Abstract
Three pairs of enantiomeric phthalide dimers, including two new ones, angesicolides A (1) and B (2), and a new phthalide monomer (3), were obtained from the rhizomes of Angelica sinensis. Their structures were established through spectroscopic methods, quantum calculations, and chiral HPLC analysis. Compounds 1 and 2 were [2 + 2] and [4 + 2] cycloadducts of phthalide monomers, and their hypothetical biogenetic origin was proposed. Compounds 2, (+)-2, (-)-2, 4, (+)-4, and (-)-4 exhibited significant inhibitory activity against NO production with IC(50) values range from 1.23 to 5.55 μM.