Two New C21 Steroidal Glycosides from the Roots of Cynanchum paniculatum

Two new C21 steroidal glycosides,paniculatumosides H and I,together with four known ones were isolated from the roots of Cynanchum paniculatum(Bge.)Kitag.Their structures were identifed by spectroscopic methods including extensive 1D and 2D NMR techniques.All compounds were subjected to detect the anti-tobacco mosaic virus(TMV)activities and their cytotoxities against three human tumor cell lines(SMMC-7721,MDA-MB-231 and A549).The results showed that compounds 1 and 5 exhibited potent protective activities against TMV,while 2,4 and 6 had moderate efects on the SMMC7721 cancer cells viability.