Chemical constituents with potential cytotoxic activities from Cynanchum otophyllum

Phytochemical investigation of the chloroform extract of the roots of Cynanchum otophyllum (Asclepiadaceae) led to the isolation of a new cardiac aglycone, characterised as Cynanchin A (1), as well as one known cardenolide (2) and nine known C21 steroidal glycosides (3-10), Their structures were established by 1D and 2D NMR spectra referring to the literature, together with high-resolution mass spectrometric analysis. In the present research, the cytotoxic activities of the 11 compounds on five different human cancer cell lines (HL-60, SMMC-7721, A-549, MCF-7 and SW480) were evaluated in vitro. Most of the tested compounds showed potent inhibitory activities towards the five cell lines.