Cytotoxic phenyl polyketides from Hypericum curvisepalum N. Robson

Abstract

±)-Hypecurvone A (1) and B (2), two pairs of undescribed phenyl polyketides, along with seven known structurally related compounds 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. The structures and absolute configurations of these compounds were elucidated by extensive spectroscopic analyses and comparing the experimental and calculated ECD spectra. The cytotoxic effects of all the isolates on two human tumour cell lines (SMMC-7721 and MGC-803) were evaluated by CCK8 assay. All tested compounds exhibited moderate cytotoxicity against SMMC-7721 cells, and compound 3 also showed weak cytotoxicity toward MGC-803 cells. Because of their better activities, compounds 5-8 were selected to investigate the action mechanism of cytotoxicity on SMMC-7721 cells. Results suggested that the four compounds manifested cytotoxic activity by leading to mitochondria-mediated apoptosis and of inhibiting the G2/M phase to affected their normal growth.