New coumarins from the roots of Angelica dahurica var. formosana cv. Chuanbaizhi and their inhibition on NO production in LPS-activated RAW264.7 cells.

A new linear pyranocoumarin named (-)-hydroxydecursinol (1) and a new biscoumarin named (±)-dahuribiscoumarin (2), together with six known compounds isoimperatorin (3), imperatorin (4), phellopterin (5), isodemethylfuropinarine (6), demethylfuropinarine (7), and (+)-decursinol (8) were isolated from the 75% ethanolic extract of the roots of Angelica dahurica var. formosana cv. Chuanbaizhi. Their structures were elucidated by extensive spectroscopic techniques, including 2D NMR spectroscopy and mass spectrometry, and the structure of 2 was confirmed by single-crystal X-ray diffraction. All of the isolated compounds were evaluated for the inhibition against nitric oxide (NO) production in the lipopolysaccharide (LPS)-activated RAW264.7 macrophage cell line, and exhibited the inhibitory activity on NO production in a concentration-dependent manner. Furthermore, real-time PCR analysis revealed that compounds 2, 5-8 could significantly suppress the expression levels of inducible nitric oxide synthase mRNA in a concentration-dependent manner. And their primary structure-activity relationships of NO inhibitory effects were also briefly discussed. These compounds are potential candidates for further bioassay studies to determine their suitability as drug leads.