Bioactive naphthoquinone derivatives from Diospyros maritima BLUME

From the fresh fruits of Diospyros maritima BLUME (Ebenaceae) three new naphthoquinones, 3-bromoplumbagin (1), ethylidene-6,6'-biplumbagin (2), and 3-(2-hydroxyethyl)plumbagin (3), were isolated, in addition to six known naphthoquinones, 3-chloroplumbagin (4), 3-methylplumbagin (5), plumbagin (6), droserone (7), elliptinone (8), and maritinone (9). The structures of the new compounds were established by chemical acid spectroscopic means. The 21 compounds isolated from this plant were examined for ichthyotoxic activity, germination inhibitory activity, and antifungal activity. The naphthoquinone derivatives from the fruits of Diospyros maritima showed a variety of biological activities, especially plumbagin (6), which showed strong activity in these three bioassays.