Structurally Diverse Diterpenoids from the Roots of <i>Salvia deserta</i> Based on Nine Different Skeletal Types

Abstract

Twenty-four diterpenoids (<b>1</b>-<b>24</b>), classified into nine diverse carbon skeletal types, 8-<i>nor</i>-7(8→14),9(8→7)-di-<i>abeo</i>-abietane (<b>1</b>, <b>2</b>, and <b>13</b>), 7(8→14),9(8→7)-di-<i>abeo</i>-abietane (<b>3</b> and <b>4</b>), 6-<i>nor</i>-6,7-<i>seco</i>-abietane (<b>5</b> and <b>6</b>), 6,7-<i>seco</i>-abietane (<b>7</b> and <b>11</b>), 9,10-<i>seco</i>-abietane (<b>8</b>), abietane (<b>9</b>, <b>10</b>, and <b>14</b>-<b>21</b>), 11(9→8),20(10→11)-di-<i>abeo</i>-abietane (<b>12</b>), 15(13→12)-<i>abeo</i>-abietane (<b>22</b> and <b>23</b>), and 4,5-<i>seco</i>-20(10→5)-<i>abeo</i>-abietane (<b>24</b>), respectively, were isolated from the roots of <i>Salvia deserta</i>. The structures of 10 new diterpenoids, named salviadesertins A-J (<b>1</b>-<b>10</b>), were elucidated by spectroscopic data interpretation, quantum-chemical calculations including calculated ¹³C NMR-DP4+ analysis and electronic circular dichroism as well as X-ray crystallography analysis. The absolute configurations of compounds <b>1</b>-<b>3</b>, <b>7</b>, <b>14</b>, and <b>22</b> were defined by single-crystal X-ray diffraction analysis. All the isolated diterpenoids <b>1</b>-<b>24</b> were evaluated for their cytotoxicity against five cancer cell lines, and 6-hydroxysalvinolone (<b>14</b>) showed micromolar potencies against MCF-7, A-549, SMMC-7721, and HL-60 cells, whereas the other diterpenoids were inactive (half-maximal inhibitory concentration greater than 10.0 μM).