Knipholone cyclooxanthrone and an anthraquinone dimer with antiplasmodial activities from the roots of Kniphofia foliosa

► We isolated a new phenylanthrone and an anthraquinone-anthrone dimer. ► The structures were assigned by NMR and MS spectroscopic techniques. ► The new compounds showed antiplasmodial activities against the W2 and D6 strains of Plasmodium falciparum.