Thirteen naphthoquinone derivatives (1-13)(Table 2) have been isolated from the roots of Diospyros spp. and Maba buxifolia (Ebenaceae)(Table 3) and the structures of the compounds (1-4, 7-13) were determined. The linking positions of the two naphthoquinone units in isodiospyrin (11) was clarified by the determination of nuclear Overhauser effects. The structure of bisisodiospyrin (10), a novel tetrameric naphthoquinone, was elucidated from spectroscopic methods. The structure of shinanolone (3), a tetralone derivative, was established by the physical methods and the correlation with 7-methyljuglone (6). The absolute configurations of these compounds were also discussed.
