Dibenzocyclooctadiene Lignans from Artemisia sieversiana and Their Nitric Oxide Inhibitory Effects

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 circular dichroism 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 effects on the lipopolysaccharides (LPS)-induced nitric oxide production in BV-2 murine microglial cells. Compounds 1 and 6 exhibited the moderate activity with their IC 50 values of 47.7 and 21.9 μ M, compared to a positive control quercetin with the IC 50 value of 16.0 μ M.