Cytotoxic phenyl polyketides from Hypericum curvisepalum N. Robson.

(±)-Hypecurvone A ( 1) and B ( 2) , two new undescribed phenyl polyketides, along with seven known analogues ( 3 - 9 ) were isolated from the whole plant of Hypericum curvisepalum . Chiral separation of 1 and 2 yielded two pairs of enantiomers 1a / 1b and 2a / 2b , respectively. The structures of these compounds were elucidated by extensive spectroscopic analyses and ECD spectra simulations. All isolates exhibited moderate cytotoxicity against human hepatocellular carcinoma SMMC-7721 cells, and compound 3 also showed weak cytotoxicity toward MGC-803 cells. The cytotoxicity of these compounds was found to be related to enhanced mitochondria-mediated apoptosis and inhibition of the G2/M phase of the cell cycle.