Study On The Secondary Metabolites Of Aspergillus Flavus And The Cytotoxic Activity Of HepG2

Aspergillus is one of the common fungi groups on the earth,composed of more than 300 species of bacteria,and their lifestyles are complex and diverse.Many strains of Aspergillus have high utility value in traditional fermentation industry,modern fermentation industry and many bioengineering fields.In addition,many Aspergillus species can cause spoilage and deterioration of crops and food.A small number of Aspergillus can also produce a variety of mycotoxins.Most of the secondary metabolites of Aspergillus species have cytotoxic,antibacterial,antiviral,and anti-infective activities.In order to find compounds with good biological activity and novel struct ures,this thesis conducted a systematic chemical composition study on the sec ondary metabolites of Aspergillus flavus rice culture medium,and tested some compounds with cytotoxic biological activity using MTT method.Separation an d purification of the secondary metabolites of Aspergillus flavus rice culture m edium using laboratory separation techniques such as dextran gel column chro matography,reversed phase C-18 column chromatography,MCI gel column chr omatography,silica gel column chromatography,etc.Using¹H NMR,¹³C NMR,NOE,¹H-¹H COSY,HSQC,HMBC and other modern spectroscopy techniques,and by consulting relevant literature for comparison,the structure of 18 comp ounds were identified,including polyketones,esters,and quinones And alkaloid compounds,their structures are:methylradiclonate（1）,1,7-dihydroxy-3-（hydroxy methyl）-8-methoxydibenzo[b,e]oxepine9,10-dione（2）,6,8,1’-tri-O-methylaverantin（3）,methyl-averantin（4）,8-O-methylaverythin（5）,6,8-O-methylaverantin（6）,noto amides C（7）,fischexanthone（8）,AGI-B4（9）,averantin（10）,1-hydroxy-3-（hydroxy methyl）-8-methoxydiphenylpropan[b,e]oxazepine9,10-dione（11）,3-hydroxy-5-met hybenzonicacid（12）,6-methylbenzene-1,2,4-triol（13）,7,9-dihydroxy-3-methoxy-1-methyl-6h-dibenzo[b,d]pyran-6-one（14）,（E）-5-（hydroxyniethyl）-2-（6’-methy1hept-2-en-2’-yl）pheno（15）,diorcinol（16）,4-hydro xy Methyl phenylacetate（17）,4-methox ybenzylmehano（18）,of which compound 1 is a new compound,and compoun ds 2,3,4,5,and 6 are polyketides isolated from Aspergillus flavus for the fir st time.The cytotoxic activity of the isolated compounds 1,3,4,8,9 and 10were studied by the MTT method.The results showed that compound 9 has g ood cytotoxic activity on human liver cancer cells HepG2.When the sample c oncentration was 100μg/m L and the drug treatment time was 24 hours,the in hibition rate was 84.91%,and none of the other compounds showed obvious c ytotoxic activity.The results of the study on the secondary metabolites of Asper gillus flavus in this paper are expected to enrich the database of natural produ cts,provide support for the development and utilization of this genus of fungi,and contribute to the development and utilization of natural product resources.