Paraconfuranones A–H were obtained from fermentation extract of fungus Paraconiothyrium brasiliense inhabiting the Acrida cinerea. Their structures were elucidated on the basis of 1D and 2D NMR spectroscopy.
Ten secondary metabolites (1-10) including a new 4-hydroxycinnamic acid derivatives, methyl 2-{(E)-2-[4-(formyloxy)phenyl]ethenyl}-4-methyl-3-oxopentanoate (1), and nine known compounds (2-10) were isolated from an EtOAc extract derived from a solid rice medium of endophytic fungal strain Pyronema sp. (A2-1 & D1-2). Their structures were elucidated from NMR and HRMS data. All the compounds were tested for antibacterial activity against Mycobacterium marinum ATCCBAA-535. Compounds 1, 8 and 9 exhibited moderate antibiotic activity with IC of 64, 43 and 32 μM, respectively.
Seeking a strategy for triggering the cryptic natural product biosynthesis to yield novel compounds in the plant-associated fungus Xylaria sp., the effect of culture conditions on metabolite production was investigated. A shift in the production of five known cytochalasin-type analogues 1-5 to six new α-pyrone derivatives, xylapyrones A-F (compounds 6-11), from a solid to a liquid medium was observed. These compounds were identified by analysis of 1D and 2D NMR and HRMS data. Compounds 1-3 showed moderate cytotoxicity against HepG2 and Caski cancer cell lines with IC50 values ranging from 25 to 63 μM and compounds 4-11 were found to be inactive, with IC50 values >100 μM.
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