Two New Biflavonoids from the Roots and Rhizomes of Sinopodophyllum emodi

Two new biflavonoids, sinodiflavonoids A ( 1 ) and B ( 2 ), were isolated from the roots and rhizomes of Sinopodophyllum emodi. Their structures were established on the basis of extensive spectroscopic evidences (HR-ESI-MS, 1 H NMR, 13 C NMR, HSQC, HMBC, CD). Their cytotoxic activities were evaluated in comparison with etoposide against four cell lines (MCF-7, HepG2, HeLa, KB). The preliminary structure–activity relationships showed that the simple, nonprenylated, nonmethylated biflavonoid ( 2 ) showed higher cytotoxic activities than the corresponding prenylated 3-hydroxymethylated one ( 1 ).