Study On The Chemical Composition And Antibacterial Activity Of Secondary Metabolites Of Aspergillus Fumigatu SZW01

Marine fungi have many advantages such as wide distribution,variety,short cycle,fast reproduction and rapid metabolism,forming a huge treasure of biological resources.The secondary metabolites have a novel structure and a wide variety.Therefore,marine fungi have become an important resource for research and development of marine drugs.In recent years,Aspergillus fumigatus has gradually become a hot topic in microbial pharmaceutical research,and its secondary metabolites have received special attention due to their special chemical structure and good biological activity.Most of their chemical structures are alkaloids,polyketones,terpenes and other compounds,which have good biological activities such as anti-inflammatory,antibacterial and anti-tumor.It provides a broader space for the research and development of pharmaceutical lead compounds.Using a method combining microbial morphology and molecular biology ITS sequence Gene Bank alignment,the strain SZW01 was identified as Aspergillus fumigatu.Rice medium was used for large-scale fermentation,and then dichloromethane and n-butanol were used for extraction.Finally,thin layer chromatography was used to determine the dichloromethane layer extract as the experimental object to study its chemical composition.A variety of chromatography methods:reverse ODS column chromatography,preparative thin layer chromatography,silica gel column chromatography,and dextran gel column chromatography were used to separate and purify the extracted crude extract to obtain 10 compounds.Combined with various methods such as¹H NMR and¹³C NMR of modern spectroscopy to analyze the compounds’spectra,the structures of 10 compounds were identified as follows:fumigaclavine C（1）,cyclo（L-Tyr-L-Pro）（2）,cyclo（L-Phe-L-Phe）（3）,dibutylphthalate（4）,1,2-seco-trypacidin（5）,Emodin（6）,chrysophanol（7）,3-methyl-6,8-dihydroxyisocoumarin（8）,4-hydroxyphenylacetic acid（9）,methyl 4-hydroxyphenylacetate（10）.Among them,the compound cyclo（L-Phe-L-Phe）（3）was isolated for the first time in Aspergillus fumigatus SZW01.Through reading and analyzing the previous literature,the research group found that the compound cyclo（L-Phe-L-Phe）（3）has more significant biological activity in antibacterial and antitumor aspects.Has excellent application prospects and research value.The above 10 compounds were tested for antibacterial activity.The following results were obtained by the microdilution method.Compounds 2 and 3 showed inhibitory activity against Escherichia coli（E.coli CMCC（B）44102）,with MIC values of 62.5μg/m L and 125μg/m L,respectively.Compounds 2 and 3 also inhibited the growth of Staphylococcus aureus（S.aureus CMCC（B）26003）,with MIC values of 62.5μg/m L and 125μg/m L,respectively.All the other tested compounds above,such as Compound 1 and Compounds 4 to 10,are in the bacteria Escherichia coli（E.coli CMCC（B）44102）,Staphylococcus aureus（S.aureus CMCC（B）26003）,Bacillus subtilis（B.subtilis CMCC（B）63501）and the fungus Candida albicans（C.albicans CMCC（F）98001）showed almost no inhibitory activity.