Acetylcholinesterase Inhibitory Meroterpenoid from a Mangrove Endophytic Fungus Aspergillus sp. 16-5c

Abstract

One new meroterpenoid, named 2-hydroacetoxydehydroaustin (<b>1</b>), together with nine known meroterpenoids, 11-acetoxyisoaustinone (<b>2</b>), isoaustinol (<b>3</b>), austin (<b>4</b>), austinol (<b>5</b>), acetoxydehydroaustin (<b>6</b>), dehydroaustin (<b>7</b>), dehydroaustinol (<b>8</b>), preaustinoid A2 (<b>9</b>), and 1,2-dihydro-acetoxydehydroaustin B (<b>10</b>), were isolated from the mangrove endophytic fungus, <i>Aspergillus</i> sp. 16-5c. These structures were characterized by spectroscopic analysis, further the absolute configurations of stereogenic carbons for Compounds <b>1</b>, <b>3</b>, <b>4</b>, <b>6</b>, <b>7</b>, <b>8</b>, <b>9</b>, and <b>10</b> were determined by single crystal X-ray diffraction analysis using Cu Kα radiation. Moreover, the absolute configurations of stereogenic carbons for Known Compounds <b>3</b>, <b>7</b>, <b>8</b>, and <b>9</b> are identified here for the first time. Compounds <b>3</b>, <b>7</b>, and <b>8</b> showed acetylcholinesterase (AchE) inhibitory activity with IC₅₀ values of 2.50, 0.40, and 3.00 μM, respectively.