| Ocean as a separate distinct from terrestrial ecosystems, its unique ecological environment created the diversity of novel chemical structures and biological activities of marine source microbial. As an important part of marine microorganisms, the fungi resources, because of its huge potential metabolism, had become an important source for natural medicinal chemists finding active new drug lead compounds. In this paper, six marine-derived fungi were determined as studied strains for their secondary metabolites. Studies include isolation and screening of anti-tumor fungal strains, purification and structural elucidation of secondary metabolites, exploring the biosynthetic pathways of novel compounds, preliminary evaluation for bioactivities of pure compounds and strain metabolic potential mining.300 fungal strains were isolated from 16 Guangdong and Guangxi mangrove roots soil samples, Using the fungal morphology differences together with the TLC, HPLC chemical screen assays and P388 cell line cytotoxicity assayas,26 fungal strains were detected as potential strain. Among the bioactive strains, two Guangdong mangrove-derived fungi penicillium chrysogenum HDN11-24 and Aspergillus flavus HDN11-47; Two Guangxi mangrove-derived fungi Aspergillus sp. HDN11-84 and Sarocladium kiliense HDN11-112; a Jiaozhou Bay derived fungus Aspergillus westerdijkiae HDN13-512 and a deep sea derived fungus Penicillium sp. F23-2 were picked out as the potential fungal strainsAll the secondary metabolites from the six aimed fungi used the gel column, Sephadex LH20, HPLC for the isolation and expurgation of 89 natural products. From fungus penicillium sp. F23-2,14 compounds (1-14) were isolated in the culture condition of PYG,12 compounds (15-26) were purified from rice sediment and 4 compounds (27-30) were isolated from the mutant strain; 16 compounds (31-46) were purified from fungus Aspergillus sp. HDN11-84; 5 compounds (47-51) were isolated from fungus Sarocladium kiliense HDN11-112; 9 compounds (52-60) were isolated from fungus Aspergillus westerdijkiae HDN 13-512; 16 compounds (61-76) were isolated from fungus penicillium chrysogenum HDN 11-24; 13 compounds (77-89) were isolated from fungus Aspergillus flavus HDN 11-47.While all the 89 isolated natural products were using mass spectrometry, nuclear magnetic resonance spectroscopy (NMR), infrared spectroscopy and UV spectroscopy, physical and chemical properties of the compound as well as circular dichroism. X-ray diffraction and chemical reaction methods to verify the chemical structures. Among them there are 36 alkaloids (9-10,20-24,27-29,31-46,47-48,52-53,70, 73-75,89),41 polyketides (1-8,11-19,25,30,49-51,54-69,71-72,76),8 diterpenes (77-84) and 4 other structural type compounds (85-88). There were forty-two new compounds and two new natural products, including 5 novel sorbicilline alkaloids (1-5), I new dimer sorbicilline (25),5 new cyclohexenones (15-19),2 new NRPS-PKS compounds (47-48),3 novel citrinin (61-62,64),1 new xanthones (63),5 new lactone derivates (54-58),1 new steroid (77) and 5 other kind alkaloids (24, 28-29,52-53). In the study, the relative and absolute configurations of sorbicilline alkaloids and citrinin derivates (1-5,61,64) were determined by the combination of NOESY, ECU calculation and the possible biogenetic deduction. The relative and absolute configurations of 2 new NRPS-PKS compounds (47-48) were determined by NOESY, Marfy’s method and X-ray diffraction. The absolute configurations of 1 new steroid (77) was confirmed by the X-ray diffraction.In order to find potential lead compounds, and explore the biological activity of the isolated natural products, the assays of antitumor and antibacterial activities were evaluated and screened. Several natural products were evaluated for the cytotoxicities against several cancer cell lines, such as Hela, BEL-7402, HEK-293, HCT-116 and A549, by using the MTT and SRB methods. Among them,7 compouds showed different levels of cytotoxicities, on the other hand, the paper method was used for the antimicrobial activity screening. As a result, the IC50 values of 1 against HCT116 was 10.0μM; compounds 47 and 48 against A549 with the IC50 values 4.5/μM and 6.0μM. respectively; compounds 47 and 48 against Hela, BEL-7402, HEK-293, HCT-116, A549 with the IC50 3.2～10.5μM; compound 77 exhibited good activity of IC50 values 6.4μM to HL-60, and compounds 15-19 exhibited good activities against staphylococcus aureus.In summary, this thesis focus on the isolation of secondary metabolites from six different sources of marine habitats fungal fermentation in the laboratory conditions, 89 natural products were obtained, including 35 new compounds and two new natural products. In the study of the new structures of the, the method of computed the ECD was used to the sorbicilline alkaloids for the first time, and found the good cytotoxic activity of 1. Discovered a series of active cyclohexenones with anti-Staphylococcus aureus activity; also found the anti-tumor activity to the PKS-NRPS hybrid of macrolide compounds. The above experimental studies provides a new direction to determine the chemical structure of the natural products research, and may find potential new drug compounds served as lead compounds. |
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