New Phenanthrene Derivatives from <i>Cylindrolobus mucronatus</i> Lindl. and their Cytotoxic Activity against Glioblastoma Cells

A detailed phytochemical investigation was carried out on the whole plant of <i>Cylindrolobus mucronatus</i>, representing the first scientific study of this species. The research identified 11 compounds, including four newly discovered structures, cymucronins A-D (<b>1-4</b>), and seven previously known compounds (<b>5-11</b>). The structures of the new compounds were determined using advanced spectroscopic methods, such as nuclear magnetic resonance (NMR) and mass spectrometry. The cytotoxic activities of isolated compounds (<b>1-3</b>, <b>5-9</b>) were tested against the U-87 MG glioma cell line. The half-maximal inhibitory concentrations (IC₅₀) of compounds <b>3</b> and <b>9</b> were 19.91 ± 4.28 and 17.08 ± 3.72 μM, respectively, indicating the potential of <i>C. mucronatus</i> as a valuable source of cytotoxic natural products. This study provides significant insights into the phytochemical and pharmacological properties of <i>C. mucronatus</i>, supporting its potential for further exploration in anticancer medicinal research.