New tetrahydroprotoberberine N-oxide alkaloids and cytotoxic constituents of Corydalis tashiroi

Three new tetrahydroprotoberberine N-oxide alkaloids, (-)-cis-corydalmine N -oxide (1), (-)-trans-corydalmine N-oxide (2), and (-)-trans-isocorypalmine N-oxide (3), along with three known benzo[c]phenanthridine alkaloids, nors anguinarine (4), dihydrosanguinarine (5), and oxysanguinarine (6), six know n berberine alkaloids, (-)-tetrahydropalmatine (7), (-)-corydalmine (8), (- )-scoulerine (9), (-)-corynoxidine (10), (-)epicorynoxidine (11), palmatine (12), and protopine (13), have been isolated from the herb Corydalis tashi roi. The structures of these compounds were elucidated by spectroscopic ana lysis. Three of the isolated compounds show significant cytotoxic activitie s (ED50 values < 4 mu g/ml) against P-388, KB16, A549, and HT-29 cell lines .