Structure Elucidation and Cholinesterase Inhibition Activity of Two New Minor Amaryllidaceae Alkaloids.

Two new minor Amaryllidaceae alkaloids were isolated from Hippeastrum × hybridum cv. Ferrari and Narcissus pseudonarcissus cv. Carlton. The chemical structures were identified by various spectroscopic (one- and two-dimensional (1D and 2D) NMR, circular dichroism (CD), high-resolution mass spectrometry (HRMS) and by comparison with literature data of similar compounds. Both isolated alkaloids were screened for their human acetylcholinesterase ( h AChE) and butyrylcholinesterase ( h BuChE) inhibition activity. One of the new compounds, a heterodimer alkaloid of narcikachnine-type, named narciabduliine ( 2 ), showed balanced inhibition potency for both studied enzymes, with IC ₅₀ values of 3.29 ± 0.73 µM for h AChE and 3.44 ± 0.02 µM for h BuChE. The accommodation of 2 into the active sites of respective enzymes was predicted using molecular modeling simulation.