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.