Dimeric furanocoumarins from the roots of Angelica dahurica.

Three new dimeric furanocoumarins, dahuribiethrins H-J (1-3), and a new ester coumarin, dahurinol A (4), were isolated from the roots of Angelica dahurica. Their structures were elucidated on the basis of extensive spectroscopic data including UV, IR, HRESIMS, 1D and 2D NMR. Compounds 2 and 3 exhibited inhibition of nitric oxide production in the lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophage cells with IC values of 8.7 ± 0.6 and 27.3 ± 0.9 μM, respectively.