Chemical Constituents from the Roots and Rhizomes of Asarum heterotropoides var. mandshuricum and the In Vitro Anti-Inflammatory Activity

Abstract

Anti-inflammatory compounds were investigated from the ethanol extract of the roots and rhizomes of <i>Asarum heterotropoides</i> var. <i>mandshuricum</i>, a traditional Chinese medicine called Xixin and used for pain and inflammatory. Nine new compounds were isolated, including six new lignans, neoasarinin A-C (<b>1</b>-<b>3</b>), neoasarininoside A and B (<b>4</b> and <b>5</b>), and asarinin B (<b>7</b>), and one new monoterpene, asarincin A (<b>8</b>), two new amides, asaramid II and III (<b>10</b> and <b>11</b>), and one new natural monoterpene, asaricin B (<b>9</b>), along with 37 known compounds (<b>6</b>, <b>12</b>-<b>47</b>). Their structures and absolute configurations were elucidated on the basis of spectroscopic methods and chemical analyses. This is the first report of the absolute configuration of asarinin A (<b>6</b>). The 8-<i>O</i>-4' neolignans (<b>1</b>-<b>5</b>) were reported in the genus <i>Asarum</i> for the first time. The 15 compounds <b>17</b>, <b>19</b>, <b>22</b>-<b>25</b>, <b>28</b>, <b>31</b>, <b>36</b>, <b>40</b>, <b>42</b>, <b>43</b>, <b>45</b>-<b>47</b> were isolated from the genus <i>Asarum</i>, and compounds <b>16</b>, <b>32</b>, <b>33</b>, <b>37</b> and <b>39</b> were isolated from <i>A. heterotropoides</i> var. <i>mandshuricum</i> for the first time. Thirty-seven of the isolates were evaluated for anti-inflammatory activity against the release of β-glucuronidase in polymorphonuclear leukocytes (PMNs) induced by the platelet-activating factor (PAF), and compounds <b>1</b>, <b>4</b>, <b>7</b>, <b>8</b>, <b>14</b>, <b>17</b>-<b>19</b>, <b>22</b>, <b>24</b>, <b>25</b>, <b>29</b>, <b>30</b>, <b>32</b>, <b>33</b>, <b>40</b>-<b>43</b>, <b>45</b>, and <b>46</b> showed potent anti-inflammatory activities in vitro, with 27.9%-72.6% inhibitions at 10^-5 mol/L. The results of anti-inflammatory assay suggested that lignans obtained from the CHCl₃ extract might be the main active components of Xixin.