New anthraquinone dimer from the root bark of Cassia artemisioides (Gaudich. Ex. DC) Randell

The phytochemical investigation of the root bark of Cassia artemisioides (Gaudich. Ex. DC) Randell resulted in the isolation of one new anthraquinone 1,1'-dihydroxy-3,3'-dimethyl-8,8'-dimethoxy-6,6'-O-bianthraquinone (1) along with four known anthraquinones 1,6-dihydroxy-8-methoxy-3-methylanthraquinone (2), 1-hydroxy-8-methoxy-3-methylanthraquinone (3), 1,8-dihydroxy-6-methoxy-3-methylanthraquinone (4), and 1,6,8-trihydroxy-3-methylanthraquinone (5). The structures of the compounds were elucidated using spectroscopic techniques including 1D and 2D NMR. The compounds were evaluated for antioxidant activity. 1,6,8-Trihydroxy-3-methyl anthraquinone (5) showed good activity among the tested compounds.