Nitric Oxide Inhibitory Sesquiterpenoids and Its Dimers from <i>Artemisia freyniana</i>

Two new disesquiterpenoids (<b>1</b> and <b>2</b>) and 11 new (<b>3</b>–<b>13</b>) and 10 known (<b>14</b>–<b>23</b>) sesquiterpenoids were isolated from the whole plants of <i>Artemisia freyniana</i>. Their structures were elucidated by spectroscopic data analysis and comparison with published NMR data. The absolute configurations of the new isolates (<b>1</b>–<b>13</b>) were assigned based on single-crystal X-ray diffraction data and comparison of the experimental and calculated ECD data. The eremophilane derivatives <b>8</b> and <b>9</b> possess an unprecedented 2-isopropyl-3,7,7a-trimethyl-2,4,5,6,7,7a-hexahydro-1<i>H</i>-indene scaffold, and a putative biosynthetic pathway for these compounds is proposed. Compounds <b>4</b>, <b>5</b>, and <b>9</b> exhibited inhibitory effects against LPS-stimulated nitric oxide (NO) production in RAW 264.7 macrophage cells with IC<sub>50</sub> values of 10.8, 12.6, and 11.7 μM, respectively.