Dimeric guaianolides from Artemisia absinthium

Five dimeric guaianolides, absinthins A-E, and seven known dimeric guaianolides were isolated from Artemisia absinthium. Their structures were elucidated based on 1D- and 2D-NMR experiments, including (1)H NMR, (13)C NMR, DEPT, (1)H-(1)H COSY, HSQC, HMBC, and NOESY, and through HRESIMS data analysis. The absolute configuration of the known compound, anabsinthin, was determined by X-ray crystallographic analysis. The isolated compounds were tested to assess their inhibitory activities on lipopolysaccharide (LPS)-induced nitric oxide (NO) production in BV-2 cells; absinthin C and isoanabsinthin exhibited significant inhibitory effects with IC50 values of 1.52 and 1.98μM, respectively.