RESUMEN
The root of Cynanchum auriculatum (C. auriculatum) Royle ex Wight has been shown to possess various pharmacological effects and has recently attracted much attention with respect to its potential role in antitumor activity. The C-21 steroidal glycosides are commonly accepted as the major active ingredients of C. auriculatum. In this study, the antitumor abilities of different extracted fractions of the root bark and the root tuber of C. auriculatum were investigated by using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay in human cancer cell lines HepG2 and SMMC-7721. The results showed that the chloroform and ethyl acetate fractions of the root tuber suppressed tumor cell growth strongly. To identify and characterize the chemical constituents of different active fractions, an ultra high performance liquid chromatography with triple-quadrupole tandem mass spectrometry method was developed for the simultaneous quantitation of eight C-21 steroidal glycosides. The analysis revealed that the C-21 steroidal glycosides were concentrated in the chloroform and ethyl acetate fractions, and the total contents of different fractions in the root tuber were significantly higher than those of corresponding ones in the root bark. Furthermore, the C-21 steroidal glycosides based on different types of aglucones were prone in different medicinal parts of C. auriculatum.