Ebenaceae extractives. Part III. Binaphthaquinones from Diospyros species

Abstract

Diospyrin and isodiospyrin have been isolated from the bark of Diospyros mespiliformis. Isodiospyrin was also found in the bark and wood of D. virginiana. Isodiospyrin is optically active and, like diospyrin, is an unsymmetrical dimer of 7-methyljuglone, the two naphthaquinone moieties being coupled at C-6 and C-8′. The bark of D. elliptifolia contains betulin, lupeol, plumbagin (2-methyljuglone), and another dimer, elliptinone, which is isomeric with diospyrin and isodiospyrin. Elliptinone has the structure 6,6′-biplumbagin.