Unprecedented Antimicrobial and Cytotoxic Polyketides from Cultures of sp. nov.

Four unprecedented polyketides named isoprenylisobenzofuran B (), isoprenylisobenzofuran C/C (), diaporisoindole F/F (), and isochromophilonol A/A () were isolated from ethyl acetate extracts of the newly described endophytic fungus . Additionally, the previously reported cyclic depsipeptide eucalactam B () was also identified, along with the known compounds diaporisoindole A/B (), tenellone B () and beauvericin (). The taxonomic identification of the fungus was accomplished using a polyphasic approach combining multi-gene phylogenetic analysis and microscopic morphological characters. The structures - were determined by a detailed analysis of their spectral data, namely high-resolution electrospray ionization mass spectrometry (HR-ESIMS), 1D/2D nuclear magnetic resonance (NMR) spectroscopy, as well as electronic circular dichroism (ECD) spectra. In addition, chemical methods such as Marfey's analysis were also employed to determine the stereochemistry in compound . All the compounds obtained were evaluated for antimicrobial and in vitro cytotoxic properties. Compounds - were active against certain fungi and Gram-positive bacteria with MIC values of 8.3 to 66.6 µg/mL. In addition, - displayed cytotoxic effects (22.0 ≤ IC ≤ 59.2 µM) against KB3.1 and L929 cell lines, whereas compounds - inhibited the growth of seven mammalian cancer cell lines with IC ranging from 17.7 to 49.5 µM (), 0.9 to 12.9 µM () and 1.9 to 4.3 µM ().