Phthalide mono- and dimers from the radix of Angelica sinensis

Abstract

Phytochemical investigation of the radix of Angelica sinensis has led to the isolation and identification of a new phthalide dimer, (3 Z)-(3a R,6 S,3′ R,8′ S)-3a.8′,6.3′-diligustilide ( 1), along with three known phthalide dimers, including riligustilide ( 2), levistolide A ( 3), senkyunolide O ( 4), and three known phthalide monomers, including 3,9-dihydroxyl-ligustilide ( 5), ( Z)-butylidene phthalide ( 6), ( Z)-ligustilide ( 7). Their structures were determined by spectroscopic methods including IR, NMR ( 1H NMR, 13C NMR, COSY, HSQC, HMBC and NOESY) and MS. Meanwhile, the possible biosynthesis pathways of compounds 1 and 5 were hypothesized.