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Four unprecedented polyketides named isoprenylisobenzofuran B (<b>2</b>), isoprenylisobenzofuran C₁/C₂ (<b>3</b>), diaporisoindole F₁/F₂ (<b>4</b>), and isochromophilonol A₁/A₂ (<b>7</b>) were isolated from ethyl acetate extracts of the newly described endophytic fungus <i>Diaporthe africana</i>. Additionally, the previously reported cyclic depsipeptide eucalactam B (<b>1</b>) was also identified, along with the known compounds diaporisoindole A/B (<b>5</b>), tenellone B (<b>6</b>) and beauvericin (<b>8</b>). The taxonomic identification of the fungus was accomplished using a polyphasic approach combining multi-gene phylogenetic analysis and microscopic morphological characters. The structures <b>1</b>–<b>8</b> 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 <b>1</b>. All the compounds obtained were evaluated for antimicrobial and in vitro cytotoxic properties. Compounds <b>3</b>–<b>8</b> were active against certain fungi and Gram-positive bacteria with MIC values of 8.3 to 66.6 µg/mL. In addition, <b>3</b>–<b>5</b> displayed cytotoxic effects (22.0 ≤ IC₅₀ ≤ 59.2 µM) against KB3.1 and L929 cell lines, whereas compounds <b>6</b>–<b>8</b> inhibited the growth of seven mammalian cancer cell lines with IC₅₀ ranging from 17.7 to 49.5 µM (<b>6</b>), 0.9 to 12.9 µM (<b>7</b>) and 1.9 to 4.3 µM (<b>8</b>).