4-Phenylcoumarins from Mesua elegans with acetylcholinesterase inhibitory activity

Nine 4-phenylcoumarins have been isolated from Mesua elegans, in which three are new; mesuagenin A, mesuagenin C, mesuagenin D, and one is a newly reported natural product; mesuagenin B. Chemical structures were elucidated using spectroscopic techniques, notably 1D and 2D NMR spectroscopy. Four compounds showed significant inhibitory activity against acetylcholinesterase, with mesuagenin B being the most potent (IC 50 = 0.7 μM). A significant acetylcholinesterase (AChE) inhibitory activity was observed for the hexane extract from the bark of Mesua elegans (Clusiaceae). Thus, the hexane extract was subjected to chemical investigation, which led to the isolation of nine 4-phenylcoumarins, in which three are new; mesuagenin A ( 1), mesuagenin C ( 3), mesuagenin D ( 4) and one new natural product; mesuagenin B ( 2). The structures of the isolated compounds were characterized by spectroscopic data interpretation, especially 1D and 2D NMR. Four compounds showed significant AChE inhibitory activity, with mesuagenin B ( 2) being the most potent (IC 50 = 0.7 μM).