Bioactive butylphthalide derivatives from Ligusticum chuanxiong.

Seven new butylphthalide derivatives, ligusticumolide A-G (1-7), together with two known butylphthalide derivatives (8-9) were isolated from an ethanol extract of Ligusticum chuanxiong Hort. The structures of these derivatives were elucidated from analysis of 1D/2D NMR, UV, IR and HRESIMS data. The absolute configurations of these derivatives were determined by electronic circular dichroism (ECD) calculations and Mosher's method. Ligusticumolide A (1) and ligusticumolide B (2) are enantiomers that were obtained by chiral separation. Ligusticumolide C (3) and ligusticumolide D (4) are diastereomers. All of the compounds were evaluated for their hepatoprotective activity against N-acetyl-p-aminophenol-induced HepG2 cell injury. Compounds 4, 5, and 7-9 showed more significant hepatoprotective activity than that of the positive control drug (bicyclol) at a concentration of 10 μM (p < 0.01).