Extracts of Sesbania drummondii (Rydb.) Cory seed are active in vivo in the P-388 lymphocytic leukemia system and cytotoxic in the KB assay. Systematic fractionation of S. drummondii has yielded sesbanine (1), a novel spirocyclic alkaloid based on the 2,7-naphthyridine nucleus, and drummondol (2), a