Japonicones Q-T, four new dimeric sesquiterpene lactones from Inula japonica Thunb.

Four new dimeric sesquiterpene lactones (japonicones Q–T, 1–4) were isolated from the aerial part of Inula japonica Thunb., together with two known ones. Their structures were determined mainly by 1D and 2D NMR spectroscopic techniques including HSQC, 1H–H COSY, HMBC, and NOESY. Herein, the inhibitory activities against lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 macrophages of 1–6 were evaluated; IC50 values were tested as 8.5, 8.9, 4.3, 4.3, 4.2, and 9.2μM, respectively.