Study On The Secondary Metabolites Of Streptomyces Sp.CJ0806 And Its Anti-breast Cancer Activity

Insects are the largest and most diverse animals on the earth,so there are many kinds of microorganisms that are symbiotic with insects.Affected by the complexity and variability of symbiotic insects,the secondary metabolites produced by insect symbiotic bacteria have novel structures and good activities.Some products have obvious anti-tumor,anti-bacterial,anti-malarial,and other activities.They are prolific active secondary metabolites and have great research potential in drug development.It is of great significance to study the secondary metabolites of insect symbiotic bacteria in order to explore potential lead compounds.In this paper,100 strains of symbiotic bacteria from Camponotus japonicus were isolated by the plate dilution method.Most of the strains were identifi ed as Streptomyces by 16S rDNA sequence analysis.The secondary metabolites of all strains were further screened for preliminary pharmacological activity.The results showed that the secondary metabolites of strain CJ0806 had good activity against breast cancer cells,so Streptomyces sp.CJ0806 was selected as the experimental strain.The genome of Streptomyces sp.CJ0806 was sequenced and analyzed using antiSMASH software.A total of 39 secondary metabolite biosynthetic gene clusters were found,including class I polyketides,class Ⅱ polyketides,and sesquiterpenes.A large number of Streptomyces sp.CJ0806 were fermented.The secondary metabolites of strain CJ0806 were isolated by conventional column chromatography(CC),C18 reverse silica gel column chromatography(ODS),gel column chromatography(Sephadex LH-20),high performance liquid chromatography(RP-HPLC)and other methods,combined with biological activity tracking methods.Seven compounds were isolated and identified as class II polyketides by nuclear magnetic resonance,mass spectrometry,and other spectroscopic methods.The secondary metabolites of strain CJ0806 were measured by LC-MS/MS,and the mass spectrometry data were processed by MZmine 2 software,and uploaded to the GNPS network platform to construct a molecular network,which was matched with the existing compounds in the molecular network library.The results showed that the strain had other anthraquinone compounds,and had the potential to synthesize new compounds,and there was a need for continued separation.Finally,the antitumor activity of the compounds was screened by MTT assay.The results showed that aclacinomycin A had strong cytotoxic activity against human breast cancer cells MCF-7,MDA-MB-231,and MDA-MB-453,and its IC50 was 0.23-0.37 μM.In order to further investigate the inhibitory effect of aclacinomycin A on the invasion of human breast cancer cells,scratch tests and Transwell tests were carried out.The results showed that aclacinomycin A could inhibit the migration and invasion of human breast cancer cells,and had the potential for further research.