Alkaloids from the Branches and Leaves of Elaeocarpus angustifolius

Nine new alkaloids, (+)-1, (−)-1, 2, (+)-3, (−)-3, and 4–7, along with five known compounds (8–12), were obtained from the branches and leaves of Elaeocarpus angustifolius. The alkaloids were structurally characterized by NMR and MS data. The absolute configurations of (+)-1, (−)-1, (+)-3, and (−)-3 were determined by comparing their experimental and computed electronic circular dichroism spectra. (±)-8,9-Dehydroelaeocarpine (5), (±)-9-epielaeocarpine cis-N-oxide trifluoroacetate (6), and (±)-elaeocarpine trifluoroacetate (9) exerted weak inhibitory activities against butyrylcholinesterase with IC₅₀ values of 39, 29, and 35 μM, respectively, while that of tacrine, the positive control, was 0.07 ± 0.01 μM. This is the first report of the cholinesterase inhibitory activities of Elaeocarpus alkaloids.