Anthraquinones from the roots of Knoxia valerianoides

Five new 9,10-anthraquinones (1-5) were isolated from an ethanol extract of the roots of Knoxia valerianoides. Their structures including absolute configuration of 1 were determined by spectroscopic analysis. Compounds 4 and 5 showed moderate activity against nitrogen oxide production in macrophages induced by lipopolysaccharide, at 10(- 5) M, with inhibition ratios of 50.4 ± 3.6 and 41.7 ± 2.1%, respectively.