AculeapyridonesA‑Q, Pyranopyridone Alkaloidswith Protective Effects against Acetaminophen-Induced Acute LiverInjury Discovered from a Coculture of <i>Aspergillus aculeatinus</i> WHUF0198 and a <i>Penicillium</i> sp.

In the search for novel natural products with hepatoprotective effects against acetaminophen-induced acute liver injury, the marine-derived fungus <i>Aspergillus aculeatinus</i> WHUF0198 was investigated. Seventeen undescribed pyranopyridone alkaloids, aculeapyridones A–Q (<b>1</b>–<b>17</b>), were isolated by bioactivity-guided fractionation of an extract obtained by coculture of the <i>A. aculeatinus</i> WHUF0198 with the mangrove-associated fungus <i>Penicillium</i> sp. DM27. Notably, compounds <b>12</b>–<b>15</b>, which possessed a unique <i>N</i>-methoxy group, were identified as activation products of fungal coculture in liquid media. The structures and absolute configurations of these compounds were elucidated using a combination of universal spectroscopic techniques (NMR and HR-ESI-MS), ECD calculations, and single crystal X-ray diffraction analysis. All the isolated compounds, except <b>8</b> and <b>17</b>, were evaluated for their hepatoprotective activity against acetaminophen-induced acute liver injury <i>in vitro</i>. Compounds <b>1</b>–<b>7</b>, <b>9</b>, <b>10</b> and <b>12</b>–<b>15</b> increased cell viability and reduced alanine aminotransferase (ALT) levels of acetaminophen-induced murine hepatocytes at either 5 or 10 μM.