Secondary Metabolites Of Two Endophytic Fungi From Mediterranean Ascidian And Sponge And Their Bioactivities

Because of unique high salt and oligotrophic environment,Mediterranean Sea become one of the main regions for natural products research.Recently,researches on the secondary metabolites of marine animal-derived microorganisms continuously increased.This thesis systematically investigates and analyzes the natural products of marine animal-derived fungi from the Mediterranean Sea since 2000.Statistical analysis found that the main types of those natural products are polyketones and terpenes,respectively accounting for 49%and 25%,the total amount of other types of compounds is about 26%,which generally exhibited antibacterial,antitumor,and enzyme inhibitiory activities.Furthermore,the proportion of polyketides with biological activity has rised to 53%.It has been proved that the Mediterranean Sea is a huge treasure resource of active natural products and has great research potential.Cultivation of the fungal strain Aspergillus ustus TK-5,which was isolated from the fresh tissue of Mediterranean ascidian Pyura momus,resulted in the identification of 27 compounds,including eight meroterpenoids（AU 1–8）,ten sesquiterpenoids（AU9–18）,seven sesquiterpenes（AU 19–25）,one triterpenoid（AU 26）,and one diketopiperazine（AU 27）.The meroterpenoids（AU 1–3）were identified as new compounds by NMR and single crystal diffraction,and their biogenic pathways were speculated.The secondary metabolites of Aspergillus tamarii TK-18 isolated from Mediterranean sponge Ircina oros were studied.Six compounds（AL 1-6）were isolated and identified from their fermentation products,including sterols and diketopiperazines.All terpenes were tested for neuraminidase inhibitory and acetylcholinesterase inhibitory activity.AU 1,AU 2,AU 4,AU 6,and AU 7 were found to be highly active for neuraminidase,with IC₅₀ values of 5.28,8.95,5.71,1.37,8.95μM.The antibacterial activity of meroterpenoids was evaluated and it was found that only AU 4（MIC=8.0μg/mL）had significant antibacterial activity against Fusarium graminearum.In summary,the identification and biological activities of compounds from two fungi which from Turkish sea ascidian and sponge further confirmed the diversity of the chemical structures and biological activities of metabolites from Mediterranean-derived fungi.It enriches the research content of marine natural products and provides a certain theoretical and experimental basis for the development and utilization of marine biological resources.