Bioactivity-directed fractionation led to the isolation of 19 compounds, including three oxoaporphines, oxopurpureine (5), oxonuciferine (6), and oxoglaucine (7); three aporphines, (+)-predicentrine (8), (-)-glaucine (9), and thalbaicalidine (10); one aporphine sensu stricto, N-formyl-purpureine (11); one proaporphine, glaziovine; one phenanthrene, thalicpureine (12); two 6a,7-dehydroaporphines, dehydrolirinidine (13) and 7-hydroxy-dehydroglaucine (14); four flavonoids, quercetin-3-O-rhamnoside, kaempferol-3-O-rhamnoside, isorhamnetin-3-O-rhamnoside, and tanarixetin-3-O-rhamnoside; one purine, adenine; one lactam amide, squamolone; and two steroids, beta-sitosterol and beta-sitosterol-beta-D-glucoside from the MeOH extract of the leaves of Formosan Annona purpurea. Among them, 11-14 were characterized as new compounds and alkaloids, 5-8, 10, and 12-14 exhibited significant antiplatelet aggregation activity.