Study On The Antitumor Active Metabolites Of Myxococcus Marosporus STXZ54

Myxobacteria is a group of gram-negative bacteria,they are widely distributed in soils and some unfavorable environment.Scientific research shows that myxobacteria in its growth life can produce rich antibacterial,antitumor activity of secondary metabolites,such as epothilone,which has been used for clinical tumor treatment.Myxobacteria have become an outstanding source of natural products with unique structures and various bioactivity.In this study,we isolated a myxobacteria strain,Myxococcus macrosporus STXZ54 from the soil and found that its fermentation supernatant which were treated at various temperatures to observe the difference of antitumor activity of fermentation supernatant.We found that its fermentation supernatant had thermostable antitumor activity.In this paper,we studied the antitumor activity of fermentation supernatant of STXZ54,its fermentation supernatant had a broad spectrum of antitumor activity.We established a procedure and isolated four cytotoxic substances（CS） from STXZ54 fermentation supernatant.The purified CS had a broad spectrum of antitumor activity.We focused on analyzing the antitumor activity of CS3 isolated by UHPLC,Since the third fraction of CS（CS3） had the highest cytotoxicity.CS1,CS2,CS3 and CS4 were characterized by 2D-LC–MS/MS analysis,their mass fractions were 182.97 m/z,175.01 m/z,254.33 m/z and 305.09 m/z,respectively.CS3 suppressed the growth of several tumor cell lines including B16,SMMC-7721 and Hep-3B cells with IC₅₀ values in the range of 8.82 to 32.34μg/ml without obvious cytotoxicity on HUVEC cells,showing that the active component CS3 has potential clinical application value.We observed by both confocal and electron microscopy that CS3significantly changed the morphologies of tumor cells and impaird their microtubule matrixes.At low concentrations,CS3 inhibited migration and proliferation of B16 and SMMC-7721 cells.We used 10μM of Cu²⁺,Fe³⁺,Ba²⁺,Mn²⁺,Zn²⁺ and 1.5% of glucose to optimize the fermentation conditions of STXZ54 in order to improve the yield of secondary metabolites with antitumor activity.These results imply that Cu²⁺and glucose may promoted production of antitumor substances of myxobacteria and enhanced the cytotoxicity of antitumor substances on tumor cells.In this study,we established a procedure and isolated four cytotoxic substances（CS3） from STXZ54 fermentation supernatant and studied its antitumor activity.The fermentation conditions of STXZ54 were optimized by adding carbon source and trace element,which may promoted production of antibiotics or other antitumor substances of myxobacteria.The above studies enriched the gene cluster resources of antitumor substances of myxobacteria and laid an important foundation for the discovery and application of anti-tumor drug.