Prenylated flavonoids from the fruits of Sinopodophyllum emodi and their cytotoxic activities

Thirteen new prenylated flavonoids, sinoflavonoids C–O (1–13), were isolated from the fruits of Sinopodophyllum emodi together with eleven known analogues (14–24). Their structures were elucidated on the basis of spectroscopic evidence. The cytotoxic activities of all isolated compounds were evaluated against MCF-7 and HepG2 cell lines. By the preliminary structure–activity relationships, it was first discovered that the simple, non-prenylated 5,7,3′,4′-tetrahydroxyflavonol analogues (22 and 23) showed higher cytotoxic activities than the corresponding prenylated ones (1–2, 4–21, and 3 and 24). Compound 22 exhibited the most potent cytotoxicity against MCF-7 and HepG2 cell lines with IC50 values of 3.14 and 2.08 μM, respectively.