Cytotoxicity of Secondary Metabolites from Dracaena viridiflora Engl & Krause and their Semisynthetic Analogues

The MeOH extract of Dracaena viridiflora was found to display significant cytotoxicity against some cancer cell lines. Systematic phytochemical investigation of this extract led to the isolation and structure elucidation of ten secondary metabolites including five spirostane (1-5) and one furostane (6) steroidal saponins. Furthermore, some acetylated spirostane analogues and three previously unreported derivatives with the 22,26epoxycholesta-5,22-diene skeleton (15-17) were prepared from trillin (1), prosapogenin A of dioscin (2) and dioscin (4) by reaction with ZnCl2/Ac2O. Among the isolated and semisynthetic compounds, dioscin showed the most potent cytotoxicity against A549, Jurkat and Skov-3 cells with IC50 values of 0.42, 1.70 and 1.90 μg/mL, respectively. It was noteworthy that acetylation of the bioactive compounds led to semisynthetic derivatives which unfortunately did not present any activity. This is the first report on the phytochemical and pharmacological investigation of Dracaena viridiflora.