A new cardenolide glycoside from the roots of Streptocaulon juventas (lour.) merr. (Asclepiadaceae).

From remaining aqueous fraction of the roots of Streptocaulon juventas, one new cardiac glycoside named periplogenin 3-O-β-gentiobioside (1) together with six known ones (2-7) were isolated. Their relative structures were elucidated based on NMR spectroscopic analysis. Compound 1 showed moderate cytotoxicity against non-small cell lung carcinoma NCI-H460 and ovarian cancer HeLa cells. Moreover, compounds 2 and 3 exhibited remarkable cytotoxicity against NCI-H460 cell with the IC₅₀ values of 0.34 and 0.068 μM, respectively.