| Microbial natural products are the main source of medical antibiotics and agricultural antibiotics in the market,and have made great contributions to human health and modern agriculture.However,with the extensive use of antibiotics,bacterial drug resistance is gradually increasing,which poses a serious threat to human health and the environment,and has become a global security problem.Therefore,it is urgent to develop new antibiotics or new antibacterial mechanisms to combat bacterial drug resistance.Actinomycetes mainly inhabit the soil,and despite more than 60 years of soil actinomycetes screenings,only a small number of actinomycete taxa have been identified.Therefore,it is of great significance to obtain active actinomycetes producing new antibiotics from soil.In this study,the actinomycetes were isolated and purified from the sediment of Taihu Lake,and the obtained actinomycetes were screened for the activities of anti pathogenic fungi,anti pathogenic bacteria and anti-tumor cells;Then,the strains with superior activity were preliminarily classified and identified,and their secondary metabolites were isolated and extracted through a large number of fermentation.The main results are as following:（1）A total of 89 strains of actinomycetes were isolated from two sediment of Taihu Lake,and the anti-pathogenic fungi,anti-bacteria and anti-tumor cell activities were screened,and two active strains,Streptomyces sp.NEAU-TD2-4 and Streptomyces sp.NEAU-TD1-19.（2）The strain NEAU-TD2-4 was screened with three fermentation medias,GYM,PTM and cottonseed cake meal,and finally determined to use GYM fermentation media for 30L fermentation.After pretreatment,the fermentation broth is separated and purified by normal phase silica gel column chromatography,LH-20 gel column chromatography,preparative HPLC,and semi-preparative HPLC.Then,modern analytical techniques such as NMR,HRESIMS,IR,and UV were used to determine the structure of compounds.A total of 6 compounds were isolated from this strain,which was identified as khusinodiol（1）,4,8-dihydroxy-4-methyl-1-oxo-1,2,3,4-tetrahydronaphthalene-3-carboxylic acid（2）,1H-indole-3-carboxylic acid（3）,5-（2-Methylphenyl）-4-pentenoic acid（4）,streptoprenylindole A（5）,N-Acetyltyramine（6）,of which Compound 2 is a new compound.（3）Carry out the primary screening of the above three fermentation medias for strain NEAU-TD1-19,and finally determine to use cottonseed cake meal fermentation media for 30L fermentation.The methods for separation,extraction and compound structure determination are the same as above.A total of 10 compounds were isolated from this strain,which was identified as（S）-2-（3-acetylamino-2-methyl）propyl-3-butyl-2-cyclopenten-1-one（7）,（S）-2-（3-acetylamino-2-ethyl）-propyl-3-butyl-2-cyclopenten-1-one（8）,3-（sec-butyl）Hexahydropyrrolo[1,2-c]pyrimidine-1,4-dione（9）,cyclo-Leu-Pro diketopiperazine（10）,Rubiginone B2（11）,Fujianmycin A（12）,trans-Ferulic acid（13）,8-O-4-dehydrotriferulic acid（14）,gombapyrones A（15）,gompayrones B（16）.Compound 7 and compound 8 are new compounds.The absolute configurations of compound7 and compound 8 were established by comparing the theoretical rotation value with the experimental rotation value.（4）Isolated compounds 1-16 were tested for activity,and the results showed that compound 4had inhibitory activity against the six pathogenic fungi tested,and the inhibition rate was 24%-35%.Compound 12 has good inhibitory activity against Staphalococcus aureus,Bacillus subtilis,Ralstonia solanacearum and Micrococcus luteus,and the inhibition zone is about 20mm.Compound 5 and compound 12 had potent antitumor activity.The IC50values of compound 5against 4T1 mouse breast cancer cell lines and human tumor cell lines HCT-116 were 4.8μg/m Land 4.3μg/m L,respectively,and the IC50values of compound 12 were 5.3μg/m Land 5.6μg/m L. |
