| Natural products have long been recognized as valuable in treating cancer,infectious diseases and other areas.Endophytic fungi asymptomatically colonize healthy plant tissues and have complex associations with host plants,parasites,pathogens and other associated microorganisms.This particular interplay enables the production of secondary metabolites by endophytic fungi with features of backbone novelty,special biosynthetic pathways and diversity of biological activities.The two fungi are derived from great Mahonia fortunei medicinal plant,and the plant belongs to the family berberiaceae in the phylum angiosperm,which is a traditional medicinal plant in China.Modern research has found that its chemical components have anti-inflammatory,anti-tumor,anti-oxidation and other effects.In this work,the OSMAC(one strain many compounds)strategy was used to inoculate two M.fortune-derived endophytic fungi by small-scale fermentation using four different media including rice,soybean media,corn media and Czapek Dox Agar(CDA).After that,the fermentation products of the strains were extracted with ethyl acetate and the crude extracts were analyzed by high performance liquid chromatography(HPLC).The crude extracts of strains with a lot of number of peaks in HPLC analysis were screened out for resistance against plant pathogens to find strains that produced secondary metabolites with novel structure and good bioactivity.The Fusarium decemcellulare F25 was subjected to large-scale fermentation in rice peptone medium.The fermented crude extract was subjected to ethyl acetate ice bath ultrasonic extraction,after which the ethyl acetate layer crude extract was suspended in water and extracted with petroleum ether and ethyl acetate,respectively.The crude extract from the ethyl acetate layer was subjected to ODS-C18 column chromatography,silica gel column chromatography,preparative HPLC,and other chromatographic methods.The structures of isolated compounds were elucidated by1 D and 2D NMR,electron circular dichroism(ECD),X single crystal diffraction(X-ray),and their physicochemical properties.20 compounds were isolated from the ethyl acetate extract of F.decemcellulare F25.They were identified as isocoumarins(1–7),pyrrolidones(8–11),cyclic lipopeptides(12–14),pentaene diacids(15–17),and other compounds(18–20).Among them,compounds 1,2,3,8,9,10,and 15 were new compounds.All the compounds were tested against plant pathogens.And the MIC values of compounds 13,14,and 17 against Colletotrichum musae ACCC 31244 were 256,64,and 128 μg/m L,respectively.The MIC of the positive control cycliheximide was 32 μg/m L.Drug susceptibility assays were employed to test the inhibitory activities of isocoumarins 1–7 as well as pyrrolidones 8–11 against the human pathogenic bacteria Pseudomonas aeruginosa ATCC10145 and Staphylococcus aureus ATCC43300.Drug susceptibility test results showed that compounds 1–11exhibited no antibacterial activity against two human pathogenic bacteria at concentration of 0.1 mg/m L.The findings demonstrate that secondary metabolites from M.fortune-derived endophytic fungi exhibit structurally novel features and provide a theoretical basis for the search for lead compounds with biological activity from the M.fortune endophytic fungal resources. |
