Dibenzocyclooctadiene lignans from Artemisia sieversiana and their anti-inflammatory activities.

Two previously undescribed dibenzocyclooctadiene lignans, named sieverlignans D-E (1-2), as well as eight known ones (3-10), were isolated from the aerial parts of Artemisia sieversiana. Their structures were elucidated from extensive spectroscopic analysis, including HRMS, NMR and electronic circular dichroism (ECD) experiments. This study is the first to report dibenzocyclooctadiene lignans in the genus Artemisia and this plant. All the compounds were evaluated for their anti-neuroinflammatory activities on the lipopolysaccharides (LPS)-induced nitric oxide production in BV-2 murine microglial cells. Compounds 1 and 6 exhibited the moderate activities with their IC50 values of 47.7 and 21.9 μM, compared to a positive control quercetin with the IC50 value of 16.0 μM.