Study On The Secondary Metabolites From Fungus HNWSW-20 And Actinomycetes KM1

The secondary metabolites of microorganisms have a wide variety of structure skeletons and extensive bioactivities,such as antimicrobial,antitumor,antiviral and immunosuppressive,which are the important sources of drug leading compounds.They have played important role in medicine,agriculture and industry.The discovery of compounds with novel structures and outstanding biological activities is one of the important purposes in the research of microorganisms.Fungi and actinomycetes are important members of microbes,which are the source of a large number of bioactive compounds,and have played important roles in the human life.In this paper,six fungi HNWSW-20-HNWSW-25 derived from Chinese agarwood as well as a soil(collected in Danzhou,Hainan)derived actinomycetes KM1 were isolated.The results from HPLC and TLC analysis showed that the secondary metabolites from fungal strain HNWSW-20 and actinomycetes KM1 were very rich,and worth for further research.The fungus HNWSW-20 and the actinomycetes KM1 were identified as Aspergillus fumigatus and Streptomyces durhamensis by morphology and molecular biology,respectively.Fermentation conditions were optimized according to the antimicrobial activity,as well as HPLC and TLC analysis.Accordingly,PDB was used as the fermentation medium of strain HNWSW-20 in this experiment,and the fermentation time was 50 days.While liquid fermentation and Gause's No.1 synthetic medium as the fermentation medium for KM1,and the fermentation time was selected as 20 days.The secondary metabolites were isolated and purified by various chromatographic techniques,and then the structures of the compounds were identified on the basis of spectroscopic evidence and physicochemical properties.The acetylcholinesterase and a-glucosidase inhibitory activities of the compounds were determined by Ellman colorimetric assay and pNPG method,respectively.Nine compounds were isolated from the fungus A.fumigatus HNWSW-20 and their structures were determined as:neocyclocitrinols E(1),2',3'-dihydrosorbicillin(2),sorbicillin(3),(2R)-2,3-dihydro-7-hydroxyl-6,8-dimethyl-2-[(E)-prop-1-enyl]chromen-4-one(4),11-hydroxy-1-methoxycar-bonyl-9-methylxanthone(5)7-hydroxy-1(3H)-isobe-nzofuranone(6),dibutylphthalate(7),(-)-clovane-2,9-diol(8)and eicosanoic acid(9).Four compounds was isolated from the S.durhamensis KM1,and the structures were determined as:1-methyl-1,4-dihydroquinoxaline-2,3-dione(10),5-hydroxymethylfuran-3-carboxylic acid(11),uracil(12),thymine(13)and 7,8-dimethylalloxazine(14).Compounds 2,3 and 7 showed acetylcholinesterase inhibitory activity;Compounds 2,4 and 6 exhibited a-glucosidase inhibitory activity.Compound 1 is a new compound.Compounds 2?4 were isolated from A.fumigatus for the first time,and this was the first report about their acetylcholinesterase and a-glucosidase inhibitory activities.