Studies on the alkaloids of papaveraceous plants. XXV. Biosynthesis of the alkaloids of Corydalis incisa Pers, and Chelidonium majus L. Incorporations of tetrahydroprotoberberines, N-methosalts of tetrahydroprotoberberines, and protopine.

Since dl-cheilanthifoline (2) was converted in Corydalis incisa plants into corynoline (3) and protopine (4), it was shown that 2 was the intermediate between scoulerine (15) and stylopine (10). Corycavine (9) was shown to be biosynthesized in Corydalis incisa plants from dl-mesotetrahydrocorysamine (7) and dl-tetrahydrocorysamine (8) via their α-N-methosalts (7α and 8α). Protopine (4) is shown to be formed in vivo from the α-N-methosalt of dl- or l-stylopine (10α). Incorporation of the β-N-methosalts (10β and 8β) into 4 and 9 might be absent or negligible. These results imply that α-N-methosalts of tetrahydroprotoberberines are stereospecifically converted into protopine-type alkaloids. Sanguinarine (13) and chelidonine (14) were shown to be biosynthesized in Chelidonium majus plants from α-N-methosalt of dl- or l-stylopine (10α) via protopine (4). This shows that protopine-type alkaloid is the intermediate between tetrahydroprotoberberine-type and benzo [c] phenanthridine-type alkaloids.