New Resveratrol Oligomers from the Stem Bark of Hopea hainanensis

Three new resveratrol oligomers, hopeahainanphenol ( 1 ), neohopeaphenol A ( 2 ), and neoisohopeaphenol A ( 3 ), were isolated from the stem bark of Hopea hainanensis (Dipterocarpaceae). Their structures were elucidated by in‐depth spectroscopic analyses, including 1D‐ and 2D‐NMR techniques, and by HR‐ESI‐MS. All the three phytochemicals were tested in vitro for acetylcholinesterase (AChE) inhibitory and antitumor activity. The dimeric compound 2 , which corresponds to (1S*,6S*,7S*,11bS*)‐1,6,7,11b‐tetrahydro‐1,7‐bis(4‐hydroxyphenyl)‐6‐(1R*,6R*,7R*,11bR*)‐1,6,7,11b‐tetrahydro‐4,8,10‐trihydroxy‐1,7‐bis(4‐hydroxyphenyl)benzo6,7]cyclohepta1,2,3‐cd]benzofuran‐6‐yl]benzo6,7]cyclohepta1,2,3‐cd]benzofuran‐4,8,10‐triol, was found to be significantly active against AChE, with an IC₅₀ value of 7.66 ± 0.13 μm.