Anti-Inflammatory Activities of Compounds Isolated from the Rhizome of Anemarrhena asphodeloides

Abstract

Fifteen unreported compounds in <i>Anemarrhena asphodeloides</i>, iriflophene (<b>3</b>), hostaplantagineoside C (<b>7</b>), tuberoside G (<b>8</b>), spicatoside B (<b>9</b>), platycodin D (<b>14</b>), platycoside A (<b>15</b>), platycodin D2 (<b>16</b>), polygalacin D2 (<b>17</b>), platycodin D3 (<b>18</b>), isovitexin (<b>20</b>), vitexin (<b>21</b>), 3,4-dihydroxyallylbenzene-3-<i>O</i>-α-l-rhamnopyranosyl(1→6)-β-d-glucopyranoside (<b>22</b>), iryptophan (<b>24</b>), adenosine (<b>25</b>), α-d-Glucose monoallyl ether (<b>26</b>), together with eleven known compounds (<b>1</b>, <b>2</b>, <b>4</b>⁻<b>6</b>, <b>10</b>⁻<b>13</b>, <b>19</b> and <b>23</b>), were isolated from the rhizomes of <i>Anemarrhena asphodeloides</i>. The chemical structures of these compounds were characterized using HRMS and NMR. The anti-inflammatory activities of the compounds were evaluated by investigating their ability to inhibit LPS-induced NO production in N9 microglial cells. Timosaponin BIII (TBIII) and trans-hinokiresinol (<i>t</i>-HL) exhibited significant inhibitory effects on the NO production in a dose-dependent manner with IC₅₀ values of 11.91 and 39.08 μM, respectively. Immunoblotting demonstrated that TBIII and <i>t</i>-HL suppressed NO production by inhibiting the expressions of iNOS in LPS-stimulated N9 microglial cells. Further results revealed that pretreatment of N9 microglial cells with TBIII and t-HL attenuated the LPS-induced expression tumor necrosis factor (TNF)-α and interleukin-6 (IL-6) at mRNAs and protein levels. Moreover, the activation of nuclear factor-κB (NF-κB) and phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathways were inhibited by TBIII and <i>t</i>-HL, respectively. Our findings indicate that the therapeutic implication of TBIII and <i>t</i>-HL for neurogenerative disease associated with neuroinflammation.