Aromatic acid derivatives from the lateral roots of Aconitum carmichaelii

Seven new aromatic acid derivatives (1-7), together with five known analogs, were isolated from the lateral roots of Aconitum carmichaelii. Structures of the new compounds were determined by spectroscopic and chemical methods as 4-methyl ( - )-(R)-hydroxyeucomate (1), 4-butyl ( - )-(R)-hydroxyeucomate (2), 4-butyl-1-methyl (+)-(R)-2-O-(4'-hydroxy-3'-methoxybenzoyl)malate (3), 1-butyl-4-methyl (+)-(R)-2-O-(4'-hydroxy-3'-methoxybenzoyl)malate (4), dimethyl (+)-(R)-2-O-(4'-hydroxy-3'-methoxybenzoyl)malate (5), dimethyl (+)-(R)-2-O-(4'-hydroxybenzoyl)malate (6), and methyl ( ± )-3-(4'-hydroxy-3'-methoxyphenyl)-3-sulfopropionate (7), respectively. Compounds 1 and 2 are 2-benzylmalates (eucomate derivatives), 3-6 belong to 2-O-benzoylmalates, and 7 is a rare phenylpropionate containing a sulfonic acid group. The absolute configurations of eucomate derivatives were confirmed by X-ray crystallographic analysis of 4-methyl eucomate (11).