Studies On The Secondary Metabolites Of Two Strains Of Fungi

Fungi growing in special environments tend to produce bioactive secondary metabolites with plenty of structure characteristics.Dueto their evolutional and differential metabolic systems,fungi highly adapted to extreme environment during the process of natural selection.Fungi are a rich resourcein the nature;its unique metabolic pathways make fungi produce a lot of important precursor drugs.Sincethe beginning of systematic analysis of the secondary metabolites of funginearly a century ago,the researchers found that the small molecule secondary metabolites have different biological activities.The most systematically researches wereon compoundswithdrug development potential,including antibacterial,antifungal,antiparasite,antiviral,and even antitumor activity.Fungi secondary metabolites provide high quality of compounds resourcefor innovative drug development.At the same time,the biological small molecules probesare great significance to the study onnormal biological activities of organism.Based on the above reasons,we hoped to get in-depth chemicalinvestigation onsome domestic fungiin special growth environment.By using many kinds of chromatographical and spectral techniques including silica gel thin-layer chromatography,silica gel column chromatography,sephadex LH-20 column chromatography,high performance liquid chromatography?HPLC?separation,mass spectrometry,nuclear magnetic resonance?NMR?spectroscopyanalysis,we studied secondary metabolites ofStagonospora trichophoricola from the soil sample surrounding the fruiting body of Ophiocordycepssinensis in Maqin Country,Qinghai Province,andPhomopsissp.,a plant endophyte of Ternstroemia gymnantherafrom Gutian,Fujian Province,the People's Republic of China.Twenty purecompounds were isolated from the crude extract of rice fermentation.Thirteen compoundswere obtained,including five new compounds.The antibacterial activeity and the cytotoxic activity were tested for all new compounds.Seven compoundswere isolatedfrom theethyl acetate extract of fungusS.trichophoricolain rice fermentation,including linear peptides compounds trichopeptide A?1?,trichopeptide B?2?,diketopiperazines compoundstrichocyclodipeptidesA–C?3–5?,solerone?6?and 13-hydroxy-14-oxocacalohastin?7?,1-5were new compounds.Compounds 1-5were tested forantimicrobialactivity against the fungusCandida albicans,the gram-positive bacteriumStaphylococcus aureus,the gram-negative bacteriumEscherichia coli and the Bacillus subtilis,respectively.Compound3 showedantifungal activity againstC.albicanswith the IC₅₀ and MIC values of 22 and 90?g/mL,respectively.Compounds 2 and 5showed antibacterial activity againstS.aureuswith the IC₅₀ values of 45 and 43?g/mL,respectively.Compounds 3 and 5showedthe antibacterial activity againstB.subtiliswith the IC₅₀ values of 46 and 44?g/mL,respectively.Six known compounds were isolated from the ethyl acetate extract of fungus Phomopsis sp..The compounds areidentified as convolvulopyrone?1?,isorhodoptilometrin?2?,mellein?3?,5-methylmellein?4?,11-hydroxy-4,6-dimethyl-2,4-dodecadienoic acid?5?and cytosporone C?6?.