Catharanthus alkaloids, XXXVIII. Confirming structural evidence and antineoplastic activity of the bisindole alkaloids leurosine-N'b-oxide (pleurosine), roseadine and vindolicine from Catharanthus roseus.

Additional and confirming chemical and spectroscopic evidence for vindolicine (4), roseadine (5), and leurosine-N'b-oxide (6) is presented. Leurosine-N'b-oxide (6) was found to be exceptionally active in the B-16 melanoma test system in vivo. Roseadine (5), a new isolate of Catharanthus roseus, and 6 displayed significant activity in the P-388 lymphocytic leukemia test system in vivo. Preliminary spectral studies on the new alkaloid roseamine are also described.