A new cycloartane glucoside from Rhizophora stylosa.

Nine secondary metabolites, including a new cycloartane glucoside, rhizostyloside (1), were isolated from a methanol extract of Rhizophora stylosa leaves through several chromatographic experiments. The structures of the compounds were determined on the basis of NMR spectroscopic (1H and 13C NMR, HSQC, HMBC, 1H-1H COSY, NOESY) and HR-ESI-MS data and by comparison with literature values. Compound 1 exhibited significant cytotoxicity against three human cancer cell lines: KB (epidermoid carcinoma), LU-1 (lung adenocarcinoma), and SK-Mel-2 (melanoma). In addition, 1 strongly activated caspase-3/7 in LU-1 cells.