Two new isoquinoline alkaloids from the seeds of Nandina domestica.

Two new isoquinoline alkaloids, 6 R,6aS-N-nantenine N_β-oxide (1), 6S,6aS-N-nantenine N_α-oxide (2), along with nine known alkaloids, nantenine (3), oxonantenine (4), protopine (5), nornantenine (6), N-methyl-laurotetanine (7), isocorydine (8), O-methyflavinantine (9), N-methyl-2,3,6-trimethoxymorphinan-dien-7-one N_β-oxide (10) and (+)-10-O-methylhernovine N_β-oxide (11) were isolated from the seeds of Nandina domestica. Their structures were elucidated by extensive analyses of spectroscopic data (IR, UV, HRESIMS, 1 D and 2 D NMR), ECD calculation and comparison with the related literatures. In addition, the cytotoxicity against A549 cells of these alkaloids was determined by the MTT assay.