Endophytic Fungus From Thalictrum Baicalense Turcz.:Isolation,Purification And Bioactivity Study On The Secondary Metabolites

In recent years,endophytes from medicinal plants are potential resources for new natural products and the development of new drugs,and have important research and development value.There are abundant medicinal resources in Gansu Province,but the fewer researches are reports on endophytes from plants.Therefore,Thalictrum baicalense Turcz from Gansu was chosen to carry some preliminary researches on purification biological activity and the secondary metabolites of endophytic fungi.The main research contents and results were as follows:18 strains were isolated from Thalictrum baicalense Turcz,they are identified and classified to be Aspergillus,Acremonium,Fusarium,Epichloe,Alternaria and Stemphylium,the dominant genus of which is Fusarium.The secondary metabolites of 18 endophytic fungi was prepared.The mycelia were extracted by reflux method with alcohol for 2 ~ 3 h.The extract was dried under reduced pressure to obtain the ethanol extract of mycelium.The fermentation broth was extracted by ethyl actrate and n-butanol for three times.The extracts were combined and evaporated to dryness under reduced pressure to obtain the ethyl acetate and n-butanol extractions.Antioxidant and in vitro antibacterial activity of metabolites from endophytic fungi were evaluated by DPPH radical scavenging,hydroxyl radical scavenging,total reducing power and broth microdilution methods,respectively.The antioxidant results showed that the ethyl acetate extracts of the fermentation from various fungi exhibited the best antioxidant activities.Strain Y-3 showed the best DPPH radical scavenging activity with clearance rate of 91.04%,which is closing to that of Vc,J-2 strain showed good hydroxyl radical scavenging activity with clearance rate of 77.86%,Z-6 strain showed good total reducing power,Vc equivalent of samples from Z-6 was190.2 ?g/mg.Antimicrobial activity results showed that the ethyl acetate extract of the fermentation from strain Z-1 exhibited the strongest antimicrobial activity,the MIC against Staphylococcus aureus and Bacillus licheniformis were all 125 ?g/mL and 250 ?g/mL against Klebsiella pneumoniae,Escherichia coli,Streptococcus agalactiae,and Pseudomonas aeruginosa.The n-butyl alcohol extract of the fermentation from strains Z-3 and Z-4 have better antimicrobial activity,the MIC against six test bacteria were 250 ?g/mL;the MIC of ethanol extract from strain Z-7against Staphylococcus aureus,Klebsiella pneumoniae,Escherichia coli andPseudomonas aeruginosa were 500 ?g/mL,and 1000 ?g/mL against Streptococcus agalactiae and Bacillus licheniformis.The compounds from the ethyl acetate fraction of J-2 fermentation broth were isolated by silica gel and sephadex LH-20 colum chromatograph,the structures were analyzed and identified by1H-NMR,13C-NMR,ESI-MS and other modern spectroscopic techniques,respectively.The compound structure was identified as1-palmitoyl-2-9Z-oleoyl-3-9Z,12Z-linoleoyl-glycerol(1).Due to short-time,further isolation and identification,biological estimate of compounds,will be done in the future.