Studies On The Secondery Metabolites And Their Bioactivies Of Porites Pukoensis-Derived Fungi From Xu Wen

Marine bioresources are extremely important for natural drug discovery. Tropicalcoral reef ecosystem which is rich in biodiversity and chemical diversity, especially theirsymbiotic microorganisms depend on the chemical defensive substances, makes animportant resources for the discovery of drug lead compounds. Recently, more and moreattentions are paying in this research field.In this thesis, we have researched on23strains Porites pukoensis coral-derivedfungi from XuWen, five strains have showed the antimicrobial activities. According toHPLC chemical screening, Fusarium fujikuroi XWC21-13were selected for large-scalefementation to accumulated the active secondary metabolites. Then the secondarymetabolites were isolated and identified for further investigation. Most of the isolatedcompounds were preliminary evaluated on their bioactivities and optimal fermentationconditions.In our research,4compounds were isolated from the fermentation extracts of thePorites pukoensis coral-derived fungi (Fusarium fujikuroi XWC21-13) by repeatedcolumn chromatography (CC) on silica gel, RP-18and Sephadex LH-20, as well as bysemi-preparative HPLC, including one macrolides (1) and three unidentified compounds(2-4). Their structures were elucidated by NMR，MS spectroscopy and compared with theprevious data reported in the literature. Compounds1and2were screened for theirantimicrobial and cytotoxic activities. Compounds1showed inhibitory activity againstShewanella sp. SL3and Vibrio parahemolyticus (spoilage organisms from aquaticproduct), with an MIC value both of50μM. In addition, Compounds1showedcytotoxicity against Hela with the IC50value of26.70μM; compounds2showedcytotoxicity against Hela and H460, with the IC50value of55.78μM and62.16μM,respectively.According to the quantitative analysis of (S)-curvularin production in differentfermentation conditions by using HPLC, the fermentation of Fusarium fujikuroiXWC21-13were optimized. As a result, adding500μM SAHA,28℃and fermentestatically for29days, the maximum (S)-curvularin (381.4039μg/ml) was achieved,40.86%highter than the control production. Although the yield of (S)-curvularin has notbeen improved obviously in the shaker (60rpm), the fermentation period has been shorten nearly half by comparing with static fermentation.In this research, we focus on the compouds isolation and bioactivity from a coralassociated fungus. Two compounds have revealed moderate activity to aquatic productspoilage organisms and hela cytotoxic. At the same time, microbial fermentationtechnology has been applied to improving yield of the product, which proved addingSAHA can promote the synthesis of macrocyclic lactones. This strategy can offer ascientific basis for effective utilization of marine microoganisms resources.