Six Unprecedented Cytochalasin Derivatives from the Potato Endophytic Fungus Xylaria curta E10 and Their Cytotoxicity

Abstract

Six previously undescribed cytochalasins, Curtachalasins X1-X6 (<b>1</b>-<b>6</b>), together with six known compounds (<b>7</b>-<b>12</b>) were isolated from the endophytic fungus <i>Xylaria curta</i> E10 harbored in the plant <i>Solanum tuberosum</i>. The structures were elucidated by the interpretation of HRESIMS, UV, and NMR data. The absolute configurations of Curtachalasins X1-X6 were determined by comparison of their experimental and calculated electronic circular dichroism (ECD) spectra. In bioassays, Curtachalasin X1 (<b>1</b>) and X5 (<b>5</b>) showed cytotoxic activity against the MCF-7 cell line with IC₅₀ values of 2.03 μM and 0.85 μM, respectively.