The cytotoxicity of the isolated compounds was evaluated
by the MTT method. As showed in Table 1, the prenylated
flavonoids exhibited strong cytotoxic effects against three
cancer cell lines while kaempferol showed a weak effect. This
indicated that the prenyl or geranyl group as well as their
cyclization with the hydroxy group increased the cytotoxicity
of flavone. Morusin (9) was the most potent against the HeLa
cell linewith an IC50 value of 0.64 μM. This effect was significant
in comparison with an antitumor agent, deguelin. It has
reported that morusin at 29 μM induced apoptosis of human
colorectal cancer HT-29 cells by activating caspase-3, 8 and 9
proteins and inhibiting nuclear factor κB signaling [18]. Thus
the potent cytotoxic effect of morusin against HeLa cells in the
present study could be due to similar mechanisms. Further