Study On Bioactive Secondary Metabolites From Two Marine Animal Symbiotic Fungi

Gut symbiotic fungi,a major group of special microorganisms,can produce novel bioactive compounds and is an important source of new bioactive natural products.In order to obtain new secondary metabolites with novel structures and bioactivities,two strains of symbiotic fungi 5XNZ5-4 from marine crab’s gut and RP04 from marine isopod Ligia oceanica,were chosen to investigate the secondary metabolites of them.20 compounds were isolated and purified by various chromatograohic methods such as thin layer chromatography,column chromatography,HPLC.14 of compounds,isolated from fungus Arthrinium sp.5XNZ5-4,were identified by spectral analysis of NMR,MS,UV,IR,and CD.These 14 compounds included six indone derivatives,four sesquiterpenoids,two diphenylketones,one anthrone and one aromatic ketone.And compounds 1-9 are new ones.The other six compounds were isolated from the marine isopod Ligia exctica symbiotic fungus RP04,and their structures were identified by the same method,which included two resorcinol derivatives,two citrinin dimers,one diphenylketone,and one anthraquinone.Antibacterial activities of all compounds were tested by Kirby-Bauer Paper flakes diffusion method,and the results indicated that all of them showed no abvious activity.In addition,the cytotoxic activity of 1-10 compounds was tested using MTT method.The result showed that the compounds 2 and 3 have weak activity inhibiting PC3 cell,while other compounds have no cytotoxicity.IC50 value of compound 3 was 60 μM,while compound 2 showed the inhibition rate 37.4%at the concentration of 10 μg/mL.In conclusion,nine new compounds have been found,including three sesquiterpenoids and six indone derivatives.Compound 3 contained novel indone structure,and showed moderate biological activity inhibiting the cancer cells.