Oligostilbenoids with Acetylcholinesterase Inhibitory Activity from Dipterocarpus alatus

Phytochemical investigation of the stem wood of Dipterocarpus alatus led to the isolation and characterization of four new oligostilbenoids, dipterocarpols A–D ( 1 – 4 ), together with two known resveratrol oligomers, hopeahainol ( 5 ) and hopeafuran ( 6 ). The structures of the new compounds were determined by comprehensive spectral analysis including 1D and 2D NMR, and high-resolution MS. The absolute configurations were determined by NOESY and CD spectra. Dipterocarpol A ( 1 ) and hopeahainol A ( 5 ) showed moderate acetylcholinesterase inhibitory activity with IC 50 values of 8.28 µM and 11.28 µM, respectively. Furthermore, the discovery of compound 3 gave the first evidence that the biosynthetic origin of resveratrol aneuploids is related to the loss of a half resveratrol unit by oxidative cleavage.