Duguevalline (1), a novel aporphinoid alkaloid, in addition to four known alkaloids, cleistopholine (2), O-methylmoschatoline (3), (-)-oliveroline (4) and (-)-oliveridine (5), were isolated and characterized from Duguetia vallicola stems. Structural elucidation of these compounds was established by spectroscopic methods. Among them, alkaloids (2) and (4) exhibited antiplasmodial activity against Plasmodium falciparum.