Apoptosis-inducing effect of akebia saponin D from the roots of Dipsacus asper Wall in U937 cells.

Methanol extracts of the root of Dipsacus asper Wall (Dipsacaceae) were found to exhibit apoptosis-inducing activities in U937 (human monocyte-like histiocytic) cells. Investigation of the active n-BuOH fraction led to the isolation of akebia saponin D (ASD). Structure was established by spectroscopic methods. Treatment of U937 cells with ASD induced apoptosis in a dose dependent manner. ASD exerted strong cytotoxicity against human and murine leukemia cells. It is significantly increased the subG1 cell population and expression of p53 and Bax gene. And also ASD enhanced NO production from RAW264.7 macrophage cells. Taken together, these results strongly indicate that ASD may exert apoptosis-inducing activity via induction of apoptosis through activation chiefly via the nitric oxide and apoptosis-related p53 and Bax gene expression. These data provide scientific evidence that Dipsacus asper Wall can be useful as a chemopreventive agent.