Abstract
Three new naphthoquinone derivatives, 6-(1-ethoxyethyl)plumbagin (16), ethylidene-3,3′-biplumbagin (17), and ethylidene-3,6′-biplumbagin (18), were isolated, in addition to six known naphthoquinones, isozeylanone (10), 3,3′-biplumbagin (11), chitranone (12), methylene-3,3′-biplumbagin (13), 2,3-epoxyplumbagin (14), and 3,8′-biplumbagin (15), from the fruits of Diospyros maritima BLUME (Ebenaceae). The structures of the new compounds were established by spectroscopic methods. The eight naphthoquinones 11—18 were examined for ichthyotoxic activity and germination inhibitory activity. The quinones 11, 12, and 14—16 showed strong ichthyotoxic activity and the quinone 14 mild germination inhibitory activity.
