Isolation and cytotoxic effect of anthraquinones from Morinda umbellata.

Four new anthraquinones, 1,6-dihydroxy-2-methoxymethylanthraquinone (1), 6-hydroxy-7-methoxy-2-methoxymethylanthraquinone (3), 3,6-dihydroxy-7-methoxy-2-methylanthraquinone (4), and 6-hydroxy-2-methoxymethylanthraquinone (8), together with 12 known anthraquinones and 6 other known compounds, were isolated from the EtOAc extract of Morinda umbellata. Among the isolated compounds, 1, rubiadin (14), and, 3-hydroxy-2-hydroxymethylanthraquinone (16) exhibited significant cytotoxicities against HepG2 cells, with GI50 values of 4.4, 3.6, and 4.8 µM, respectively. Georg Thieme Verlag KG Stuttgart · New York.