Phytochemical investigations of ethanol root bark and stem bark extracts of (Benth.) Oliv. (Annonaceae) yielded a new benzopyranyl cadinane-type sesquiterpene (cleistonol, ) alongside 12 known compounds (-). The structures of the isolated compounds were established from NMR spectroscopic and mass spectrometric analyses. Structures of compounds and were further confirmed by single crystal X-ray crystallographic analyses, which also established their absolute stereochemical configuration. The ethanolic crude extract of root bark gave 72% inhibition against the chloroquine-sensitive 3D7-strain malaria parasite at 0.01 μg/mL. The isolated metabolites dichamanetin, ()-acetylmelodorinol, and cleistenolide showed IC = 9.3, 7.6 and 15.2 μM, respectively, against 3D7. Both the crude extract and the isolated compounds exhibited cytotoxicity against the triple-negative, aggressive breast cancer cell line, MDA-MB-231, with IC = 42.0 μg/mL (crude extract) and 9.6-30.7 μM (isolated compounds). Our findings demonstrate the potential applicability of as a source of antimalarial and anticancer agents.