Secondary Metabolites Of Soil-derived Aspergillus Niger:Structures And Bioactivites

ObjectiveIsolating and screening of fungus with luxuriant secondary metabolite from the soil.Classification of strains by morphological,physiological,biochemical and molecular biol-ogical characterization.Optimization of soild fermentation conditions,study on the structu-re and biological activity of the secondary metabolites Lay the foundation for the use of biological and new drugs development.Method4 strains were isolated from soil by multiple dilution and plate streak.4strains of fungus were isolated from the soil carried out by using rice medium.Thin Layer Chromatography preliminary analysis of solid culture crude extract comparison of the composition and content of each strain,study on the solid fermentation and the components of the secondary metabolites of Aspergillus niger.Silica gel column chromat-ography of solid culture extract reuse Sephadex gel column chromatography separation and purification.The structures of the target compounds were identified by NMR.Determination of biological activity of monomeric compounds of known structure,the antibacterial activity of the compounds was determined by filter paper method,activity of compounds was determined by the inhibition or promotion of tyrosinase,the optimum reaction system was determined in vitro.ResultsWith the method of Silica gel column chromatography with Glucan gel column chromatography,we successfully isolate 15 kinds of monomer compounds with X_5-1-X_5-15from Aspergillus niger,identified as naphthopyran ketones and steroidal compounds.The biological activity test showed no obvious effect on the antibacterial activity of filter paper method,but the inhibitory effect on the tyrosinase activity was obvious.Conclusion15 kinds of compounds were isolated from Aspergillus niger,and the results showed that there were 14 kinds of compounds in the determination of tyrosinase activity,of which there are 6 kinds of compounds have inhibitory effect on tyrosinase,the 8 kinds of compounds have no obvious effect.?1?Monomeric compound of X_5-1,X_5-2,X_5-5,X_5-7,X_5-8,X_5-11,X_5-13-13 and X_5-15-15 showed no significant inhibition or promotion related to tyrosinase.?2?Monomeric compound of X_5-3,X_5-6,X_5-10-10 and X_5-14-14 had significant inhibitory effect on tyrosinase,And X_5-6,X_5-10-10 and X_5-14 inhibition of tyrosinase enhanced with increasing concentration,The inhibitory effect of X_5-3 on tyrosinase was increased with the enhance of concentration and then decreased,and the specific mechanism needs further study.?3?The inhibitory effects of X_5-3,X_5-6,X_5-10-10 and X_5-14 on tyrosinase were compared with that of L-ascorbic acid?Vc?,X_5-10-10 and X_5-14-14 inhibitory effect on tyrosinase was better,but the inhibitory effect of X_5-6-6 on tyrosinase was worse.?4?The inhibitory effect of X_5-4-4 and X_5-9-9 on tyrosinase was lower than that of other monomers,especially X_5-9.?5?The optimum reaction system for the interaction between the monomer compound and tyrosinase is:the temperature is at 25?and pH=6.5,which is consistent with the specification.?6?Display of naphthopyran ketones on Staphylococcus aureus and Escherichia coli,yeast filter experiment method:in addition to the corresponding antibiotic bacteriostatic ring,other compounds showed no significant effects.