Secondary Metabolites Of Two Marine Fungal Strains Associated With Coral

Because of the special living environment, coral possess distinct and complex metabolic capabilities, resulting in wide diversity of their secondary metabolites in chemical structure and biological activity. Most of these secondary metabolites are possibly resulted from their symbiotic microorganisms. This thesis describes the screening of symbiotic fungi and studies on the secondary metabolites produced by two selected talented fungal strains from coral. Studies include isolation of symbiotic fungi from coral samples, screening of talented strains, optimization of fermentation, bioassay-guided fractionation, structural elucidation and cytotoxicity evaluation.Five talented strains were obtained by integrated cytotoxic and chemical screening methods from 168 fungi isolated from corals collected from Linshui, Sanya, Lingao, Wanninggang, Weizhou, Zhanjiang, China. Because of cytotoxicity and a series HPLC peaks with similar UV absorption, Aspergillus versicolor LCJ-5-4 and Penicillium sp. gxwz406 were selected as working strains for further study of secondary metabolites. Guided by bioactivity, the active fractions were subjected to chromatography over silica gel, Sephadex LH-20 and prepared TLC, and preparative HPLC to afford 16 compounds from Aspergillus versicolor LCJ-5-4. By the same procedure,5 compounds were isolated and identified from Penicillium sp. gxwz406. By means of spectroscopic and chemical methods, their structures were elucidated as: aspertides A-C (1-3), cottoquinazolines B-D (4-6), glyantrypine (7), (Z)-5-(2,3-dihydroxybutylidene)furan-2(5H)-one(8), (E)-5-(2,3-dihydroxybutylidene) furan-2(5H)-one (9), tetraorcinol (10), diorcinol (11), cordyol C (12), versicolorin B (13), 1,3,6,8-Tetrahydroxy-9,10-anthraquinone (14), versicol (15), averufanin (16); S(-)-2-(2-hydroxypropanamido)benzamide (17),R(+)-chrysogine (18),2-pyruvyl aminobenzamide (19), nicotinamide (20), and 2',3'-dihydrosorbicillin (21)。Among them, compounds 1-6 and 8-10 are new compounds.The cytotoxicity of these compounds against two cancer cell lines was evaluated by MTT method. Compound 19, one of the main metabolites from Penicillium sp. gxwz406 exhibited cytotoxicity against P388 and Hela cells with IC50 values of 10.6μM and 15.6μM, respectively.In a word, nine new compounds together with twelve known ones were isolated and identified from the two symbiotic fungi with corals. Studies mentioned above provide novel structures for searching new leading compounds and microbial resources for further study and it proves the method we used is effective in finding new active compounds.