Structure determination of two new C<sub>21</sub> steroidal glycosides from <i>Cynanchum komarovii</i>

<p>Two new 13,14:14,15-disecopregnane-type C<sub>21</sub> steroidal glycosides, namely komarosides R (<b>1</b>) and S (<b>2</b>), along with four known compounds (<b>3</b>–<b>6</b>), were obtained from the 95% ethanol extract of the whole herbs of <i>Cynanchum komarovii</i> Al.Iljinski (Asclepiadaceae). The structures of new compounds were elucidated on the basis of 1D, 2D NMR spectroscopic data and acid hydrolysis. Compounds <b>1</b> and <b>2</b> showed potent inhibitory activities against human leukemia cell line (HL-60) with IC<sub>50</sub> values being 6.2 and 17.6 μM, respectively, compared to the positive control 5-fluorouracil (6.4 μM).</p>