Armenin and isoarmenin--two prenylated coumarins from the aerial parts of Artemisia armeniaca.

The reversed-phase (RP) preparative HPLC analyses of the MeOH extract of the aerial parts of Artemisia armeniaca yielded four prenylated coumarins, 7-hydroxy-8-(4-hydroxy-3-methylbutoxy)coumarin (named armenin), 8-hydroxy-7-(4-hydroxy-3-methylbutoxy)coumarin (named isoarmenin), lacarol, and deoxylacarol, together with five other compounds, including three flavonoid glycosides, quercetin 3-O-β-D-glucopyranoside, rutin, and kaempferol 3-O-β-D-glucopyranoside, and chlorogenic acid, and tryptophan. (10E,12Z)-9-Hydroxyoctadeca-10,12-dienoic acid (β-dimorphecolic acid) was isolated from the CH(2)Cl(2) extract. Armenin and isoarmenin were new coumarins. Structures of all compounds were determined by spectroscopic means, including UV, MS, 1D- and 2D-NMR. The in vitro free-radical-scavenging property of the extracts and isolated compounds was evaluated by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) assay.