J. Koyama

Anthraquinones of Galium spurium

Abstract Constituents of Galium spurium var. echinospermon were examined and the new anthraquinones, 8-hydroxy-3-methoxy-7-methyl-1,2-methylenedioxy-9,10-anthraquinone and 2,8-dihydroxy-1,3-dimethoxy-7-methyl-9,10-anthraquinone, were isolated along with known anthraquinones. The structures of the new compounds were determined on the basis of spectroscopic data.

Two naphthoquinones from Rubia cordifolia

Abstract The methanol extract of Rubia cordifolia afforded two new naphthoquinones, 2-carbamoyl-3-methoxy-1,4- naphthoquinone and 2-carbamoyl-3-hydroxy-1,4-naphthoquinone, isolated along with a known naphthoquinone and naphthohydroquinone and six known anthraquinones. The structures of the new compounds were determined on the basis of spectroscopic data and direct comparisons with synthetic compounds.

Anthraquinones of Damnacanthus indicus

Abstract A new anthraquinone, 5-hydroxy-1,2-methylenedioxyanthraquinone, along with three known anthraquinones, damnacanthal, juzunol, and damnacanthol, and four artificial anthraquinones were isolated from the rhizomes of Damnacanthus indicus grown in Japan. The new anthraquinone was characterized as 5-hydroxy-1,2-methylenedioxyanthraquinone by comparison its methyl ether with synthetic 5-methoxy-1,2-methylenedioxyanthraquinone.