Natural cholinesterase inhibitors from Myristica cinnamomea king / Siti Mariam Abdul Wahab

A new acylphenol, malabaricone E (72) together with the known malabaricones A-C (1- 3), maingayones A and B (4 and 5) and maingayic acid B (69) were isolated from the ethyl acetate extract of the fruits of Myristica cinnamomea King. Their structures were determined by 1D and 2D NMR techniques and LCMS-IT-TOF analysis. Compounds 2 (1.84 ± 0.19 and 1.76 ± 0.21 μM, respectively) and 3 (1.94 ± 0.27 and 2.80 ± 0.49 μM, respectively) were identified as dual inhibitors, with almost equal acetylcholinesterase enzyme (AChE) and butyrylcholinesterase enzyme (BChE) inhibiting potentials. The Lineweaver-Burk plots of compounds 2 and 3 indicated that they were mixed-mode inhibitors. Based on the molecular docking studies, compounds 2 and 3 interacted with the peripheral anionic site (PAS), the catalytic triad and the oxyanion hole of the AChE. As for the BChE, while compound 2 interacted with the PAS, the catalytic triad and the oxyanion hole, compound 3 only interacted with the catalytic triad and the oxyanion hole.