Two novel heterodimers, denticulatains A (1) and B (2), were isolated from the fronds of Macaranga denticulata. They possess an unprecedented stilbene–diterpene-type skeleton, which represents a unique class of prenylated stilbene. Their structures were elucidated by comprehensive analyses of extensive NMR and MS spectroscopic data. Compounds 1 and 2 exhibited inhibitory activity against acetylcholinesterase with the inhibition ratios of 22.1% and 27.5%, respectively, at a concentration of 50 μM.