A novel naphthoquinone glycoside from Rubia peregrina L.

A phytochemical study was performed on the subterranean parts (roots and rhizomes) of Rubia peregrina. The substances were isolated from chloroform, ethyl acetate, and water soluble parts of the methanolic ex- tract using several chromatographic techniques. 1-Hydroxy-2-methyl-9,10-anthraquinone (1), 1,3-dihydroxy- 2-methyl-9,10-anthraquinone (2), and 1,3-dihydroxy-2-methoxymethyl-9,10-anthraquinone (3)wereisolated from the chloroform phase; and asperuloside (4), asperulosidic acid (5), rubiadin 3-O-β -primeveroside (6), lucidin 3-O-β -primeveroside (7), deacetylasperulosidic acid (8), liriodendrin (9), and a new naphthoquinone glycoside, 2-hydroxy-3-O-β -primeveroside naphthalene-1,4-dione (inkumoside, 10), from the aqueous phase. The structures of the compounds were elucidated by means of spectral analysis (¹H-NMR, ¹³C-NMR, 2D- NMR-COSY, HMBC, HMQC-, EI-MS and ESI-MS).