New antimicrobial metabolites from the medicinal herb Artemisia herba-Alba.

Artemisia herba-alba is widely used in traditional medicines for the treatment of several diseases. From the aerial parts organic extract of A. herba-alba, two new compounds, 1,3,8-trihydroxyeudesm-4-en-7α,11ßH-12,6α-olide (1) and 5-ß-​D-​glucopyranosyloxy​-​7-methoxy-​6H-​benzopyran-​2-​one (2), respectively, together with five known metabolites: 3α,8ß-dihydroxygermacr-4(15),9(10)-dien-7ß,11αH,12,6α-olide (3), 1ß,8α-dihydroxy-11α,13-dihydrobalchanin (4), 11-epiartapshin (5), tomenin (6) and benzoic acid, p-​(ß-​D-​glucopyranosyloxy)​-​methyl ester (7), were isolated and identified. The chemical structures were proven depending upon spectroscopic analysis, including 1 D/2D NMR as and ESI-MS. Compound 1 inhibited Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus. Compounds 2 and 3 exhibited antibacterial activity against both gram-positive and gram-negative bacteria.