Four new honokiol derivatives from the stem bark of Magnolia officinalis and their anticholinesterase activities

Abstract

Four new honokiol derivatives, namely 8′,9′-dihydroxymagnaldehyde E (1), 8′,9′-dihydroxyhonokiol (2), erythro-7-O-methylhonokitriol (3), and threo-7-O-methylhonokitriol (4), together with seven known compounds, erythro-honokitriol (5), threo-honokitriol (6), magnaldehyde E (7), magnotriol B (8), magnaldehyde B (9), honokiol (10), and magnolol (11), were isolated from the stem bark of Magnolia officinalis. Their structures were established on the basis of extensive 1D and 2D NMR experiments as well as HR-MS. All isolates were evaluated for their in vitro activities against acetylcholinesterase and butyrylcholinesterase, the results demonstrated that compound 8 possessed potent inhibitory activity.