Study On Secondary Metabolites From The Fungi Paraconiothyrium Sporulosum

There are abundant microbial resources in the special ecological environment of the ocean.The marine microorganisms have been the focus of intensive chemical investigation in recent years since they have proven to be rich source of unique and biologically active metabolites.In this study,40 strains of the marine fungi were isolated from Bohai Bay in Liaoning Province of China.Several ideal strains were discovered by chemical and biological activity screening.The fermentation products of the strain DL-16 showed significant antibacterial and tumor cytotoxic activities,and containing diverse secondary metabolites.The strain DL-16 was identified as Paraconiothyrium sporulosum according to a molecular biological protocol by DNA amplification and sequencing of the ITS region.However,there are few reports on this species.Herein,we report their isolation,structural elucidation and biological activities.The strain DL-16 was fermented on a large scale,and extracted with organic solvent to obtain the crude extract.Chemical investigation of the extract led to the identification of twenty compounds,including thirteen eremophilane sesquiterpenoids（1-13）,some of them were dimeric or rearranged,three isocoumarins（14-16）,three tetrahydroquinones（17-19）and one anthraquinone（20）.All of the compounds were elucidated by spectroscopic and spectrometric analyses,including NMR,UV,IR,HRESIMS,the values of optical rotation,ECD,X-ray,and by comparison with literature data.It is worth mentioning that 1-8,12 and 13 are new eremophilane sesquiterpenoids,1,2 and 4 are the first examples of dimeric eremophilane sesquiterpenoids identified from microorganisms.The antifungal,antibacterial,tumor cytotoxic and anti-inflammatory activities of the isolated compounds were tested.5 and 8 showed weak antifungal activity.2,3,5-10 showed varying levels of antibacterial activity against different tesed strains（due to the limited mass of some samples,the antibacterial activity of 1,4,11-13 were not tested）,however,the non-sesquiterpenoids（14-20）were inactive,which indicated that the eremophilane sesquiterpenoids were the active components.8 showed weak cytotoxic activity against AGS cells.2-10 showed inhibition effects on lipopolysaccharideinduced NO production in BV-2 cells,2-5,8 and 10 were the most potent with IC50 values that range from 2.8±0.5 μM to 8.1±3.5 μM,which is comparable to the positive control curcumin（8.6±1.6 μM）.In conclusion,twenty compounds were isolated and identified from the fermentation products of P.sporulosum,including ten new eremophilane sesquiterpenoids,and some of the compounds showed anti-bacterial,tumor cytotoxic and anti-inflammatory activities.The present study made up for the lack of research on secondary metabolites of P.sporulosum,enriched the structural types of eremophilane sesquiterpenoids,and provided a model structure for the development of antibacterial and anti-inflammatory drugs.