Five new biflavonoids with acetylcholinesterase inhibitory activity from Diphylleia sinensis

Abstract

Five new biflavonoids, diphybiflavonoids A − E (1–5), were isolated from the roots and rhizomes of Diphylleia sinensis. Their structures were elucidated by extensive spectroscopic data, including UV, IR, HR-ESI-MS and 2D NMR. Their absolute configurations were determined by ECD spectra. All isolated compounds were evaluated for acetylcholinesterase (AChE) inhibitory activity. Compounds 1–4 exhibited the potent AChE inhibitory activities with IC50 values of 1.62, 2.10, 2.08, and 5.15 μM, respectively. The preliminary structure-activity relationship study indicated that the connection mode (C2-O-C4′′′/C3-O-C3′′′ or C2-O-C3′′′/C3-O-C4′′′) of biflavonoid subunits, and 3-hydroxy group of flavonol subunit were important structural factors for AChE inhibitory activity. Biflavonoids, containing a C2-O-C4′′′/C3-O-C3′′′ or C2-O-C3′′′/C3-O-C4′′′ linkage, can be a potentially useful platform for development of cholinesterase inhibitors.