Morphinan and isoquinoline alkaloids from the tuberous roots of <i>Stephania cepharantha</i>

A new morphinan alkaloid (6S, 9S, 13 R, 14S)-6-O-acetyl-7,8-Didehydro-4-hydroxy-3,7-dimethoxymorphinan-6-ol (1), and a new naturally occurring cularine alkaloid (S)-2, 3, 12, 12a-tetrahydro-5, 6, 9, 10-tetramethoxy-1-methyl-1H-[1]benzoxepino[2, 3, 4-ij]isoquinoline(5), along with four known alkaloids were isolated from the roots of Stephania cepharantha. The structures of these compounds were elucidated based on spectroscopic data analyses. Cytotoxic activities of the compounds against three human cancer cell lines (A549, MCF-7 and SW480) were also evaluated.