Diphenyl Ether Derivative Rhexocerins and Rhexocercosporins from the Endophytic Fungus <i>Rhexocercosporidium</i> sp. Dzf14 Active against Gram-Positive Bacteria with Multidrug-Resistance

Abstract

Ten new diphenyl ether polyketides, including rhexocerins A-D (<b>1</b>-<b>4</b>) and rhexocercosporins A-F (<b>5</b>-<b>10</b>), together with three known congeners (<b>11</b>-<b>13</b>), were isolated from the endophytic fungus <i>Rhexocercosporidium</i> sp. Dzf14 obtained from <i>Dioscorea zingiberensis</i>. Their structures were elucidated by analysis of NMR and HRESIMS data, and their absolute configurations were determined by quantum chemical ECD calculations and X-ray crystallography. Compounds <b>1</b>-<b>4</b> featured an unprecedented tetracyclic carbon skeleton (6/7/5/6). Among them, compounds <b>1</b> and <b>5</b>-<b>9</b> showed antibacterial activities against methicillin-resistant <i>S. aureus</i> T144 and vancomycin-resistant <i>E. faecalis</i> 10.