Anthraquinones with quinone reductase-inducing activity and Benzophenones from Morinda citrifolia (Noni) roots

Two new benzophenones, morintrifolins A (1) and B (2), together with 14 known anthraquinones and four other known compounds, were isolated from a chloroform-soluble extract of Morinda citrifolia roots. Of the isolated compounds, four known anthraquinones, namely, 1,2-dihydroxyanthraquinone (3), 1,3-dihydroxy-2-methylanthraquinone (4), 2-hydroxy-3-(hydroxy methyl)anthraquinone (5), and 1,3,6-trihydroxy-2-methylanthraquinone (6), exhibited quinone reductase (QR)-inducing activity in Hepa lclc7 cells, with concentrations required to double QR activity of 12.0, 8.1, 0.94, and 0.56 mu M, respectively.