Fractionation and chromatography of an ethanol extract of the stembark of Guatteria melosma Diels (Annonaceae) afforded the new noraporphine alkaloid, 3-hydroxynornuciferine (1) and its corresponding oxoaporphine alkaloid, isomoschatoline (2). The latter alkaloid was also isolated from an ethanol extract of the stembark of Cleistopholis patens Engl. & Diels (Anonaceae). The structure of 3-hydroxynornuciferine (1,2-dimethoxy-3-hydroxynoraporphine) (1) was confirmed by a consideration of its spectral data and that obtained on its N,O-diacetyl (5) and N-methyl (6) derivatives. The latter derivative was identical (ir, 1H-nmr, ma, [α] d) to 3-hydroxynuciferine (6). A consideration of the spectral data of isomoschatoline (2), its O-methyl (8) and O-acetyl (9) derivatives indicated that the alkaloid was 1,2-dimethoxy-3-hydroxyoxoaporphine. Reduction and subsequent acetylation of the alkaloid afforded a product that was identical (ir, 1H-nmr, ms) to N,O-diacetyl-3-hydroxynornuciferine (5). In addition, the morphinandienone alkaloid, pallidine (3) was isolated from G. melosma; the oxoaporphine alkaloid, liriodenine (4) was isolated from both G. melosma and C. patens; and an uncharacterized alkaloid, CPA 1, was isolated from C. patens. © 1982, American Chemical Society. All rights reserved.