Three new naphthoquinone derivatives from Diospyros maritima BLUME

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 ne 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.