Biologically Active Constituents of Arnebia euchroma: Structures of New Monoterpenylbenzoquinones: Arnebinone and Arnebifuranone.

Two quinonic compounds, arnebinone and arnebifuranone, were isolated from the roots of Arnebia euchroma and their structures were elucidated on the basis of spectral evidence. Arnebionone is a monoterpenyl-benzoquinone in which the monoterpene moiety forms a fused ring to the benzoquinone. Arnebifuranone is another monoterpenylbenzoquinone with a furan ring containing side chain which is bonded to the benzoquinone at the head carbon of C10 moiety originating from the geranyl moiety of geranylhydroquinone.