Diverse neolignans and lignans from an aqueous extract of the Angelica sinensis root head

Neolignans and lignans with diverse new chemical structures, including eleven pairs of separated chiral enantiomers [(+)-/(−)-1–(+)-/(−)-5, (+)-/(−)-8, (+)-/(−)-10, and (+)-/(−)-12–(+)-/(−)-15], two achiral compounds (6 and 9), and an unseparated racemate [(±)-11], together with a new natural product (7) and 21 known derivatives, were isolated from an aqueous extract of the Angelica sinensis root head (guitou). Among the chiral isolates, (+)-/(−)-13 and (+)-/(−)-15 were scalemic pairs with enantiomeric ratios of around 3:1 and 1.5:1, respectively, while others were enantiomeric equivalent pairs. This indicates that the diverse neolignans in A. sinensis are biosynthesized via different pathways with varying degrees of stereo-controlled manners.