| Summary: | 碩士 === 國立臺灣大學 === 漁業科學研究所 === 107 === Among the mairne microorganisms, marine-derived fungi are able to produce lots of secondary metabolites with highly structural diversity. The discovery of new natural products from marine-derived fungi has increased dramatically over the last few decades, and some of them revealed great potentials for drug developments. In our preliminary screening, the bioactivities of 343 fungal strains, isolated from marine macroalgae collected from northeast coast of Taiwan, were tested intensively. Of these, the ethyl acetate extract of the fermented broth of Aspergillus sp. NTU967, isolated from a marine green alga Ulva lactuca, was found to exhibit significant antimicrobial activities against Staphylococcus aureus and Cryptococcus neoformans. Therefore, bioassay-guided separations of the active principles from liquid- or solid-state fermentations of Aspergillus sp. NTU967 were carried out, and which have led to isolation and purification of compounds 1 – 13 . Their structures were elucidated by spectroscopic analysis to be eight new aspergilsmins A − H (1 − 7 and 13), together with five previously reported clavatol (8), deoxytryptoquivaline (9), tryptoquivaline (10), quinadoline B (11) and (4-oxo-5,6-dihydro-4H-pyran-3-yl)-acetic acid (12). Aspergilsmins E (5) and F (6) exhibited significant growth inhibition against Staphylococcus aureus with the minimum inhibitory concentration (MIC) of 32 μg/ml. Aspergilsmin C (3) showed cytotoxic activity against prostate cancer cells (PC-3) and hepatocellular carcinoma cells (SK-Hep-1), and the half inhibitory concentrations (IC50) were 7.3 ± 0.3 and 2.7 ± 0.2 μM, respectively. The detailed mechanism of compound 3 against cancer cells remains to be confirmed by further experiments.
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