The furano norclerodane diterpenoid disobulbin-D induces apoptosis in normal human liver L-02 cells

Disobulbin-D (DBD), a hepatotoxic furano norclerodane diterpenoid, was isolated by bio-guided fractionation from the rhizome of Dioscorea bulbifera L. In working toward elucidating the cellular and molecular mechanisms of DBD toxicity, we treated normal human liver cell line L-02 cells with DBD in vitro and evaluated its toxicity in terms of cell viability, morphologic changes, induction of Apoptosis/necrosis, and Caspase 3 activity. The viability of L-02 cells was inhibited by DBD in a concentration and time-dependent manner. Apoptosis was supported by the Annexin V and propidium iodide assay, Hoechst 33258 staining, and the occurrence of a sub-G(1) peak. DBD can cause an increase in Caspase 3 activity, and pretreatment with Ac-DEVD-CHO blocked cell death and attenuated the Apoptosis, showing that DBD-induced L-02 cell Apoptosis is Caspase 3-dependent. These results suggest that the effects of DBD on the growth of normal human liver L-02 cells may be due to its induction of cell Apoptosis, which may also explain the toxicity observed in the Plants containing furano clerodane Diterpenoids.