Two phthalide dimers from the radix of Angelica sinensis

The phytochemical investigation of extracts from the radix of Angelica sinensis yielded a new phthalide dimer, 3,3'Z-6.7',7.6'-diligustilide (1), along with a known dimer, levistolide A (2). Their structures were established on the basis of spectral data, particularly using 1D-NMR and several 2D shift-correlated NMR pulse sequences (H-1-H-1 COSY, HSQC, HMBC and NOESY).