-116.The IC50 values of K562 cells were 36.47,28.37,10.50 ?g/m L,respectively.The IC50 values of MCF-7 cells were 34.68,28.79,5.43 ?g/m L,respectively.The IC50 values of HCT-116 cells were 36.76,34.83,20.49 ?g/m L,respectively.At the moment,compound 1 exhibited inhibitory activity against Sclerotinia sclerotiorum.And compound 4 exhibited inhibitory activity against Canidia albicans and Sclerotinia sclerotiorum. |
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