L-Hydroxy-2-methylanthraquinone

Intact plants and cell cultures of Streptocarpus dunnii (Gesneriaceae) contain several 1,2-naphthoquinones with a reversed prenyl side chain, such as that in dunnione (66) (Fig. 6.16), l-Hydroxy-2-methylanthraquinone (67) and 1-hydroxy-2-(hydroxymethyl)anthraquinone (68) were also isolated from this culture. Administration of [1-carboxy- C]<9-succinylbenzoate revealed that was incorporated into the 1-position of dunnione and the 10-position of anthraquinones. These results, together with those of feeding experiments in which lawsone (41) and its 2-prenyl ether (69) were applied, suggested that dunnione (66) was formed by a Claisen-type rearrangement at the 2-position of 2-carboxy-4-oxotetralone (COT) (43), whereas anthraquinones were formed by prenylation at the 2-position of 2-carboxy-4-oxo-tetralone (COT) (43) or l,4-dihydroxy-2-naphthoic acid (40) (Inouye and Leistner, 1988). 

Fig. 6. Biosynthesis of l-hydroxy-2-methylanthraquinone (XVII) and related naphthalene derivatives in Catalpa (Bignoniaceae).

In rare instances, 3-L-rhamnosyl derivatives of anthocyanidins occur in plant tissues.Frangulin (franguloside), an L-rhamnoside of 4,5,7-tri-hydroxy-2-methylanthraquinone, is found in Rhamrms spp. it probably has the glycosyloxy group at C-7. 

Dimethoxy-4-hydroxy-2-methylanthraquinone (6,8-dimethoxy-l-hydroxy-3-methyl-... 

Hydroxy-3,8-dimethoxy-2-methylanthraquinone, in T-10161 1 -Hydroxy-5,6-dimethoxy-2-methylanthraquinone, in T-10160 7-Hydroxy-2,8-dimethoxy-1 -methyl-4-aza-9-fluorenone, in T-30198 7-Hydroxy-3,4-dimethoxy-5-methylbenzo[/z] quinolin-2(l/7)-one, see A-10131 7-Hydroxy-2,9-dimethoxy-4-methyl-6//-dibenzo[, f/]pyran-6-one, see S-10001... 

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